Battery Application Knowledge Basics

Batteries Out of Sight Out of Mind?

By: Andy Wiedeman

Member of the Rocky Mountain A’s of Colorado December 2007.

This research paper is intended to provide basic information on automotive batteries and the charging system for the Model A Ford built between the years 1928 and 1931, however, as much of the information is general in nature it applies to automotive batteries of all types. The Model A Ford was delivered from the factory with a positive grounded 6 volt battery that had an 80 Amp Hour capacity. The Model A battery was the same battery that Ford had used on its Model T from 1919 to 1927. The battery was charged in the vehicle by a two pole 3rd brush type generator which delivered its maximum current about 1200 rpm then tapered off as the speed of the engine increased. At rest the generator was disconnected from the battery by a mechanical relay (the “cutout”) which was activated above about 700 rpm. The Model A did not have a voltage regulator, therefore the battery was prone to overcharging. The charging current was manually adjusted seasonally, or by special needs, by the owner according to his driving conditions. Owners of restored Model A Fords have several options available to them to keep their batteries fresh and increase their battery life. This report discusses options for improving the battery charging system, while keeping the “authentic look” of the Model A generator.

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Footnotes will be found at the end of the paper. Just click the number in [bracket] to read the footnote. The Table of Contents are links to the paragraphs and sections. Click the title to read the information . The Table of Figures are also links to the figures. Click the title to view the figure. Use your browsers “BACK” button to return to the menu.

This report has the following information: Battery types, ratings and what they mean, Quantifies, the original Model A Ford battery capability versus temperature. How to set the original Model A charging system to minimize overcharging How to eliminate battery overcharging and extend Model A battery life How to improve the Model A charging system How to select between using a generator or an alternator How to store and maintain a Model A battery - Winterizing Battery charging techniques, jump starting and testing for state of charge and capacity Provides information on replacement batteries Included is a short history of automotive electrical generation, and the evolution of modern charging systems

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Table of Contents

INTRODUCTION

INTRODUCTION

GENERAL BATTERY INFORMATION

BATTERY BASICS Typical Automotive Battery Design

THE ORIGINAL MODEL A FORD STORAGE BATTERY The Original Model A Ford Battery Design The Original Model A Ford Battery Capacity The Original Model A Ford Recharging Time Versus Temperature

BATTERY LIFE Longer Life with Electrolyte Level Checks Longer Life by Maintenance Charging during Winter Longer Life by Preventing Overcharging

GENERATOR CHARGING RATE SETTINGS TO PREVENT OVERCHARGING The Model A Instruction Book Information on Battery Charging Rate The Ford Motor Company Service Bulletins on Charging Rates Other sources of Information on Generator Charging Rates Summary of Battery Charge Rate Recommendations Driving and Touring Settings for the Restored Model A Semi-Charge Regulation What to do About Overcharging?

GENERATOR OR ALTERNATOR … WHAT ARE MY CHOICES? HOW TO CHOOSE A SOLUTION TO OVERCHARGING

Typical New Restoration Older Existing Restoration New Touring Restoration

BATTERY VOLTAGE State of Charge versus Battery Voltage Check and/or Improve Your Battery Connections Ways to Increase Battery Voltage or Capacity

BATTERY RATINGS Battery Capacity Ratings Battery Reserve Capacity Battery Cranking Ratings

TYPES OF BATTERIES Flooded Electrolyte Types Absorbed Glass Mat Type Gelled Electrolyte Type

AUTOMOTIVE BATTERY OPERATION

CHARGING BATTERIES Battery Charging Voltage Set Points Battery Charging Current Rate Battery Chargers Battery Maintenance Charger System for the Model A

WHAT ABOUT POWER CONVERTERS?

MAINTENANCE AND SAFETY

CARE AND MAINTENANCE BATTERY SAFETY PROCEDURES BATTERY TESTING

State of Charge Tests Battery Capacity Testing

BATTERY CHARGING IN THE VEHICLE Safest Charging Method Quick Charging Method

JUMP STARTING

BATTERY STORAGE

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WINTER STORAGE

APPENDIX 1 … BATTERY AVAILABILITY

APPENDIX 2 … CAPACITY VERSUS DISCHARGE RATE

APPENDIX 3 … VOLTAGE REGULATORS & ALTERNATORS

VOLTAGE REGULATORS Cover Band Mounted Internal Generator Voltage Regulator Cutout Mounted Generator Voltage Regulator Suppliers of Voltage Regulators

ALTERNATORS

APPENDIX 4 … A SHORT HISTORY OF GENERATORS AND REGULATORS

EARLY HISTORY OF ELECTRIC POWER GENERATION FOR AUTOMOBILES THE PROBLEM OF OVERCHARGING AND POWER REGULATION THE ADVENT OF THE 3RD BRUSH GENERATOR AND REGULATION CHARGING CURRENT REGULATION HISTORICAL ELECTRICAL GENERATION AT THE FORD MOTOR COMPANY THE DEVELOPMENT OF THE MODERN CHARGING SYSTEM

Table of Figures

Figure 1 Battery Voltage to Starter vs. Engine Turning Rev/Sec Figure 2 Starter Motor Performance vs Temperature Figure 3 Capacity versus Temperature Figure 4 Electrical System "Garaged" Figure 5 Model A Ammeter Reading during Start Figure 6 Model A Ammeter Reading at Idle Figure 7 Model A Ammeter Reading No Lights Figure 8 Model A Ammeter Reading with Lights On Figure 9 Charge/Discharge Rate vs Ammeter Reading Figure 10 Generator or Alternator what are the Choices? Figure 11 Effect of Bad Connections on Starting Figure 12 Batteries in Series Figure 13 Batteries in Parallel Figure 14 Easy Maintenance Charger Installation Figure 15 RV Battery Storage Operation Figure 16 Safely Charging the Battery in the Vehicle Figure 17 Generator Output vs MPH with various regulation Figure 18 Early Voltage Regulation Operation Figure 19 History of Modern Charging Systems

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Introduction Batteries are one of the most easily overlooked electrical device in the Model A Ford. Its position under the floor board makes it easy to forget. Owners of restored Model A Fords generally have one of three types of battery/generator systems powering their cars. These are 6 Volt positive ground systems with the original Model A Ford generator, a 6 Volt positive ground system with an alternator, or a 12 Volt negative ground system with an alternator. The means of consistently having a fully powered battery available for starting and operating the car in all conditions depends on the system that you have installed. Many Model A owners that tour their cars have changed their electrical system to have 12 Volt operation, to have reliable operation and to avoid the problems with the largely unregulated 6 Volt original Model A system. However, many Model A Ford owners, especially those who show their cars, or those wanting to preserve the original engine compartment look, have kept the original 6 volt Model A Ford system. This paper seeks to inform the Model A Ford owner, about automotive batteries, primarily the common lead-acid flooded electrolyte battery, which is common to most automotive applications. Beyond basic information, the paper also has technical data on charging systems, storage, and maintenance of batteries. While concentrating on the Model A Ford battery and charging system, thecommon sense information presented here, is applicable to all modern lead-acid batteries used in most modern cars and trucks.

General Battery Information Automotive storage batteries typically used in the Model A Ford all work on the same basic principle. Inside the battery casing, they contain lead which are molded into thin plates which are immersed in an acidic electrolyte. This combination has a long history of over 100 years. The plate-acid combination provides usable electricity from stored chemical energy during discharge. The stored chemical energy is replaced by converting direct-current electricity from an outside

source back into chemical energy. The external direct-current power is typically provided by a generator while the car is being driven, but can also be provided by an external battery charger. The discharge cycle is shown here. The electrical flow is from the stored energy in the battery to the various loads such as the lights and the starter. The energy is used to power the components. Connection from the components to ground through the Model A

Frame completes the circuit. The charging electrical flow is opposite that of the discharge electrical current flow and proceeds from either a generator or an alternator which is powered by the automobile engine by turning a shaft connected to electric current producing device. Some sort of current regulating device (usually adjacent to or built into the generator or alternator) is required to prevent battery over charging. The charging cycle is shown in the next figure.

The electrical current flow is from the battery charging device, either a generator or an alternator through a regulation device of some sort and thence to the battery. This electrical current flow is then stored into chemical energy which is used in the discharge cycle to power the loads. To complete the circuit, the battery is connected to the Model A frame, and thence

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to the battery charge device. If the battery is stored in the winter outside the automobile the battery will be maintenance charged by a battery charger with an internal regulation circuit that replaces the automobile generator or alternator and regulation system.

Battery Basics Batteries have been used in automobiles for over 100 years. Early automobile manufacturers experimented with battery and generators with 6 Volt, 12 Volt, 18 Volt and even 24 Volt ratings. By 1928 when the Model A was introduced, many had standardized on 6 Volt systems, however, there were 12 Volt and even 18 Volt systems still in use. [1]

The Model A was not the only car of the time to have a positive ground system. [2]

Manufacturers using the Westinghouse system were positive grounded, while those using the Delco system or the Remy system were negative grounded.

Typical Automotive Battery Design The automotive battery is composed of some number of smaller batteries called cells. These cells with 2 Volts of potential each are connected in series to provide the Battery Voltage Rating. Batteries are sized to provide a certain amount of energy which is stored within the battery case in the form of chemical energy. This stored energy is called “capacity”. The more the capacity, the more electrical energy is available to be discharged into an electrical circuit or device. The largest user of this energy in the Model A Ford is the starting system. Lead-acid automotive type batteries are usually made up of plates of lead and lead oxide, which are submerged into an electrolyte solution of 35% sulfuric acid and 65% water. When a battery is connected to an electrical load a chemical reaction begins that releases electrons, allowing them to flow through conductors to produce electricity. As the battery discharges, the acid of the electrolyte reacts with the materials of the plates, changing their surface to lead sulphate. When the battery is recharged, the chemical reaction is reversed: the lead sulphate reforms into lead oxide and lead. With the plates restored to their original condition, the process may now be repeated. In modern batteries, not available to “Henry’s Battery”, several elements are alloyed with the lead such as calcium, cadmium or strontium to change density, hardness, or porosity of the plates and to make the plates easier to manufacture. There are two basic types of automotive batteries. The starting/shallow cycle type as used in most automobiles, and the deep cycle type used in recreation vehicles and boats. The starting (cranking) or shallow cycle type is designed to deliver quick bursts of energy, usually to start an engine. They usually have a greater plate count in order to have a larger surface area that provides high electric current for short period of time. Once the engine is started, they are usually being continuously recharged. The deep cycle battery type are designed with thicker plates to withstand providing continuous power for long periods of time and a higher number of charge/discharge cycles. While it is possible to use a “deep cycle” battery for a short period of time as an automotive battery, it is not recommended to use this battery type in this manner for a long period of time.

The Original Model A Ford Storage Battery

The original Model A Ford storage battery had evolved from

that of the Model T battery [3]

. It was shipped with all Model A Ford’s. All years of the Model A, had the same battery design. The battery that was shipped with the Model A Ford in the years 1928 to 1931 was a flooded electrolyte 6 volt battery, with an Amp-Hour capacity rating of 80 AH. The

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battery was manufactured by the Ford Motor company itself, to specifically meet the requirements of the Ford car. Ford was the only automobile manufacturer to

make its own battery. [4]

The original battery as shown in the adjacent picture from page 514 of the Model A Ford Service Bulletins, contained 13 lead plates and a hard rubber casing. Ford claimed that the original battery had a “starting capacity” of 98 Amps. It is not clear that this value corresponds to any of the current definitions of various battery ratings. Research shows that when the temperature is about 80 degrees F. the battery will provide about 98 Amps of cranking current [5]

. Various Ford service bulletins showed a charging rate of 6 to 14 Amps depending on the season and driving habits. The physical size of the original battery is 6 ¾ x 8 7/8 x 9 ¼ high. Original type batteries with the Ford script are available from various Model A parts mail order dealers if you want to have a show quality battery. See Appendix 1 for various options available. Ford recommended checking the electrolyte in the battery every two weeks, to see that it is at the proper level at the bottom of the filling tube. It was recommended that distilled water that was storedin clean glass, rubber, lead, or china vessels. Ford in the Model A instruction book, recommends that in cold weather, water should be added only just before the car is started, to prevent freezing. Ford also recommended that the battery be kept clean, and wiping the battery with a rag moistened with ammonia to counteract the effect of any water/electrolyte solution on the outside of the battery. Additionally, they recommended a coating of vasoline on the terminals to counteract corrosion.

The Original Model A Ford Battery Design The basic function of the Model A Ford battery is to start the car. It is this starter motor power requirement which sizes the battery system for the Model A. Unfortunately, there are several opposing factors which combine to make it difficult for the Model A. Firstly, the voltage of the Model A Ford electrical system was designed around the most common voltage in the low cost automotive industry of the time, 6 volts. There were other voltage systems including 12 volt systems prior to the Model A, such as the Dodge Brothers cars built from 1914 to 1925, but most manufacturers designed around the 6 volt “standard”. Henry Ford’s Model T was a 6 volt system. The eventual universal 12 volt standard of today was yet to be established. Secondly, the lower voltage starter motors of that day were less efficient than the 12 volt starters of today. More importantly, thirdly due to engine friction, poorer combustion, and oil viscosity, a Model A engine requires more power to start as the temperature goes down. Les Andrews, in his Model A Ford

Mechanics Handbook [6]

, shows that it takes nearly double the power to crank a Model A engine at zero degrees Farenheit than it does at 80 degrees. Unfortunately the starting power capacity available from the battery goes down by 60 percent over the same temperature range. Finally, the Model A was shipped with the lowest capacity battery of all makes in those years. Furthermore, the conditions of the connections between the battery and the starter, and the battery to the frame ground, will affect the ability of the car to start, especially in cold weather. The remainder of this discussion assumes that the connections are good and do not cause a reduction in capability to start. We can compare the Model A Ford battery to those used in other makes of automobiles of the time. In 1928 the capacities ranged from 80 Amp-Hr used in the Model A to 192 Amp-Hr. used in the Stearns Knight. The average was about 130 Amp-Hr with the larger capacities in the more expensive cars. Only Overland and the Pontiac 6 used a compariable 80 AH battery. Other low cost cars, used somewhat higher Amp Hour batteries such as; Chevrolet 90 AH, Dodge 100 AH, Essex 105 AH, Nash 110 AH, Plymouth 90 AH, and Studebaker at 100 AH. To understand the operation of the starter motor – battery relationship we must reverse engineer the Model A starting system. The original design specifications are sparse and do not give a complete story. Fortunately, we have some test details and some estimates, as well as some Ford

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specifications to work from. In this paper, what is important is the relationship of starting motor performance versus temperature. After developing these values we can then apply these requirements to the battery design to see the capacity to start the Model A under unfavorable conditions and/or under multiple attempts to start the car.

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Here is what we have to work with.

1) Tests of the Starter Motor [7]

have determined the relationship between starter motor torque, voltage, amperes, and starter revolutions per minute.

2) The Starter Motor to Engine Flywheel gear ratio = 11.2 : 1 [8]

3) Les Andrews table of Temperature vs. Starter Motor Power 1 These values can then be related to the following chart. The following discussion is limited to the starting motor performance for a Model A Ford manufactured during the years 1928 to 1931 using an original stock 6 Volt battery with positive ground.

Figure 1 Battery Voltage to Starter vs. Engine Turning Rev/Sec

The open circuit voltage of the Model A battery is 6.3 Volts. As long as the current draw for any other device is small, this is the voltage that will be initially applied to the starter if the battery is fully charged. When the starter motor switch is depressed this voltage will instantly drop according to the current draw, and is applied to the starter motor and current will begin to flow through the starter and thence to ground. The motor will turn its pinion gear at an RPM that is determined by the load on the gear and the battery voltage. The load on the gear is applied via a large gear on the flywheel. The ratio of the flywheel gear to the starter pinion gear is 11.2 :1 Depending on the temperature, friction, oil viscosity, and the condition of the battery at the time of starting, the engine will begin to turn if its starter motor torque can overcome the value of the stalled power requirement. Testing has shown that the starter motor will stall (be locked) at a power of about 3 Volts x 550 Amps = 1650 Watts and is equivalent to about 15 ft-lbs of torque when the pinion has Zero Revolutions per Second (RPS) . Likewise, if the starter motor has no load (engine disconnected) the starter motor free running speed is 4000 RPM at 6 Volts and 50 Amps (300 Watts) or an equivalent engine Revolutions per Second of about 6 RPS. Typical Model A starting revolutions are between these two values.

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The starting current of the Model A with a 6 Volt Battery is high, nominally 100 to 200 Amps. This high current demand causes the Voltage of the battery to sink from its open circuit voltage of 6.3 Volts, the higher the current demand the lower the voltage that will be applied to the starter. Higher currents and therefore lower voltage is caused by the Model A having an increased friction load. This relationship is shown in the above chart. Typically, at high temperatures and low friction, with a fully charged battery, the current demand is about 100 Amps which drops the battery voltage to about 5.9 Volts. At this value the engine will turn at about 4 revolutions per second. As the temperature goes down, and friction goes up due to oil viscosity and friction within the engine, the starter motor torque requirement increases causing the starter motor to demand more current. Increased current, can cause currents in the starter motor windings to be up to 275 Amps or higher. As the demand for current goes up the battery can only supply this current at a loss in voltage and subsequent lower revolutions per second. For example; if the current demand is increased to 175 Amps, the battery voltage will sink to about 5.3 Volts and the engine revolutions per second will drop from 4 RPS to 2 RPS. This effect is repeated until the Model A engine is turned with great

difficulty. This point is typically reached when the battery voltage is about 4.5 Volts [9]

and the starter current is about 275 Amps. The nominal recommended battery voltage for starting the Model A is determined from the chart as between 5.9 and 5.3 Volts which produces 100 to 175 Amps of current. These values will turn the Model A Engine (in good working order) at between 2 and 4 revolutions per second. Below 5.3 Volts and down to 4.5 Volts it is uncertain whether the Model A will start. While it is possible that the engine can catch a spark and power up between 1 and 2 RPS it is not reliable. Below 4.5 Volts it is unlikely that the Model A will start. Now we turn to the consideration of starter motor performance versus temperature. The reference to

starter motor requirements versus temperature are from Les Andrews [10]

. This chart shows the “starting power” required by the engine (starter motor torque) versus temperature. These values over the range from 80 to -20 degrees are in close agreement with test observations. The experimental data shows that as the temperature approaches -20 the linear relationship of temperature versus torque (and therefore the starter current) required to spin the pinion begins to become non-linear and increases exponentially to finally locking up at about -40 deg F. Figure 2 Starter Motor Performance vs Temperature shows these relationships. Bench tests on the starter motor, yielded the starter motor current versus engine RPS during the starting cycle. However, these tests did not include temperature effects and oil viscosity or the ability of the battery capacity to supply the needed power. The Ford engineers of the time understood the need to reduce oil viscosity in the winter to allow the Model A to be started after standing in below zero farenheit temperatures for some time. Therefore, they recommended using 20 weight oil in the winter and 40 weight oil in the summer. It is unknown which oil has been used to determine the effect on starter motor torque due to lower temperatures in the Les Andrews chart of starter motor power versus temperature. However, we can speculate that using a modern multigrade oil such as 10W-40 in a Model A will inprove the performance somewhat in the lower temperature range, perhaps even allowing the Model A to be more reliably started in temperatures approaching -20 degrees.

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Figure 2 Starter Motor Performance vs Temperature

The Figure 2 Starter Motor Performance vs Temperature also shows that the Model A is reliably started between 100 and 32 degrees Farenheit, but begins to show difficulties below 0 degrees F. The engine revolutions per second generated by the starter are determined primarially by the battery voltage as shown in Figure 1 Battery Voltage to Starter vs. Engine Turning Rev/Sec. The Model A’s battery condition and state of charge at the time of attempting to start the car, will determine the battery voltage that can be applied to the starter, and therefore the revolutions per second of the

engine. Assuming that the battery is “fresh” [11]

, fully charged and able to deliver at least about 5 volts, the engine should reliably start between the temperatures of 100 degrees and to below 0 degrees F. However, if the battery capacity is reduced because of age, lack of complete recharging, or have some of the internal lead plates defective, or if the engine friction is high, and the oil is heavy and viscous, the car may only reliably start between 100 and about 32 degrees F. Therefore, we divide the curve depicting Engine revolutions versus temperature into a red zone, a blue zone, and a black zone. The red zone means reliable starting under most conditions, blue under favorable conditions, and black starting only under rare conditions. These observations are made from the

available data. [12]

Now that we know the starter motor performance versus temperature, we can estimate the capability of the original Model A Ford 6 volt battery with its 80 Amp-Hour capacity to start the car at various temperatures

The Original Model A Ford Battery Capacity The Ford Motor company sized its 6 volt battery as an 80 AH battery as shown in its literature of the time. As discussed before, the Amp Hour capacity of the Model A battery was the lowest of the

manufacturers of the time. Data by Jim Schild [13]

shows that the Ford Motor company used near traditional means of estimating Amp Hour rating for its batteries. Traditionally the battery Amp-Hour rating is given by the following equation:

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Rating Amperes = Rated Capacity /20

For the Original Ford Battery would be 80/20 = 4 Amperes. However, there is no evidence that the Ford engineers used this value. Evidence for this provided in Schild’s book where he states that the “lighting capacity was 5 Amps for seventeen hours. This translates to a capacity of 85 Amp-Hours, pretty close to the original 80 AH Ford battery. It is widely known, both then and now, that heavy current draws or rapid discharging reduces capacity of the battery to deliver energy. For example; if we assume that an 80 AMP-Hour batttery (rated at 4 Amps) is being drained with a 100 AMP load that the battery capacity would allow cranking at this level for 0.8 hours we would be in error. A German scientist named W. Peukert

experimented with batteries in 1897, and established Peukert's [14]

Law, which expresses the capacity of a battery in terms of the rate at which it is discharged. As the rate increases, the battery's capacity to deliver decreases, although its actual capacity tends to remain fairly constant. In other words, as the temperature decreases the battery ampere draw increases, linearly at first, and non-linearly as the temperature drops below 0 deg F. As this current draw increases, the capacity of the battery to supply this current decreases. Peukert’s law (described in Appendix 2) can be expressed so that we can calculate the time that a rate of Amps of current can be extracted from a battery. Peukert’s work has been used for many decades as the means of determining battery capacity during high current discharge. Other researchers have improved on the means of using Peukert’s work and have determined an equation which utilizes commonly advertised capacity ratings for various batteries. The following discussion is limited to lead-acid batteries such as used in the Model A Ford. Peukert determined that there is a constant which can be used to derate the capacity of a battery as the discharge rate increases. This constant cannot be used across different battery chemistries. It must be used to predict performance within the group of batteries to which it applies.

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Having said all that, the Peukert equation for discharge time can be stated as:

where:

H is the hour rating that the battery is specified against C is the rated capacity at that discharge rate. I is the discharge current, expressed in A. k is the Peukert constant and t is the time of discharge, expressed in hours

The battery capacity for starting the Model A has been stated by Jim Schild as “Starter Capacity

required is 98 AMPS for 20 minutes” [15]

. To determine if Schild is correct, since he does not state where he got this information, we can check the Ford Motor company specifications. Ford

published [16]

that the Model A battery is an advertized 80 AH battery. At the specified low current draw of 5 Amps this yields 16 hours of capacity. Using Peukert’s equation, with a Peukert constant

of 1.3 for a “fresh” battery [17]

and the advertized values;

16 16 t = --------- = -------- = .334 hours = 20.01 Minutes (98 x 16/80)1.3 47.85 where:

H is 16 hours (80 amp-hours divided by 5 amps) where 5 amps is the low discharge rate. C is 80 Amp-Hours I is 98 Amps k is the Peukert constant = 1.3 for “fresh” lead-acid batteries t is the time of discharge and t is expressed in hours at a constant 98 Amp discharge rate

Therefore, Schild is quite correct in that the original Ford battery can deliver 98 Amps of cranking power for 20 minutes. Now we can extrapolate this to other values of current discharge rates at various temperatures. The Figure 3 Capacity versus Temperature describes the capacity of a Model A battery to deliver therequired starting power to the Model A starter versus the temperature of the system at the time of initiating starting. The conditions of the validity of this chart are; a “fresh battery” (not one that is 4 years old), a fully charged battery, a battery with at least the 80 AH rating of the original Ford battery. At temperatures of about 70 to 80 degrees Farenheit, the required starter motor curren is about 100 Amps, this heavy draw causes the battery to have a capacity reduced to 40% of its rated capacity or about 32 Amp Hours. It can deliver the current for about 16 minutes. The chart shows that at a low temperature of -20 deg F, the extra current draw, reduces the advertized capacity to about 25% of the original, and can only deliver about 3 minutes of cranking power to start the Model A . This does not mean that the car will actually start, that depends on the volitility of the gasoline, the condition of the engine and the type and condition of ignition system. Older batteries, and those batteries that have been poorly maintained, and have high degrees of sulphation (we will discuss this

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later on), will deliver much less capacity than shown in the chart. Since it is unlikely, that a restored Model A owner, will be using the vehicle in such adverse condtions, the 80 Amp Hour capacity is adequate for the hobby car. In 1928 to 1931, a higher capacity would certainly have been welcome.

Figure 3 Capacity versus Temperature

The Original Model A Ford Recharging Time Versus Temperature The original Model A Ford battery recharging system is equipped with a generator and a sort of psudo-regulating system called “the third brush”. The Model A Ford is also equipped with a “cutout” The purpose of the cutout is to prevent the battery from discharging back through the generator to ground if the car is stopped or moving at a slow speed. The cutout does not perform any voltage or current regulation at speeds above 10 mph. The cutout will close and the generator will begin to supply current to the electrical system at about 700 RPM or a car speed of about 10 mph. This varies of course depending on the cutout and the 3rd brush settings. The generator will act as an electric motor if it is connected directly to the battery, with the engine running the engine drives the generator pully enough to provide the current necessary to operate the various electrical circuits and charge the battery. When the Model A gets up to 9 or 10 mph the generator produces enough current to cause the magnetic field in the relay of the cut-out switch to activate and “close” the contacts, connecting the generator to the battery, allowing the generator to provide power to charge the battery. When the Model A speed drops to about 7 to 8 mph the current flow to the cutout winding drops below the value to keep the relay closed and the cutout “opens” and disconnects the generator from the battery. Typically, the generator is adjusted to produce some number of Amperes of

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charging current with the lights and other current draws are turned off. The amount of Amperes was manually adjusted by the owner, according to his driving habits and the season of the year. The output of the generator is adjusted by moving the third brush of the generator. During daylight operation the battery is charged with about 9 to 10 Amperes which is reduced at night by the lights which draw about 6 Amperes. Thus at night the battery charge is reduced to about 4 Amperes. As opposed to modern voltage regulated charging systems such as found in older generator charging systems, and modern alternators, the stock Model A Ford will not charge the battery when idling. Typically, the idle speed of a Model A is below 700 RPM, therefore, the generator is not providing enough current to close the cutout switch. Thus, to charge the battery we must drive the car at some speed above 10 mph for a long enough time to replace the amp-hours of capacity that were removed from the battery during the starting cycle. To understand this, we resort to an example or two. Example 1: A Model A with a “fresh” battery is started at 60 degrees Farenheit. From our previous chart we have shown the starter motor to requireabout 125 Amperes to turn the engine at 2 ½ revolutions per second. From experience this takes up to about 15 seconds to start the engine. We can calculate the Amp-Hours extracted from the battery from the equation: AH (removed) = Starting Current

(amperes) x Time Starting

(in hours) = 125 x 15 seconds = 0.52 AH

To replace this capacity lost due to starting we must drive the car with the generator charging at 10 Amps for the time shown below: AH (replaced) = Charging Current(amperes) x Time Driving(in hours) Solving this for the time required yields: AH (removed) 0.52 AH Time Driving = ---------------- = ------------ = .052 hours = 3.1 Minutes Charging Current(Amperes) 10 A Not a very long time. But consider the next example: Example 2: A Model A with an older battery which has had some neglect is started at 0 degrees Farenheit. From our previous chart we have shown the starter motor to require about 250 Amperes to turn the engine at about 1 ¼ revolutions per second. At this temperature it may take up to a minute of cranking (4 attempts at 15 seconds each). As before, we can calculate the Amp-Hours extracted from the battery. AH (removed) = 250 A x 60 seconds = 250 x .0167 hr = 4.3 AH The driving time to replace this capacity is 4.3 AH Time Driving = ---------- = .43 hours = 26 Minutes 10 A If this is at night the time necessary is increased since the battery is only charged at about 4 Amps requiring about 1 hour of driving time to replace the capacity. Consider the 1931 pastor of a church in the midwest during the winter at 0 degrees F. He goes out to his Model A with a fully charged battery that has about 22 AH of equivalent starting capacity and

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starts the engine in the evening with the temperature at 0 degrees and drives 10 minutes to visit one of his congregation. He removed 4.3 AH from the battery and replaced only 1.7 AH. Therefore his battery is now down to about 20 AH. He stays for a couple of hours and the engine cools down to ambient. He then starts the car and drives 5 minutes with the lights on to the church to attend a committee meeting. He is now down to about 18 AH. After 3 hours, the pastor again starts the Model A and drives home after dark with the lights on, and since it is snowing and icy he drives slow at less than 10 mph, and parks the car. The next morning the temperature has dropped to -10 and the pastor is stuck with a car which won’t start! Lucky for us, the modern day owners of our pride and joy restored Model A’s, we pamper and baby the 75 year olds and wouldn’t think of taking them out in 0 degree or below weather. Therefore we will probably never be in the situation of the old time pastor. But, think of those times, it was not easy to be a Model A owner then. The owners of these cars in the olden days had to think of the conditions that they were going to be in, and travel accordingly. I remember that my father, who owned a 1935 Ford during World War II , would agonize over attempting to travel from Long Beach to Pasadena in southern California for hours if the temperature was below 32 degrees. This distance was all of 25 miles, but for him it was the equivalent of 1000 miles for us today.

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Battery Life Battery Life depends on how they are used and maintained, temperatures, and even storage periods. Deep discharges, rapid charging, extreme temperatures, and continuous use all shorten a battery’s life. A poorly maintained battery, that is consistently overcharged by the Model A generator, and stored for several months without a maintenance charger may only have a life of 2 years. On the other hand a properly maintained battery, that has had limited overcharging, or one with a voltage regulator that prevents overcharging, and has been stored with a maintenance charger may last up to 5 years. While batteries are not the most expensive devices on a Model A, it is comforting to know that while you are on the tour, in the middle of nowhere, your Model A is going to start. The ability to find an 80 AH 6 Volt battery in Podunkville Kansas, may be difficult. The main four problems of battery life are, lack of electrolyte due to evaporation caused by the charging process, storage at a low state of charge, storage at low temperatures with the battery at a low charge level, and overcharging by the Model A generator. The ability to discharge and recharge flooded electrolyte lead-acid batteries is also limited by battery life, as the battery ages the recharge capability decreases. We will now discuss the main problems that cut short the life of a battery.

Longer Life with Electrolyte Level Checks For the Model A Ford the easy one to keep under control is prevention of the lack of electrolyte. However, we too often forget about the battery, since it is hidden away under the floor boards. Too low an electrolyte level in the battery has two effects. Firstly, the concentration of acid to water is increased. This increase in electrolyte acid concentration chars and disintegrates the separators between the lead plates. In addition, the plates themselves become partially exposed to air, stopping chemical action from taking place, and limits recharge ability, and reduces capacity. It is a relatively simple maintenance procedure to remove the battery inspection plate attached to the floor board, directly under the steering wheel, remove the battery caps (if you are not using a “maintenance free” battery) and check the electrolyte level in the cells. The electrolyte should be level with the bottom of the filler tube. This process has not changed since the Model A Ford was produced. Ford, in its

instruction book [18]

, says that the owner should;

“Every two weeks check the electrolyte in the battery to see that it is at a proper level. The solution (Electrolyte) should be maintained at a level with the bottom of the filling tube. If below this point, add distilled water until the electrolyte reaches the proper level”

Longer Life by Maintenance Charging during Winter Even if there is no load on a typical automotive battery, the battery will lose a small amount of charge as time goes on. Just sitting around, the battery will “self discharge”. As the battery discharges lead sulphate accumulates on the surface of the plates and reduces capacity. When recharged, most but not all, of the lead sulphate returns to the electrolyte. However, the remaining small amount accumulates and reduces capacity. Therefore, a battery as soon as the electrolyte is added, begins a slow automatic “wearout mechanism” and will deteriorate over time, even if it is not used, or even if it is trickle charged. If a battery is left in a low state of charge for a prolonged period of time, the plates become heavily sulphated and may permanently lose the capability of being recharged. Storage of the Model A with a low state of charge can cause the battery to fail in cold weather. Leaving a battery in the car over the winter without maintenance charging will cause the battery to self-discharge and have a low state of charge. When batteries are left in a low state of charge they

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quickly become sulphated and may even permanently lose the ability to be recharged. While, at a high state of charge, a fully charged battery is quite resistant to freezing and can survive temperatures well below zero. However, when discharged, they have a much higher ratio of water to acid level and can freeze at just a few degrees below the 32 degree freezing point of water. Therefore, it is important for these two reasons to keep the battery on a maintenance charger during the winter when the car is not being driven. Freezing of the battery water-acid mixture can crack the case and destroy the battery.

Longer Life by Preventing Overcharging The more difficult of these enemies of battery life to prevent is over charging. The charging system of the Model A does not have a voltage regulator to reduce the amount of charge current put into the battery during driving after the battery is charged. Overcharging causes the positive lead plates to flake and float to the bottom of the case and form a “floor” of a thick mud like substance. This substance is conductive and if it reaches the level of the plates will short out one or more of the battery cells, causing the battery to fail due to low voltage supply. The battery case is designed to allow some amount of this flaking. The Model A Ford the life of the battery is directly related to overcharging. Since the stock generator charging system is regulated for current only and puts out a constant current, determined by the position of the 3rd brush, to the battery regardless of the state of charge, it is easy to see that the battery can be overcharged. Ford introduced voltage regulation to provide overcharge protection in 1935. For example: A Model A Ford with a fully charged 6 Volt battery is started at about 60 degrees Farenheit. The amount of energy taken from the 80 AH capacity battery is about 0.52 Amp-Hours which is replaced by the generator after only about 3 minutes of driving. After this, the generator is supplying excess charge which is not needed. Overcharging of the Model A battery due to constant current operation of the generator was a continuing problem for the Ford Motor company and the Model A owners of the time. This problem existed for not only the Model A owners of the time, but other manufacturers as well. Ford issued seven (7) service bulletins over a three year period advising dealers and mechanics to address the issue of overcharging.

Generator Charging Rate Settings to Prevent Overcharging

With the stock Model A Ford charging system, using the 3rd brush generator, it is probably not possible to prevent overcharging. Various charge rate settings can be trialed but non will fit all driving conditions that you will face. The “right” generator charging rate for a stock Model A Ford is a matter of debate. The Ford Motor Company during the years of manufacture, issued a number of Service Bulletins which have shown ever lowering generator charge rate settings. Over the years, restoration specialists have

recommended other settings. Some specialists recommend setting the 3rd brush for 10 Amps [19]

, others much lower . However, as shown below, this rate is too high for summer time and touring of the stock Model A Ford. Jim Schild recommends a general setting of 6 Amps and reducing this to 2

to 4 amps when on a tour [20]

. To learn more about the proper setting, and to learn how to prevent overcharging read the following.

The Model A Instruction Book Information on Battery Charging Rate During the years of manufacturing the Model A, Ford told owners that the generator charging rate

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should be adjusted seasonally [21]

. Ford recommended the following;

“During winter months where low temperatures prevail the charging rate should be adjusted to 10 Amperes; in the summer this rate should be cut down to 6 Amperes.

Ford went on to also say that owners should increase or decrease the charging rate to individual requirements and that:

“An owner who takes long daylight trips could cut down the charging rate even less. On the other hand, the owner who makes frequent stops, should increase the normal rate if his battery runs down.”

The Ford Motor Company Service Bulletins on Charging Rates Beginning in June 1928 Ford began to notify its dealerships, through the Service Bulletins, of the problem of overcharging the battery. The following information has been gleaned from a book

which compiles all of the Model A Service Bulletins. [22]

The Ford Service Bulletin for January 1928 [23]

said something different than the instruction book. The service bulletin stops short of recommending an average charging rate of 12 Amperes.

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The service bulletin says;

During winter months the charging rate should be adjusted to 14 Amperes; in the summer this rate should be cut down to 10 Amperes. The rate can of course, be increased or decreased to meet individual requirements. For example, the owner who takes long daylight trips should cut down the charging rate to 8 Amperes to prevent battery overcharging. On the other hand, the owner who makes numerous stops, should increase the normal rate if his battery runs down.

The Ford Service Bulletins for June 1928 and May 1929 told the dealer mechanics that “with the arrival of warm weather” the charging rate of the generator should be changed and provided information on how to adjust the charging rate. Apparently Ford considered that its original rates of 14 Amps winter, and 10 Amps summer was too high, and suggested a 40% lower rate of 6 Amps. The rate recommended was;

“For average driving a charging rate of 6 amperes or slightly less is sufficient and prevents the possibility of overcharging the battery. This rate can, of course, be increased or decreased to meet individual requirements. For example, the owner who takes long daylight trips can operate with a comparatively low rate. On the other hand, the owner who makes numerous stops can increase the normal charging rate if the battery shows indications of running down.”

Another Service Bulletin for December 1928 tells the Ford dealers to inspect cars carefully for battery charging rates, and again reduced the charging rate;

Generator Charging Rates: Should be adjusted to suit individual requirements. For average driving during cold weather, a charging rate of 10 Amperes at 1500 RPM will prove satisfactory.

Yet another Service Bulletin for May 1929 tells the Ford dealers that:

For average driving during the summer months a charging rate of 6 Amperes is sufficient. This rate can of course be increased or decreased to meet individual requirements. For example the owner who takes long daylight trips could cut the charging rate down even less. On the other hand the owner who makes numerous stops should increase the normal rate if his battery becomes weak.

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By mid 1929 Ford was even more worried about customer satisfaction and advised the dealer mechanics to check with the owners and adjust the charging rates. The May 1929 Service Bulletin adds an admonition in bold letters that the dealers should;

“Instruct mechanics to check owners’ cars and adjust the charging rate to suit conditions under which the car is operated. This is important.”

The October 1929 Service Bulletin shows that Ford has become sensitive to owners having trouble with the “affect of cold weather on the electrolyte in the battery, and the failure of mechanics to correctly adjust the generator charging rate to meet the conditions under which the cars are operating.” The October 1929 Service Bulletin admits that “Hard Starting Resulting in Run Down Batteries” is a possibility at Zero temperatures. The bulletin states;

At Zero temperatures the starting ability of a battery is reduced to one-half its normal capacity and its internal resistance proportionally increased. In other words, a battery that will crank the engine for five minutes at normal temperatures, will only crank it 2 ½ minutes at zero temperatures, and only about half as fast. In addition, the amount of daylight driving is considerably reduced. Also due to congealed oil, the engine is stiff and requires considerably more power to turn it over. These conditions often result in a battery becoming partially or fully discharged.

When trouble of this kind is experienced the remedy is to increase the generator charging rate by 3 to 5 amperes.

This bulletin goes on to say that the cause of bulbs burning out can be caused by the generator charging rate being set too high. The bulletin also claims that if all of the connections to the electrical system are clean and tight the remedy is to “cut down the generator charging rate approximately 2 to 4 amperes” However, the bulletin says that battery charge status should be monitored and adjusted again accordingly. The Ford Service Bulletin for April 1930 says that;

“Adjust the charging rate for summer driving 6 to 8 amperes at 25 miles per hour should be sufficient.”

The October 1930 Service Bulletin had a large article on the generator charging rate. It started out with a statement that the Ford Dealers should “Keep the customer satisfied, make sure that the generator charging rate is NOT too high or too low.” The bulletin says that Ford Dealers should

“Check generator charging rate for cold weather operation on all cars coming into your shop”

and that; “For average driving during cold weather, a charging rate of 10 to 12 amps is sufficient.

This bulletin also gave the now familiar song about the rate can be adjusted up or down for the customers driving conditions. The Ford Company said in this bulletin that;

“it takes 20 minutes running, with the generator set at average charging rate to replace in the battery the current taken out by one minute’s use of the starting motor. “

The bulletin fails to say what the “average charging rate” is. The bulletin also repeats the hard

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starting information that was presented in the October of 1929 Service Bulletin on cranking time.

Other sources of Information on Generator Charging Rates Jim Schild in his book on restoration of the Model A claims that the generator is capable of putting

out as much as 22 Amps, but it is recommended [24]

that it be set at 6 Amps for normal driving situations. He claims that “for extended daytime trips, a lower rate of 2 to 3 Amps is desirable to prevent damage to the generator and battery. The earliest non-Ford Service Bulletin discussion on the issue of overcharging the battery is found in

a book by Victor Page [25]

published in 1931. He writes that “During the Winter months, the charging rate should be increased from the 10 Amp “Summer Average” to 14 Amps. He also writes that the rate should be increased or decreased “to meet individual requirements”, and gives an example which is probably accurate for the type touring and driving of our Model A’s. “The owner who takes long daylight trips should cut down the charging rate to 8 Amperes to prevent battery overcharging.” Page concludes that for “average conditions, however, a charging rate of twelve (12)

amperes [26]

is the most suitable”. Page’s information is consistent with the earliest Ford Service bulletins, but is not up to date with the latter ones that recommend a lower charging rate. More recently, Les Andrews in his book on the Model A says to adjust the generator brush for a 10 Amp

charging rate.[27]

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Summary of Battery Charge Rate Recommendations We can now make a table of the various suggestions on how to set the generator charging rate versus driving conditions and seasons.

From the Ford Service Bulletins issued, it appears that Ford always recommended adjusting the charging rate seasonally, and continued to revise its recommended charging rate downward. Final settings recommended by Ford seem to be those presented in the 1931 Instruction book, since there are no service bulletins on the subject in 1931. It appears that Ford finally settled on an average setting of 6 Amps for the summer season and 10 Amps for the winter. These values were, however, to be adjusted up or down to meet individual customer requirements. Victor Page seems to make his recommendation stemming from the original Ford settings of 10 to 14 Amps in early 1928 and in general these settings are too high. Jim Schild recommends a charge rate setting on the low end with an average setting of 6 Amps, with a reduction to 2 to 3 amps for long tours. This would conform to Ford’s recommendation for summer driving. Whilst, Schild does not state information about winter driving, it is perhaps since he assumes that the restored vehicle is going to be used in warm weather only. Les Andrews recommended setting of 10 Amperes seems too high for summer driving and may lead to an overcharged battery.

Driving and Touring Settings for the Restored Model A Since there seems to be a wealth of values postulated as where to set the generator charging rate, where does this leave us? It appears that for our typical restored Model A driving conditions, especially in the summer when driving around town, we should adjust the generator, if you don’t have a voltage regulator, charging rate to somewhere in the vicinity of 5 to 8 Amperes. If we take a long tour (anything over 100 miles) we should cut the charging rate down to about 4 to 6

Where to Set the Model A Ford Generator Charging Rate (Amps)?

Recommender Overall Average

Summer Winter Average Long Day

Trips Average Long Day

Trips Ford Service Bulletin Jan 1928

Adjust Seasonally 10 8 14 Less than 10

Ford Service Bulletin June 1928

Adjust Seasonally 6 Less than 6

Ford Service Bulletin Dec 1928

Adjust Seasonally 10

Ford Service Bulletin May 1929

Adjust Seasonally 6 Less than 6

Ford Service Bulletin Oct 1929

Adjust Seasonally 9 to 11

Ford Service Bulletin Apr 1930


Ford Service Bulletin Oct 1930


Ford Instruction Book 1931 Adjust Seasonally 6 Less than 6 10 Less than 10 Victor Page’s Book in 1931 12 10 8 14 Les Andrews Handbook 2000

10

Les Andrews Diagnostic 2000

10 8

Jim Schild Shop Manual 6 2 to 3

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Amperes. One must be careful in these lower settings, because if there is much night driving with the lights on, it is possible, since the headlights draw about 5 Amperes or more, to put the battery into a discharge condition all the time while driving at night. During the winter, if we start the Model A in temperatures about 32 degrees or less we should set the charging rate up to about 8 to 10 Amperes.

Semi-Charge Regulation If we take a longer trip with the generator charging rate set to the high side say 10 Amps, there is a trick we can play. The lights can be used as a generator charge reduction trick. This trick was commonly known by the owners of both the Model T and the Model A during the 20s and 30s. The ammeter is used to gauge the charging rate to the generator. Since the generator both supplies power to run the electric lights and to supply the battery recharge. The current demanded by the lights will automatically reduce the generator charging current to the battery. The Ammeter a means of monitoring the charge rate, is connected as shown in the figures below.

Figure 4 Electrical System "Garaged"

The figure shows the electrical system with the Model A not running and with the lights and other devices turned off. The ammeter is positioned between the output of the cutout and the battery, therefore it will always indicate the total flow of the current to or from the battery which will be dependent on various conditions. It will not indicate the current flow to the starter. When “garaged”with the motor not running, and all lights etc. turned off. The ammeter should read zero (0 Amps). When starting the Model A the current flow will be from the Battery to the Starter Motor as shown Figure 5 Model A Ammeter Reading during Start. Since only a small amount of current is flowing to the ignition circuit, the ammeter will be reading near zero or slightly negative.

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Figure 5 Model A Ammeter Reading during Start

The generator, while turning slowly, is not generating enough current to close the cutout relay. The battery will discharge a large amount of energy to the starter. In warm weather the amount of Amp-Hours withdrawn from the battery is typically about 5 seconds of cranking at about 100 Amperes or about 0.3 Amp Hours. During cold weather or in the morning this can be on the order of 15 seconds at 175 Amperes or about 0.7 Amp-Hours. This energy will need to be replaced by the generator after the car is running. At Idle or below about 700 RPM (about 10 MPH) the stock generator cutout will not close and the current flow as shown below will be out of the battery to the ignition system. If you have replaced the stock relay cutout with a diode type any current available from the generator will flow through the ammeter.

Figure 6 Model A Ammeter Reading at Idle

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At idle or, during driving the Model A, at speeds below about 10 MPH the battery will discharge,

since the generator is not connected. [28]

If the car is driven at this speed or less with the lights on, an additional discharge of about 5 Amps times the time at speeds of 10 MPH or less. This additional discharge will add to the amount of Amp-Hours extracted from the battery. Figure 7 Model A Ammeter Reading No Lights shows the current flow above about 10 MPH. After the cutout closes the generator develops an output current which depends on the setting of the 3rd brush. This current flows out of the generator at the output of the cutout and divides into that required of the electrical circuits turned on in the Model A and battery charging. During daylight this is the ignition circuit and any other accessories or the brake light. The remainder of the current flows through the ammeter and thence to the battery providing charging current. With the lights on the current to the electrical circuits increases due to the lighting load and decreases to the ammeter and the battery. One can see this effect simply by starting the car, and observing the ammeter. With the Model A running at 1200 to 1500 RPM observe the reading of the ammeter, it will be near the setting of the 3rd brush of the generator. If set at the example 10 Amps the ammeter should read about 10 Amps. Now step on the brake. The additional current to the brake lights will reduce the

charging current from 10 Amps to approximately 5 to 8 amperes [29]

.

Figure 7 Model A Ammeter Reading No Lights

Turning the headlights on will cause a large current to flow to them, about 5 Amps. This current reduces the current flow to charge the battery as shown Figure 8 Model A Ammeter Reading with Lights On.

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Figure 8 Model A Ammeter Reading with Lights On

In the 1930’s and 1940’s this trick was used by drivers to keep from overcharging the battery. During the daylight, the driver would start the car and drive for 10 to 15 minutes to replace the charge in the battery due to starting. Then the driver would turn on the headlights to reduce the charge to the battery thus helping to not over charge the battery. In the above example the setting of the generator 3rd brush is to give a 10 Amp generator output. Turning on the headlights causes them to draw about 5 Amperes. The 10 Amps divided current remaining from the generator is about 5 Amperes and shows on the Ammeter as a 5 Amp reading. If the Model A owner had adjusted his generator to the 6 Amp output as recommended by Ford in one of its service bulletins, the additional current draw of the headlights would reduce the battery charge current to, theoretically, 1 Amp. On the other hand if you have more current draw for the

lights [30]

you may be driving with the ammeter showing discharge. This will not cause great difficulty since even if you drive with a 5 ampere discharge for one hour the draw from the battery is only 5 ampere hours, from a fully charged 80 Amp-Hour battery. This will result in only a 6% reduction in capacity. Therefore, don’t worry too much about driving with a discharge for an hour.

If you have a Model A with an original cutout [31]

and generator, it is possible to drive for a long distance and avoid, somewhat, overcharging the battery by a combination of setting the generator to a lower than 10 Amp output and using the lights as a sort of manual charge regulator. Figure 9 Charge/Discharge Rate vs Ammeter Reading shows the relationship between 3rd Brush settings, the charge or discharge rate and current consumed by the electrical circuits in the Model A. To use the chart look to the example shown in the green lines with arrows. Observe your ammeter reading with the Model A running at about 1200 to 1500 RPM. With the 3rd brush set to charge at 8 Amps and the lights and other accessories off, the ammeter reading should be about 8 Amps (assuming that your ammeter is accurate). Now turn the lights on. The ammeter reading will drop to another value. In our example, the reading is then -4 Amps. To find the lighting load, read up from your ammeter reading on the Ammeter scale to “Load in Amps”. Find your brush setting on the left and read across to where the ammeter reading and the brush reading intersect. The value in our

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example is 12 Amps at a brush setting of 8 Amps. Now to find the amount of capacity loss due to this load, simply follow the ammeter reading up to the diagonal line on the chart, then read across to the Rate of Change in Capacity scale on the left side of the chart. In the example, the reading of -4 Amps is the current drawn from the battery, and results in a 5% loss in capacity of an 80 Amp-Hour battery during one hour of driving with the engine RPM of over 1200 RPM. Likewise in 2 hours driving you would remove 10% of the capacity of the battery. Of course you must use some judgment in using the lights as an overcharge prevention method. If you are using the car in a parade or driving in town with many stop lights, this is not a very good idea. In these cases it is best to keep the lights off, and risk some over charging.

Figure 9 Charge/Discharge Rate vs Ammeter Reading

You can also get some idea of the amount of overcharging you are experiencing from this chart. If you have the 3rd brush setting at 8 Amps, then with all of the accessories and the lights turned off your ammeter reading will be about 8 Amps. Reading up the chart from +10 Amps on the bottom scale to the diagonal line you can then see that the rate of overcharge, when driving at a constant 1200 RPM for one hour is 8 Amp-Hour per hour. This means that you are putting in about 10% more charge than the battery requires, resulting in an overcharge condition. While you can operate a Model A using these tools and some guessing about overcharging, it is a better idea to provide some means of controlling the voltage in the generator to drop the charge current to what is required to operate the car. We will now discuss ways to prevent overcharging automatically.

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What to do About Overcharging? This leaves the question; how do we know whether or not the battery is fully charged after a trip, or has it been overcharged? Due to the many factors involved in determining the state of charge or overcharge, the methods available to us are:

a) Method 1 … The “I Don’t Care Way”. I am not going to worry about overcharging, so I simply set the generator charging rate to about 10 Amps, and plan to buy a new battery every 2 to 3 years.

b) Method 2 … The “Engineering Way”. Fully charge the battery, set the charging rate to 5

Amps and drive the car in your normal pattern every day or so for 2 to 3 weeks. Use a hydrometer to check the charge status of the battery. A specific gravity test reading between 1.275 and 1.300 means that the battery is fully charged, and is probably being overcharged. Reduce the charging rate to 4 Amps and repeat the test. If the specific gravity test shows a reading of 1.15 to 1.200 it means that the battery is not being fully recharged and is at about ½ full charge. Increase the charging rate to 6 Amps and repeat the test. In this manner, you will eventually reach an understanding of what setting to make on the generator. However, this will not prevent overcharging during a long trip or be valid if you change the driving conditions.

c) Method 3 … The “Keep It Charged Way”. Set the charging rate to about 6 Amps and don’t

worry about summer or winter under charging problems. Disconnect the battery between vehicle uses and put a “battery minder” on the battery that will ensure that the battery is fully charged when you use it again. This method will not prevent overcharging, and reduced battery life, but it will give you some measure of “comfort”.

d) Method 4 … The “Fix the Problem Way” … There is a way to add a “voltage regulator” to

the generator which will isolate the generator yet prevent overcharging. Nu-Rex makes a cutout with a “Voltage Regulator” built into it and a version that replaces the generator brush cover band. It looks like stock, but functions as a modern car’s regulator. To use this you either replace the cutout on top of the generator with this device or replace the cover band on the generator. Then set the 3rd brush to put out a lot of amperes … 14 or more. The device will automatically sense the voltage of the battery and reduce the battery charge current to what is necessary. The cost is about $75 … cheap insurance for batteries. For info see Appendix 3.

e) Method 5 … The “Change To An Alternator way” … Finally, it is possible to eliminate

many of the problems of the old Model A . The most high performance (and price) solution is to convert the electrical system to use a modern alternator with a built in voltage regulator. There are two possibilities for this, keep the positive ground 6 volt system, or change the electrical system to a more modern 12 Volt system also eliminating the use of inverters.

Generator or Alternator … What are my Choices?

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Figure 10 Generator or Alternator what are the Choices?

The Figure 10 Generator or Alternator what are the Choices? provides the various tradeoffs and costs involved in choosing a generator or an alternator. It is always possible to avoid overcharging your battery with both the generator and the alternator solutions. Your choice of methods depends on how you plan to use the Model A and where you are in the restoration process. There are three situations that Model A owners are usually in. Firstly, you may be starting out with a basket case or a Model A which needs extensive restoration. Secondly, you may own an older restoration that you drive and tinker with. Finally you may be restoring or upgrading an older restoration or a new restoration for long distance touring. How you approach the issue of restoring, upgrading or repairing the Model A charging and generating system depends on you making certain choices along the way. We now discuss the potentials for the battery and charging system in terms of a series of

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decisions and tradeoffs.

How to Choose A Solution to Overcharging The choice of method for making the Model A charging system trouble free depends on your objectives for your car. There are two basic paths for updating your Model A, authentic versus performance. The “authentic” path keeps the Model A looking like what Henry designed and uses the generator as its building block. The “performance path”, installs a modern vehicle alternator, and gives increased charging, as well as a path to the conversion to +12 Volt operation. If you are going to have to replace the generator anyway, the costs involved are approximately the same. All “authentic” path solutions meet MARC and MAFCA judging standards, while alternator versions do not. Both the “authentic” and the “performance” paths can provide automatic overcharge protection. The following paragraphs describe your choices.

Typical New Restoration A new restoration of a Model A may be for “show” or for hobby driving. The choice of charging system for the “show” car is only one. To show the car for points in the MAFCA or MARC competitions you must have a generator. You have some decisions that you can make about cutouts and voltage regulators, but you will have to stick to the positive grounded 6 Volt battery and a generator. The car which is being restored for “hobby” driving has a wider choice of possibilities. The first decision you will have to make is whether to use a generator or an alternator. This decision depends on how authentic you want the Model A to “look” when you lift the drivers side engine compartment hood. An alternator cannot be made to look like a Model A generator/cutout assembly. If you have a good generator, and want to retain the “authentic” look, and you are not going to use a lot of +12 Volt accessories you may want to stay with the good old generator. On the other hand you may want to upgrade your electrical system to have brighter lights, no charging problems, and have a larger variety of +12 Volt accessories, such as high power CB and FM radios, CD players, and even air conditioners available while driving. In this case, you will want to use an alternator.

Older Existing Restoration You may have an older restoration, which needs to have its generator or generating system replaced, or you want to use your old generator but avoid overcharging. On the other hand, you may simply want to upgrade the generating system for more performance, or to use more 12Volt accessories. If you choose the “authentic” path you need to make a decision between the amount of “authenticity” you desire. For the “purest” Model A enthusiast, choose the “I don’t care about overcharging” path and select the stock generator with a stock electro-magnetic cutout. If you are not completely a “purest” you can choose a diode cutout to eliminate sticking contacts. On the other hand, if you want the stock look, and want to prevent battery overcharging choose the path that eliminates 3rd brush adjustments and install a voltage regulator.

New Touring Restoration Some Model A owners will be building a “touring” Model A from scratch, or may be upgrading an older restoration to use for long distance touring. While you can still choose the “authentic” path as discussed above, and can choose a generator with a voltage regulator, it will have limited performance to provide you with long distance touring needs. Most builders of long distance touring Model A’s want high performance, reliability, and elimination of electrical problems. The solution to this is to use an alternator. There is a basic choice you must make when contemplating adding an alternator. You must choose between the use of the Model A positive ground 6 Volt system, or conversion to a negative ground 12 Volt system. Both of these will give better performance, brighter lights, and increased charging capability. The advantage of a 12 volt system over keeping the 6 Volt system is better component ground reliability, increased accessory convenience, and elimination of

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the need for an inverter.

Battery Voltage Batteries are nominally rated at either 6 or 12 Volts, however, the actual battery voltage will vary during the charge and discharge cycles under load. The no load, open circuit voltage of a 6 Volt battery is actually about 6.3 Volts. A 12 Volt battery’s open circuit voltage is about 12.7 volts. The actual Model A battery voltage during discharge will vary depending on several factors, including state of charge, applied electrical load, battery temperature and electrolyte specific gravity. The largest load applied to the battery is the starter motor. The voltage of a 6 Volt Model A battery during starting will be below 6 Volts as shown in Figure 1 Battery Voltage to Starter vs. Engine Turning Rev/Sec. The starting voltage will be below 6 volts and can drop to as much as 5 volts under adverse conditions. Below 4.5 Volts the Model A will probably not start.

State of Charge versus Battery Voltage Temperature and state of charge has the most influence on the ability of the battery to supply the necessary power to the Model A starting motor. The power that is able to be applied to the starter motor is both dependent upon the voltage available at a certain temperature and the conditions of the connections between the starter to the battery and the battery to ground. As the temperature goes down the amount of power required to turn the engine goes up, and at the same time the available capacity of the battery to supply this power goes down. These two factors work together to ensure that a weak battery will fail to start the Model A Ford in winter conditions. Open circuit voltage of lead-acid batteries vary with temperature, electrolyte specific gravity and state of charge. The following table lists open circuit voltage as a function of the state of charge.

Check and/or Improve Your Battery Connections Poor battery connections can contribute to difficulty in starting the Model A Ford, especially if you have a 6 Volt system. Bad connections are generally the fault of having corrosion at the terminals of the battery. Batteries outgas during the charging cycle, causing a gas to escape. This gas interacts with the lead terminal posts to form a white lead oxide which is an insulator, reducing the capability of the terminal to transfer high starting currents. In addition, the gas interacts with the copper wires in the cable to the starter also deteriorating the ability of the cable to carry the current. These bad connections can reduce the battery voltage by ½ Volt or more. This means that the ability of the car to start in cold weather is reduced approximately as shown Figure 11 Effect of Bad Connections on Starting. This chart is not necessarily a worst case condition and is provided as an illustration. The loss of battery voltage that can be applied to the starter motor due to bad connections causes the starter to need more amperage to turn the engine. The effect is to shift the starter motor performance versus temperature curve to the left. The above chart has been constructed assuming that the connection causes a ½ volt degradation in battery voltage during the cranking cycle. These bad connections can cause up to an apparent 40 degree shift in the temperature that the engine can be

State of Charge Open Circuit Voltage 12V Battery

Open Circuit Voltage 6V Battery

100% (SG = 1.28) 12.65 6.32 75% 12.45 6.22 50% 12.24 6.12 25% 12.06 6.03 0% (SG = 1.1) 11.89 5.95

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started at. While a Model A with GOOD connections can be easily started at about 32 degrees F, one with POOR connections may have difficulty in starting below 50 degrees F.

Figure 11 Effect of Bad Connections on Starting

The obvious solution is to clean and tighten all connections. In “Henry’s days” it was recommended

that the terminals (after tightening) be coated with vasoline. [32]

While you can still do this, the gooey mess may be avoided by using modern sprays and/or anti-corrosion compounds available at most auto parts stores. It is important to check the conditions of the starter cable, by pealing back the insulation and checking for green and white deposits on the cable copper wire. Replace the cable if there are signs of degradation. A good insurance to assure a good, high current, connection to the starter is to add a 19 inch long #4 gauge battery cable from ground connection of the battery on the frame to a bolt on the

transmission. A good discussion of this is shown in Les Andrew’s book [33]

.

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Ways to Increase Battery Voltage or Capacity While it is not applicable to the Model A, the following discussion is provided for reference. You can use two batteries to gain more electrical power by wiring the batteries in parallel or in series.

Figure 12 Batteries in Series

As shown here, two 6 volt batteries can be connected in series to form a 12 Volt battery with double the capacity of one of the batteries. In this case a charging system is required which will charge the two batteries as a 12 Volt system. Alternatively, you can remove the batteries and charge them individually as 6 Volt batteries. Be sure to select batteries of the same voltage rating. On the other hand you can get more electrical capacity by connecting batteries in parallel.

Figure 13 Batteries in Parallel

As shown here the two batteries continue to deliver electrical current at 6 Volts, however, the capacity of the system is doubled. One thing to remember is that if one battery is weaker than the other or two unequally charged batteries are connected in parallel, the stronger of the two will discharge into the weaker battery until an equilibrium is obtained.

Battery Ratings There are a number of battery ratings used to provide sizing information to consumers who are buying replacement batteries for automotive use. These ratings, while important in a relative sense, are not absolute in their application to real situations.

Battery Capacity Ratings

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Power ratings are important to understand how to size your battery. To better understand battery capacity one must understand some basic terminology. The electrical current flow to or from a battery are measured in amperes or “amps”. For a battery, the most important number is the “amp-hours (AH) rating”. This means, in theory, that if you had a battery with a 80 AH rating and the load drew a steady 4 amperes, the battery would discharge in 20 hours. However, this rating is only useful in a relative sense. Real batteries are not this efficient. For example, as the battery discharges the voltage will remain steady for only a small percentage of the time, then will drop in an ever increasing amount as the battery discharges, causing the load to demand more current. The battery will discharge at a constant rate for only a period of time, then more rapidly at the end of the discharge cycle. In fact, a fast discharge rate, will cause the battery to produce much less effective power capacity. For example, the same 80 AH battery which fully discharges in 4 hours may only deliver a portion of its available power capacity. Peukert’s Law, developed by W. Peukert in 1897, states that the “real” capacity for a battery decreases as the current drawn from the battery increases. A discussion of Peukert’s Law is found in Appendix 2. Ampere-hours (A·h) is the product of the time that a battery can deliver a certain amount of current (in hours) times that current (in amps), for a particular discharge period at a specified discharge current. This is one indication of the total amount of charge a battery is able to store and deliver at its rated voltage. Historically, battery manufacturers have stated their capacity in Amp-Hours for a constant discharge rate of Amp-Hours/20. This means that an 80 Amp-Hour battery is typically rated to deliver this capacity with a constant discharge current of 80/20 = 4 Amps. However, be careful … the

manufacturers may state different values of current, or more usually, none at all [34]

.

Battery Reserve Capacity Another rating that you see on some automotive batteries is Reserve Capacity (RC) . This is defined as the time in minutes that at a specific temperature a fully charged battery can be discharged at a specific amperage before its voltage drops to a certain value. Typically, this is shown as the reserve capacity (RC in minutes) at 80 degrees Farenheit that the battery can be discharged at 25 amperes before it reaches 10.5 Volts (for a 12 Volt battery). This rating is rarely stated.

Battery Cranking Ratings Cranking Amperes (CA) is used to compare batteries and indicates the number of amperes that a fully charged 12 volt battery at 32 degrees Farenheit can deliver for 30 seconds and maintain at least 7.2 Volts. For a 6 volt battery this is the number of amperes that the battery can deliver at 32 degrees Farenheit for 30 seconds and still maintain a voltage of 3.6 Volts. Cold Cranking Amperes (CCA) are used to compare automotive batteries and indicate the number of amperes a fully charged 12 Volt battery can deliver at 0 degrees Farenheit for 30 seconds and maintain at least 7.2 Volts. For a 6 volt battery this is the number of amperes that the battery can deliver at 0 degrees Farenheit for 30 seconds and still maintain a voltage of 3.6 Volts. Hot Cranking Amperes (CCA) are used to compare automotive batteries and indicate the number of amperes a fully charged 12 Volt battery can deliver at 80 degrees Farenheit for 30 seconds and maintain at least 7.2 Volts. For a 6 volt battery this is the number of amperes that the battery can deliver at 80 degrees Farenheit for 30 seconds and still maintain a voltage of 3.6 Volts.

Types of Batteries There are three basic automotive batteries available on the market today. Conventional flooded electrolyte, absorbed glass mat, and gelled electrolyte also called gel-cells. This section describes these types and provides information on what is good and bad about each.

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Flooded Electrolyte Types Flooded Electrolyte type batteries are the oldest and most common batteries in automotive use. The original Model A Fords were manufactured and delivered with these type batteries. These batteries contain a mixture of about 90% water and 10% sulfuric acid. They provide good capacity at a reasonable price. They come in two sub-types, those with removable caps that require periodic refilling with water, and those newer versions called “maintenance free”. The non-maintenance free original flooded electrolyte batteries are lead-antimony types that require periodic checking and refilling with water to maintain their electrolyte level. You should use distilled water to prevent a buildup of minerals in the battery case. The newer “maintenance free” batteries (easily discernable because they do not have removable caps) are lead-calcium types. These so called maintenance free batteries use less water (but still some), as they are designed to run low on water about the time that they are worn out. These “maintenance free” batteries, when used in hot weather and/or are frequently deep discharge cycled will use more water, and may be weakened or ruined in these situations due to the electrolyte levels dropping below the top of the internal lead plates. Model A owners that do not have a voltage regulator should avoid maintenance free batteries since overcharging will cause them to “boil out” quicker, thus fail sooner. On the “good” side of maintenance free flooded electrolyte batteries, they usually vent less fumes, and therefore have lower rates of corrosion at the battery terminals. For more information visit www.interstatebatteries.com or www.exidebatteries.com

Absorbed Glass Mat Type Absorbed Glass Mat (AGM) type batteries don’t require water since their electrolyte is absorbed in a silica glass matting wrapped around the internal lead plates. AGM batteries are vibration and maintenance free, however, are quite pricey. They generally, deliver higher power and efficiency than gel cell or flooded electrolyte types. This battery type looks more like a Model A battery. None of the Model A mail order parts suppliers offer AGM batteries. For more information visit www.dekabatteries.com

Gelled Electrolyte Type Gel type batteries contain a jellied electrolyte rather than a liquid. Gel cell batteries usually don’t require any water, but if they are discharged at too high a rate, they will lose some electrolyte through out gassing, and will have shortened life. Gel cell batteries are more tolerant of being left partially discharged and they do not self-discharge fast. However, they do not tolerate repeated deep discharge cycles. Gel types require slightly different charging voltages and therefore are more difficult to install and keep charged with typical automotive charging systems. Gel cell batteries cost substantially more than the lead acid types. This battery looks “space age” being constructed as either 3 or 6 cylinders not as a square box. For the Model A owner, this battery type requires a different battery hold down top plate, further increasing the price. The gel cell batteries are offered by some of the Model A parts suppliers. For more information visit www.optimabatteries.com

Automotive Battery Operation The automotive battery is somewhat different than other storage batteries, in that its main load is a quick discharge at high amperages during the starting of the vehicle, followed by a rather slower recharge cycle. This demand is especially hard on the Model A battery, since it has an inefficient 6

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Volt operation, and poor recharge capability and the problem of overcharging unless you have a voltage regulator.

Charging Batteries In normal automotive service a modern vehicle's engine-driven alternator powers the vehicle's electrical systems and restores capacity, used from the battery during engine cranking, while driving. As discussed above in the section on the “Original Model A Battery” the potential to recharge the Model A battery may be limited due to starting conditions, mainly temperature. For the Model A Ford, the original charging system may be deficient when the vehicle is used in winter weather at temperatures below 0 degrees F. Modern alternators can supply a large current to recharge the battery quickly during cold weather, thereby eliminating the problem of cold weather operation. The ability to discharge and recharge flooded electrolyte lead-acid batteries can be limited by battery aging. The main two problems of battery life are, lack of electrolyte due to evaporation, and over charging. Modern battery chargers can be purchased with “taper” charging or two level charging which reduce the charging levels as the battery approaches full charge. When installing a new battery or recharging a battery that has been accidentally discharged completely, one of several different methods can be used to charge it. The most gentle of these is called trickle charging. Other methods include slow-charging and quick-charging, the latter being the harshest. Typically, automotive battery chargers used for recharging batteries that have been discharged do not have an auto – float charging feature and are not useful for maintenance charging. Maintenance charging when the battery is in storage is best accomplished by a “maintenance” charger sometimes called a “battery minder”. These devices have a feature called auto – float which only provides a small charge when the battery needs it.

Battery Charging Voltage Set Points Different battery types have different charging voltage set points and auto-float charge voltage settings.

Battery Charging Current Rate For best battery life, batteries should not be recharged at a rate exceeding 20% of their AMP-Hour rating. The Model A 6 Volt battery is typically rated at 80 AMP-Hour so it should be charged at a maximum rate of 16 Amps. Using a lower charge rate is preferred if you can spare the time. When storing a battery for the winter, a charger with an auto – float charging feature should be used. A typical maintenance type charger for a 12 Volt battery will provide a charge rate of about 1.5 to 2 Amps until the battery voltage has reached 14.4 volts (on average). At this point the internal reference of the charger will change to maintain the battery voltage at 13.2 Volts (on the average). At this lower voltage, a charging current of a few milli-amperes is provided constantly to the battery. At this condition, most batteries can be left charging indefinitely. Usually, maintenance battery chargers have some internal electronic current needs, and do not have a on-off switch, therefore do not leave these devices connected to the battery when unplugged from the 110 Volt home electrical supply or the battery will discharge.

Type of Battery Charge Voltage Set Point Auto-Float Charge Setting Flooded Electrolyte 6 Volt 7.1 – 7.3 6.6 – 6.8 Flooded Electrolyte 12 Volt 14.2 – 14.6 13.2 – 13.7 AGM 12 Volt 14.1 – 14.4 13.2 – 13.4 Gel Cell 12 Volt 13.8 – 14.0 13.2

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Battery Chargers Many battery chargers available have switches that allow charging of both 6 Volt and 12 Volt automotive batteries. Many chargers have switches which allow a high charge rate and a low charge rate such as 15 Amp and 5 Amp. The best charging solution is to use a multi-stage charger with an automated charge regulation that keeps recharging time to a minimum, but prevents overcharging. If you are going to use a gel cell or an AGM battery choose a charger which can provide the proper charging voltage set point.

Battery Maintenance Charger System for the Model A A simple battery maintenance charging system can be added to a Model A Ford to make it easy to connect the maintenance charger when it is garaged for a week or a month between tours. A simple system is shown in Figure 14 Easy Maintenance Charger Installation A battery disconnect switch is installed at the negative terminal of the battery, to isolate the Model A from the maintenance charger ( a good safety item to have anyway). Then two wires are routed to a plastic bracket which will insulate the negative terminal from the Model A. The two studs make an easy place to connect the leads from the maintenance charger. To operate, simply turn the battery disconnect switch to OFF, and connect the clamps to the studs, plug in the maintenance charger and your done!

To install a battery disconnect switch refer to Les Andrews book. [35]

Alternatively battery disconnect switches that attach directly to the battery can be purchased at WalMart inexpensively, however can require some additional cables and brackets to attach to the Model A without interfering with the battery hold down. In addition, to be effective, it is important to make the disconnect easy to use. Since the terminals are always “hot” be careful that they cannot be shorted. Also, these terminals provide a convenient 6 Volt connection for accessories.

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Figure 14 Easy Maintenance Charger Installation

What about Power Converters? While most Model A owners do not have a power converter in their Model A, many of us also have Recreation Vehicles. An RV may be in the form of a trailer, a 5th wheel, or a motor home. If the RV is a motor home, it typically combines the function of engine starting with 12 Volt power to the remainder of the RV. For trailers and 5th wheels, they typically have a separate deep cycle battery system with two or more batteries in parallel to provide more capacity. The RV usually has an Inverter which changes 12 volt DC battery power into 120 Volt AC power and may combine this with a 110 Volt to 12 Volt power converter for converting the RV park electricity input to 12 volts necessary to power the lights and other features. Many of these have the ability to recharge the 12 Volt batteries in the trailer or 5th wheel while plugged into an external 110 Volt source. Be sure that these are not simply trickle chargers running at 2 to 5 Amps, but have an auto – float feature to prevent overcharging. If the RV’s power pack does not feature an auto – float maintenance charger,

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and if you are not going to use the RV for two weeks or a month, you can simply disconnect the battery from the power pack, and connect an external auto – float maintenance charger. During the winter, when the RV is stored outside for several months, it is best to remove the batteries and put them in the garage on a maintenance charger with auto – float. One convenient system, usually not provided by the manufacturer, is shown below.

Figure 15 RV Battery Storage Operation

I installed a 110 volt connection in the battery storage compartment and a quick battery disconnect that you can buy at Walmart or an automotive parts supply retailer. The battery switch (about $15) isattached at the input to the battery system and is connected to the supply cable coming from the RV power pack. This simple modification allows you to not overcharge your RV battery while the RV is not being used for a month or so. I keep a 12 Volt maintenance charger with auto – float in my storage compartment. If I am not going to use the RV for two weeks or a month, I simply plug the RV into an external 110 Volt supply (my house wiring), turn the battery disconnect off, and dig around in my storage bin for the maintenance charger. It only takes a minute or two to connect the maintenance charger and I am then confident that I will not be having to buy two expensive batteries, due to overcharging, in the near future. Just remember to disconnect the maintenance charger and turn the battery switch to ON before the next trip.

Maintenance and Safety

Care and Maintenance Proper care and maintenance can extend battery life. Here are a few things you can do to extend the life of your Model A battery. For more detailed information see the discussion of Battery Life. Always recharge a discharged battery as soon as possible Be sure to check and replace water in non-maintenance free batteries regularly If you are not going to drive the car for a couple of weeks, a month, or longer connect a

maintenance charger (not a battery charger or a so called trickle charger – See Automotive Battery Operation for more information)

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Never leave a battery at a low state of charge for a long period Remove the battery from the car in the winter, when it is not being driven and connect a

maintenance charger to the battery. (See Battery Maintenance for more information) Do not leave a battery with a low state of charge in an unheated garage where they can freeze. A

fully charged battery can survive temperatures well below zero. Clean all connections with sand paper, and keep tight. Apply anti-corrosion protection to battery terminals. Replace any corroded battery cables.

Battery Safety Procedures Batteries can be dangerous. Flooded Electrolyte Batteries (lead-acid types) contain sulfuric acid, which damages almost anything it touches. If you are adding electrolyte to a new uncharged battery use eye protection, rubber gloves, and old clothes. Use baking soda and water to neutralize any spilled acid. Avoid sparks. It is possible for the battery to explode, causing a fire, destroying your Model A, and causing personal injury or even death to you. Batteries vent hydrogen and oxygen gases during normal battery operation, which can explode if sparks from loose connections, jumper cables, or smoking occur nearby the battery. Especially, when charging, near the end of the charging cycle, you will notice that the electrolyte in the battery is bubbling. This means that much gas is being liberated from the electrolyte and this time is especially dangerous. If you are within an enclosed space use a fan to circulate the air around the battery. The following precautions should be used when working with your battery in or out of your car.

Someone should be within range of your voice Have plenty of water and soap nearby incase battery acid comes in contact with your skin,

clothing or eyes. If battery acid contacts your skin, immediately wash with soap and water, and flood the area with running cold water for at least 15 minutes, then seek medical attention.

Wear eye protection, and avoid touching your eyes when working near the battery Never smoke or allow a spark or flame in the vicinity of the battery Never attempt to charge a frozen battery.

To prevent sparks and reduce the probability of a battery explosion during work on the battery, especially if you are going to remove it from the car, do the following;

KEEP METAL TOOLS FROM DROPPING ON THE BATTERY, which can cause a spark if it contacts both the positive and negative terminals.

TURN OFF ALL ACCESSORIES AND SYSTEMS IN THE CAR, to prevent current draw from the battery when loosening or removing the battery terminals.

REMOVE THE GROUNDED TERMINAL OF THE BATTERY FIRST, since any current flowing to devices turned on will reduce the probability of sparking.

DISCONNECT THE GROUNDED TERMINAL OF THE BATTERY WHEN WORKING ON THE MODEL A’s ELECTRICAL SYSTEM. If you are going to do some work on the car, or just want to disconnect the battery to keep it from draining, use the grounded terminal NOT the starter cable to disconnect the battery.

Safety precautions should be used during charging of the battery, either in or out of the vehicle.

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BE SURE THE AREA AROUND THE BATTERY IS VENTILATED. The battery gases can be blown away by a fan if necessary

ADD DISTILLED WATER TO THE RECOMMENDED LEVEL. This helps purge gas from the cells. Do not overfill.

PUT THE CHARGER AS FAR FROM THE BATTERY AS THE CABLES WILL ALLOW. Never place the charger near or above the battery. Do not sit the battery on top of the battery!

CONNECT THE BATTERY TO THE CHARGER BEFORE CONNECTING THE CHARGER TO THE 110 VOLT AC SUPPLY. Connecting the AC supply last will prevent sparking at the battery terminals.

WHEN DISCONNECTING THE CHARGER, DISCONNECT THE AC SUPPLY FIRST, THEN DISCONNECT THE GROUNDED TERMINAL, THEN FINALLY THE POSITIVE (negative for the Model A) TERMINAL.

Battery Testing We live in a throw away society and you may never need to test a battery. However, to make this report complete I will list methods you can use to test a battery to gauge its ability to perform. These testing methods are specific to a flooded electrolyte (lead acid) battery. Battery tests can be made to determine the state of charge, if the battery is worn out, and to reveal the amount of remaining life. [36]

State of Charge Tests The state of charge can be tested by measuring the specific gravity or by measuring the open-circuit voltage of the battery.

(1) Open Circuit Voltage Test To do this test a volt meter with a range that includes the standard voltage of the battery, 12.7 Volts for a 12 Volt battery and 6.3 Volts for a 6 Volt battery. A digital volt meter that reads and displays voltage with an accuracy of 0.01 is preferred. To make the measurement place the volt meter probes between the individual cells of a fully charged battery. If there is no access to the individual cell terminals, this test cannot be performed. A recently charged battery will have a “surface charge” giving an abnormally high reading. To avoid this abnormal reading, dissipate the surface charge by turning on the lights of the car for a few minutes. Alternatively, you can wait an hour after charging the battery. With the volt meter connected across the terminals of the cells, the reading should be 2.05 to 2.15 volts. Between 2.03 volts and 2.05 volts the battery needs more recharging. Below 2.03 volts the battery needs recharging. Applying the volt meter across the battery from the + terminal to the – terminal we can get a “quick” look at the battery state of charge. This test is not conclusive since one of the cells may substantially lower than the others or failed. However, a reading of 6.15 to 6.45 volts means that the battery is fully or nearly fully charged. A reading between 6.09 and 6.15 means the battery may need charging. Below 6.09 Volts the battery needs recharging. (2) Hydrometer (Specific Gravity) Test To do this test you will need a hydrometer. They can be purchased from auto supply stores. You cannot do this test on a maintenance free battery, since you will not have access to the electrolyte. Do not make this test after water has been added to the battery, since the water will float on top. Remove the vent plugs and draw some electrolyte into the tube to cause the float to

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rise in the tube. Read the specific gravity on the scale. Note the temperature of the sample and use the compensation table to get the specific gravity. After noting the specific gravity compress the bulb and return the sample to the battery. Batteries with compensated readings of 1.250 to 1.295 with a variation between cells of less than 0.015 is considered fully charged. If the reading is 1.225 to 1.250 the battery should be recharged. If below 1.225 the battery should be further tested to check if it is worn out and needs replacing.

Battery Capacity Testing Batteries were capacity tested as a routine matter in the 1930s through the 1950s. While not in vogue in this “throw away society” we live in, many of the old methods and equipment still exist. If you have an antique “Battery Capacity Tester” you can make the test with the outside the car. If you do not, a subjective cranking test can be accomplished.

(1) Testing with a Battery Capacity Tester There were several different types of battery test equipment available. Some were built into battery chargers and others were hand held devices. Some just had “good”, “poor”, or “replace” colored bands. Others showed percentage of capacity remaining. In all cases, the test was not all that accurate, but instead gave a relative reading. In the “old” days if the tester showed “poor” or about 60% capacity during the test, it was probable that the car would not start in cold weather. Basically, the capacity tester consists of a carbon pile rheostat which can be adjusted to discharge the battery at a predetermined rate, and an ammeter to read discharge rates, and a volt meter to read battery voltage. The rheostat setting is selected for the battery design used, and was determined by the battery amp-hour rating. Typically, this meant that the discharge rate was 25 times the number of positive plates in the battery. The Model A had 13 plates, of which 7 were positive. Thus the discharge rate for the tester would be set at 175 Amps. A resistance of 6 divided by 175 = 0.0348 Ohms would give the test adequate discharge. With the setup in place, connect the tester across the battery terminals. The meter reading should hold 5.4 volts for a battery in good condition. If the battery reading is below 5.4 volts but above 5 volts the battery has lost up to 40% of its capacity and should be replaced. Keep the tester connected for a few seconds, if the tester shows initially good, then drops back rapidly the battery is defective and will need replacing. If the tester voltage shows less than 5 volts the battery needs replacing. (2) Capacity Test While Cranking the Engine Ok, what if you don’t have a battery test setup? A capacity test can be made on the Model A with the battery in the car. To make this test a volt meter is required. A digital volt meter that reads and displays voltage with an accuracy of 0.01 is preferred. Run the car until the

temperature is in a normal operating range. Turn the ignition switch to OFF. [37]

With the volt meter connected across the battery terminals, crank the engine for about 30 seconds. If the engine cranks at a good speed and the voltage does not drop below 5.4 volts the battery can be considered to be in good condition and at or nearly at full charge. If the voltage is below 5.4 volts and especially if it approaches 4.5 volts the battery capacity may be low and the battery may need replacing. However, it also may mean that the battery state of charge is too low, or that the battery terminals are corroded, or other problems, such as a faulty starter.

Battery Charging in the Vehicle

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The 6 volt positive grounded battery in the Model A can be charged while in the vehicle. There are two ways to accomplish this. The safest method is to isolate the battery from the car, and connect the charger directly to the battery. A less safe, but quick method is to connect the charger to the starter input bolt and a bolt on the engine. This approach avoids removing the floor boards.

Safest Charging Method The safest method is to remove the horizontal floorboard just in front of the driver’s seat. Then disconnect the positive ground cable to the frame, and then the negative cable to the starter.

Figure 16 Safely Charging the Battery in the Vehicle

With the battery isolated, connect the charger with the positive cable to the positive terminal and the negative cable to the negative terminal on the battery. Be sure to observe the safety considerations when connecting the charger to the battery. Open the windows and the doors of the Model A before connecting the cables to vent any gases. Check the battery electrolyte level, and top off any low electrolyte level cells with distilled water. Connect the positive charging cable first, then the negative cable, and finally plug in the battery charger.

Quick Charging Method The 6 volt positive grounded battery can be charged without removing the floor boards, by connecting to the starter terminal located in the engine compartment near the steering column. This means taking precaution to turn OFF any accessories, lights, and the ignition. Care must be taken when connecting the NEGATIVE charging cable to the starter bolt, to ensure it does not get grounded on the starter push rod or the steering column. Wrap electrical tape over portions of the clamp which can become grounded.

Jump Starting When jump starting the Model A be careful to not create sparks near the battery. Use a heavy wire jumper cable set since 100 to 200 Amps will be flowing through them. For a positive grounded Model A (the stock arrangement) use another Model A with a 6 Volt battery. The use of another

Model A may not work. [38]

There is so much current flowing through the jumper cables that the voltage drop due to too small of jumper cable wire causes the starter motor to turn too slowly. In this case use a modern car with a 12 volt battery. It will not be necessary to start the modern car. Make sure that the terminals are correctly connected according to polarity. The following procedure should be used for connecting the two Model A’s or a modern car to a Model A, to perform the jump start. Since the battery is under the floor boards and not easily available, we can use the starter

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terminal on the driver’s side of the Model A to connect the jumper cables. Connect the “good Model A” cables first. Connect the NEGATIVE Jumper cable to the starter

terminal. Be sure to wrap some insulating material, heavy cardboard, or plastic around the clamp to ensure that the clamp does not contact the starter push rod, or the steering column. Then connect the POSITIVE Jumper cable to a clean (not painted) portion of the Frame or to an engine bolt.

Now connect the “Model A needing starting”. Connect the NEGATIVE Jumper cable to the starter terminal. Again, be sure to wrap some insulating material, heavy cardboard, or plastic around the clamp to ensure that the clamp does not contact the starter push rod, or the steering column Then connect the POSITIVE Jumper cable to a clean (not painted) portion of the Frame or to an engine bolt.

After starting, remove the cables in the reverse order to the above paragraphs. For a 12 Volt NEGATIVE grounded system (modern vehicles) just reverse the procedure; Connect the “good vehicle” cables first. Connect the POSITIVE Jumper cable to the battery (+)

terminal. Then connect the NEGATIVE Jumper cable to a clean (not painted) portion of the Frame or to an engine bolt well away from the battery.

Now connect the “Vehicle needing starting”. Connect the POSITIVE Jumper cable to the battery (+) terminal. Then connect the NEGATIVE Jumper cable to a clean (not painted) portion of the Frame or to an engine bolt well away from the battery.

Battery Storage

Winter Storage The best approach is to remove the battery from the car and connect it to a maintenance charger. Keep the battery cold, storage in an unheated garage is preferred to storage in a heated basement. When connecting one or more batteries to a maintenance charger use the following procedure. Charge each battery fully. If the battery has been in the car recently simply connect it to a

maintenance charger. If the battery has been sitting for a month or two, charge it with a battery charger before connecting the maintenance charger.

Connect the batteries in parallel (that is plus terminal to plus terminal and negative terminal to negative terminal) using cables with alligator clips. It is not necessary that these cables be heavy, any 12 or 14 gauge wire will do.

Connect the maintenance charger to one of the end batteries observing the proper polarity. Plug in the maintenance charger to a 110 volt AC supply. The maintenance charger current will be a few hundred milliamps. Check the charger for

multiple battery charging.

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Appendix 1 … Battery Availability The following data has been gleaned from various catalogs and by checking retail stores.

(1) Shipped DRY – No electrolyte included (you must do this yourself) (2) Shipping Charges Extra $10 to $36 depending on retailer (3) Requires a different battery bracket top piece at $15 each.

Battery Availability

Capacity CCA Reserve

Retailer Battery Type Volts AH Amps minutes Notes Price

Bert's Model A Ford Script - Original 6 ?? ?? ?? (1)(2) 125.00$

Standard 6V 6 ?? ?? ?? 56.00$

Optima - Gel Cell 6 ?? ?? ?? 98.00$

Optima - Gel Cell 12 ?? ?? ?? (3) 125.00$

Bratton's Ford Script - Original 6 120 ?? (1)(2) Not available

MAC's Ford Script - Original 6 ?? ?? ?? (1)(2) 165.00$

Snyder's Ford Script - Original 6 120 ?? ?? (1) 135.00$

Mike's Optima - Gel Cell 6 ?? 750 160 (3) $ ?

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Appendix 2 … Capacity versus Discharge Rate From Wikipedia, the free encyclopedia on the web at Wikipedia.com Peukert's Law, developed by the German scientist W. Peukert in 1897, expresses the capacity of a lead-acid battery in terms of the rate at which it is discharged. As the rate increases, the battery's capacity decreases, although its actual capacity tends to remain fairly constant. Peukert's law is as follows:

where:

C is the capacity according to Peukert, at a one-ampere discharge rate, expressed in A·h. I is the discharge current, expressed in A. k is the Peukert constant, dimensionless. and t is the time of discharge, expressed in h.

However, more commonly, manufacturers rate the capacity of a battery with reference to a discharge time. Other researchers have extended Peukert’s Law to use Amp Hour ratings. Therefore, the following equation should be used:

where:

H is the hour rating that the battery is specified against C is the rated capacity at that discharge rate. I is the expected discharge rate in Amps

Note that no longer Cp appears in this equation, which is good since battery manufacturers do not

provide this rating. For example; take a typical Model A battery. The Model A lead acid battery typically has a Peukert’sConstant of 1.3 and has a Amp-Hour rating of 80. AH. For an ideal battery, the constant k would equal one, in this case the actual capacity would be independent of the current. For a lead-acid battery, the value of k is typically between 1.1 and 1.3 however. The Peukert constant varies according to the age of the battery generally increasing with age.

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Technical Applications Peukert's Law cannot be applied across different battery chemistries, or even from one battery structure to another in the same chemical class. The Peukert factor for a particular battery chemistry and stucture can only be used to predict performance within that group of batteries. Example 1 Given a Lead Acid class of battery that has been previously tested to determine a Peukert's Exponent of 1.3 you can make the following calculations to determine the possible performance at different discharge rates. At an advertised rate of 200 Ah the battery will produce 200 A·h over a constant period of 20 Hours. Simply put, the battery was designed to discharge at the rate of 10 Amps for 20 Hours. Amps (10) times Hours (20) equals Amp Hours (200). Since everyone sees battery capacity as somewhat likened to water in a glass, one might want to think that the A·h capacity of a battery would remain constant while the time and discharge rate remained connected in a linear fashion. This is not the case. Given this same battery under a load of 20A you would think that it would operate for 10 Hours, but it will not, it will operate for only 8.1 Hours. The resulting Ah rating falls to 162.5Ah. An apparent loss of 37.5 Ah or 18.75%. This is the effect of Peukert's law on this particular battery chemistry and structure. Now we have a new starting point. 20A for 10 Hours. If we double the discharge rate to 40A can we expect to see a predictable loss of 18.75%? At 40A we would expect our Peukert adjusted 162.5 A·h battery to operate for 4.06 Hours. Since we already experienced a loss of 18.75% in the first test, after doubling the discharge rate, lets adjust our capacity in this test to see if it falls in line. 18.75% of 162.5Ah is 30.47 A·h. Subtracting this from 162.5 A·h leaves us 132.03 A·h. How close to the mark is our "guestimate"? Pretty darn close. In actuality the battery will test out at 131.96 A·h. Now we have a new mark, a 40A discharge rate produced 132.03 A·h on paper, and very close to that in the real world. If we go to 80 Amps can we expect the same loss of 18.75% from the Peukertsadjusted 132.03 A·h battery? Mathematicaly we should see 107.29 A·h. In the real world you will see 107.18 A·h. Nearly on the mark! You can now simply create points on your graph for any given battery by testing once, and then extrapolating using the above process. Note that this holds for lead-acid batteries and not other types. References W. Peukert, Über die Abhängigkeit der Kapacität von der Entladestromstärcke bei Bleiakkumulatoren, Elektrotechnische Zeitschrift 20 (1897) D. Doerffel, S.A. Sharkh, A critical review of using the Peukert equation for determining the remaining capacity of lead-acid and lithium-ion batteries, Journal of Power Sources, 155 (2006) 395–400

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Appendix 3 … Voltage Regulators & Alternators Voltage or Current regulators can be used to reduce or eliminate overcharging in a Model A battery. These devices are available from various Model A parts suppliers. This report has not evaluated any of these devices and only provides information that the parts suppliers have in their catalogs. In addition, to prevent overcharging, you can replace your stock Model A generator with a modern alternator. Model A parts suppliers can provide you with these devices. There are a couple of ways to go if you are going to make this substitution.

Voltage Regulators There are a couple of types of these devices available.

Cover Band Mounted Internal Generator Voltage Regulator This type keeps the Model A generator and cutout “pristine”. It keeps the look and operation of the generator and cutout the same as the stock version. What you do is purchase a replacement generator band (the cover that goes around the back portion of the generator). Mounted to the inside of this band is a solid state voltage regulator. This system is made by Nu-Rex. You must still use a cutout, to prevent a connection to the generator while the Model A is not running and can be of the stock relay or diode type. This Voltage Regulator is limited to use with 6 Volt Positive grounded systems. This type of voltage regulator cannot be used with the 1928 “power house generator”. If you want to install a voltage regulator for use with a “power house” generator you will need to use the cutout mounted regulator discussed below. When used with a stock generator, this regulator will “electronically” move the third brush as the voltage demand changes. At night when the lights are on, this will automatically increase the charging rate. The ammeter should read Zero after the battery is fully charged. This device senses the battery voltage and automatically changes the charging rate so that the battery is not overcharged. The manufacturer claims that you will have stronger lights, and horn performance. [39]

According to the manufacturer, you will have higher charging rates at slower speeds. [40]

Cutout Mounted Generator Voltage Regulator This type keeps the Model A generator looking “completely stock” and you do not have to replace the generator brush cover band. It will work with the 1928 “Power House” generator. What you do is purchase a replacement cutout voltage regulator. The new cutout voltage regulator, while looking completely like a stock Model A Ford cutout, has a modern voltage regulator built into it. This device is also manufactured by Nu-Rex. The Model A electrical system MUST BE Positive ground. To use the voltage regulator you set the generator charging rate high then the voltage regulator will automatically adjust the actual rate to what is needed. This type comes in three versions: #1 for use with stock Model A generators #2 for use with a generator has wires coming out of it instead of a post #3 for use with a 12 Volt Battery if you have a 6 Volt generator This type is includes a diode as a cutout, and therefore eliminates the old Ford mechanical relay system with its tendency to have “sticking generator contacts”.

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Suppliers of Voltage Regulators Almost all of the mail order Model A parts suppliers can supply these voltage regulators. The following chart shows as of December 2007 the various suppliers. A visit to the website of Nu-Rex, the manufacturer of these voltage regulators does not show these devices in their on-line catalog or provide any technical specifications.

Alternators For more performance the “ultimate” generator replacement is to use a modern alternator, which replaces the entire generator, voltage regulator and cutout system in the Model A. There are advantages and disadvantages to making this replacement. The most obvious downside is that the “look” of the alternator is completely different than the generator/cutout of the original Model A Ford. The second downside, is that if you have a working generator, the change to an alternator is costly, and your “good old” generator will be sitting useless on the shelf in your garage. On the other hand, an alternator can eliminate the problems associated with the original Model A charging system, and prevent overcharging. There are two ways to go when considering an alternator solution. You can keep the positive ground 6 Volt system, all of the lighting, and accessories of the original Model A, by installing a new specially built or modified older alternator that can operate with the 6 volt positive ground system and battery. Alternatively, you can modify the Model A’s electrical system to 12 Volt negative ground and use a modern alternator to power it.

Supplier Type Price Bert’s Cutout VR $75 Mike’s A Fordable Parts Cover Band VR $50 Mac’s Cover Band VR $67

Cutout VR $69 Snyder’s Cover Band VR $50

Cutout VR $63 - $69 Bratton’s No longer carries VRs

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APPENDIX 4 … A Short History of Generators and Regulators This appendix is provided to give some background to the discussion of the Model A generator system, and why, and how it was developed.

Early History of Electric Power Generation for Automobiles Early manufacturers of automobiles, wanting to provide electric lighting for their cars experimented with various means of generating and storing electric power. Batteries were well known by 1903 and were available in low enough voltage that could provide lighting. Generating an electric current from a magneto, driven by the engine (called a dynamo in those days) was well known. Electric power generators with series, compound, and shunt wound configurations were also known. These generators, operating at constant speed could easily generate the power. However, the automobile did not operate at a constant speed, and the problem of regulating the power to provide a constant voltage or current eluded the manufacturers for many years. Early generators, which provided current at ever increasing values as the engine increased its revolutions per minute, caused the lights to either burn dimly or so bright that eventually they would burn out. The earliest versions, 1903 to 1905, of a generator current regulator were mechanical centrifugal governors using slipping clutches. These were largely unsuccessful until 1908 when a few regulators of this type were added to expensive automobiles. The advent of the electric starter, and its need for stored battery power, caused a flurry of activity in the automotive industry to develop an electro magnetic regulator system. The first practical design to reduce the charging current as the battery became fully recharged was the Bijur Voltage regulator [41]

. The Bijur regulator used an electro-magnet winding and a pivoted armature which used a spring and a set of contacts which vibrates as long as the Voltage is high enough to energize the magnet. The decrease in the amount of current was in proportion to the number of pulsations per minute of the regulator. By 1912 the industry had developed a means to weaken the excitation of the generator fields to cut down the current as the engine increased RPM. Eventually, two types of regulation developed, they were called external and inherent. The first type to develop was an external regulation method based on the Bijur which used electro-magnetic relays to cause a vibration which rapidly closed and opened the current flowing through the fields as the generator built up speed which caused the current to remain constant while the voltage varied according to a set point. The second type caused the current to vary while the voltage remained constant. The early vibrator regulator types, which worked, had a flaw. If the points stuck open the generator could burn up, if they stuck closed, the generator (attempting to be a motor) could run the battery down. At that time, the notion of a cutout in addition to the regulator had not developed. A few of these “vibrator” types were found on the more expensive cars. In turn, the industry sought a better means of regulation that did not require a separate vibration unit, which in those early days proved to be somewhat unreliable and tricky to set and maintain. Experiments and inventions yielded two methods inherent to the generator. One inherent means of regulation of the current was the so called bucking coil windings and the other, more common, was called 3rd brush regulation. All generators of these early days relied upon an electro-magnetic relay to “cut out” the generator from the battery when the car was either parked or traveling at a slow speed. During the period from 1912 into the early twenties manufacturers continued to experiment with various electrical power starter and generator configurations. Common versions were either combination generator/starter units and those with separate starters and generators (called two unit systems). Many of the component manufacturers such as Delco, and Northeast offered both. During this period, General Motors offered cars with both kinds of systems, while the Dodge Brothers

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offered only the single unit design. Ford, however, shunning the self starter, offered neither until 1919. The 1914 Cadillac, Hudson, Olds, Packard and Oakland offered a Delco Self Starter combined with a generator, and used a mercury rectifier composed of a plunger which dropped into and was pulled out of a mercury reservoir and was operated by an electro magnet. In 1915 – 1916 the Delco starter/generator used a mechanical regulator as the mercury type proved to be prone to failure. Beginning is 1917 Delco changed once again to add a 3rd brush to the generator section of the starter/generator, by 1921 a thermostatically controlled bi-metallic regulator was used briefly. Finally, by 1923, the industry separated the starter and the generator into two separate units and the 3rd brush generator became the pseudo standard. Ever the innovators, the Dodge Brothers in 1914

offered a low cost car with a self starter, a 12 Volt battery system [42]

, and a 3rd brush generator which was to be set to charge at 7 Amperes on the average. The problem of current regulation in automotive generators persisted for the next 50 years. Various early external means divided into voltage and current regulators all based on the vibrating relay concept, while inherent to the generator means of regulation settled in on bucking coil windings for 4 pole (4 brush) generators and a variation on the two pole (2 brush generator) called 3rd brush regulation. While none of these methods were really satisfactory as a permanent solution, the industry by the late teens and early 1920’s settled in on the 3rd brush generator regulation as a pseudo-standard. Early versions of the external constant current and constant voltage regulators were unreliable and failures caused the generators that were attached to them to burn up. Many of the more expensive makes, that had higher current and reliability requirements continued to use external current or voltage regulators in combination with the 3rd brush two pole generator. The 4 pole generator with external regulation also continued to be used, especially with the single unit starter – generator.

The Problem of Overcharging and Power Regulation The problem of overcharging the battery in early automobiles was well known to automotive electrical engineers prior to 1920 and well into the 1930s. While early versions of various generator regulation means were unreliable, they persisted throughout the teens and into the twenties. Expensive automobiles used them as part of the starter/generator system (Delco) or as stand alone regulators, used in combination with current regulators, prior to 1926 by both Westinghouse and

Delco. [43]

Ford did not utilize an external means of regulating the generator output until 1935 when it introduced a two stage current regulator, and finally in the late 1930s introduced a voltage regulator to prevent overcharging. The reason that an unregulated voltage could be used on low performance cars was that the roads of the day prevented high speeds, therefore limiting the speed of the generator. In addition, long distance driving had not yet become fashionable. Combining these factors meant that overcharging could be managed by seasonally adjusting the charge rate, and owners could manually adjust their generator charge rate to suit their driving habits. By the mid 1930s this method had proved impossible to maintain, and the industry returned to the vibrator voltage and current regulation first invented in 1908 to 1912. By the 1950s Ford was using a three component regulator, which combined a cutout, a current regulator and a voltage regulator in one box, usually mounted on the firewall.

The Advent of the 3rd Brush Generator and Regulation

Eventually the automotive industry settled on the most reliable means of starting and power generation methods. The industry selected the two unit starter – generator combination that we have today. Except for the more expensive cars, the 3rd brush regulation became the most commonly used means of regulating the current in the generator in the 1920s. The Model T and the Model A

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were users of the 3rd brush generator without an external vibrator regulator. While some manufacturers continued to apply external vibrating current or voltage regulators to their systems the most common designs did not, thus requiring the owner to make seasonal and driving habit 3rd brush setting changes periodically. Literature of the time, shows that one of the most prominent discussions was “where and how to set the 3rd brush”. There were many theories and old wives tales

on how set the 3rd brush. The problem with regulation of the generator output versus automobile speed is shown in Figure 17 Generator Output vs MPH with various regulation. Most cars of the early twenties used 3rd brush generators with regulators that developed their maximum current output at about 25 MPH and as shown were capable of about 15 to 18 Amps at that speed. By the 1930s the need for more amperage increased the maximum current to about 25 Amperes. The Ford Model A generator was capable of 22 Amperes, the green line on the chart, but Ford Engineers recommended settings of half or less of that amount.

Figure 17 Generator Output vs MPH with various regulation

As shown in the blue dotted line, the engine speed builds up the current produced by the generator after the cutout connects the generator to the battery. Without regulation of some form the current produced will increase, being forced through the battery and the electrical circuits, burning out components and overcharging the battery. The chart, concentrating on the 3rd brush design

eventually used on the Model A, shows the operation of a 3rd brush generator with and without

external regulation. Automobile speeds in those days were typically below 40 MPH, the 3rd brush generator in low cost cars could be used without any further voltage regulation. The solid black line shows the relationship of automobile speed to generator output. Typically, the designs were made to peak at about 15 Amperes at 25 MPH and then fall off as shown as the engine speeded up. For expensive cars, such as the Packard, with more accessories and power demands, the manufacturer would add a vibrator current regulator and a voltage regulator to cause the generator to have a constant current, as shown with the red line after speeds of 25 MPH or so and reduce the charging when the battery became fully charged. Eventually, the systems prevalent on the more expensive

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cars was adopted by all manufacturers, including Ford. By 1950 most manufacturers provided adequate automatic battery charge protection for overcharging. The Model A 3rd brush generator was basically the same as the Model T generator used in the later part of the 1920s. As shown in Figure 17 Generator Output vs MPH with various regulation , the Model A generator was capable of about 22 Amperes of current output, however typical settings were much less than that as shown by the dotted black line. The Model T and the Model A battery charging system used a “pure” 3rd brush system without any external regulation. While this was adequate for most driving habits of the day, the high constant current output overcharged the

batteries. This problem continued to plague the owners of Model A cars then and still today [44]

. As will be discussed below, the Ford Motor company eventually responded to customer concerns about battery overcharging, the difficulty in manual adjustment, peer pressure, and the continuing requirement for more power to be developed, by introducing external regulation.

Charging Current Regulation Charging current from most generators of the 1920s and early 1930s were of the constant current type. Overcharging of the battery and electrical system problems and concerns prompted the automotive industry to return to some form of generator voltage regulation. By the mid 1930s most of the manufacturers had added some form of regulating the charging current that would taper off the charge current to the battery as the battery became fully charged. There were several types of voltage regulation developed during this period. The interest in the earlier 1912 to early twenties vibrator types revived, as well as types that used new techniques. Figure 18 Early Voltage Regulation Operation shows the basic method of voltage regulation applied in automobiles developed soon after the Model A.

Figure 18 Early Voltage Regulation Operation

The regulation of the charging current is shown in the lower part of the diagram. Without voltage regulation of the charging current the generator charging current is applied to the battery constantly as long as the vehicle is operating above 10 MPH. Two of the many kinds of voltage regulation are shown. All types of charging regulation are caused by reducing the field voltage developed by the

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windings of the generator. The black line shows a 3rd brush generator with a vibrator type of voltage regulation. The red line shows no regulation, and the blue line shows a two step relay type regulator used in early Fords after 1935. The upper part of the diagram shows the battery charge condition as time increases from the starting of the car. Initially, the battery charge decreases to some value below 6 Volts depending upon how much charge is taken from the battery and the initial state of charge of the battery. Once the car has been started and the cutout has closed, the generator charging current is applied to the battery and the voltage of the battery begins to rise. Eventually the battery regains its charge and its voltage

approaches the open circuit voltage of 6.3 Volts [45]

. Eventually, the battery becomes fully recharged. It is this point that the regulation of the charging current becomes important to prevent overcharging. Notice that if the field voltage in the generator is not reduced the charging current (the red line) continues to attempt to charge the battery at the Ampere setting of the 3rd brush causing the overcharging. If a vibrator type of regulator is employed, as the battery voltage approaches 6.3 Volts an electro-magnetic relay is energized pulsating according to engine speed, and causes the field voltage to collapse reducing the charging current to zero. If a two step regulator is used, when the battery voltage reaches a certain set point, usually slightly above the open circuit value of the battery, a resistance is applied to the field winding, reducing the current and causing the generator current to be reduced to a much smaller value. Either of these approaches, and there are more, will reduce or eliminate battery overcharging.

Historical Electrical Generation at the Ford Motor Company The early Fords had no electrical system except for that required to provide the ignition. This system was a magneto system, which was kept from the earliest Ford cars until the end of the Model T production in 1927. Early designs used 12 to 16 Volt magnetos, which were eventually revised to the 18 Volt design. The unregulated magneto could provide electric power to run lights with “good” illumination at 8 MPH and full candle power at 12 MPH. As the speed went up it was possible to burn out the lights. Many owners added a battery to run the lights and recharged it manually, since

the car had no generator. For $85 [46]

you could add a Westinghouse 12 Volt starter [47]

, battery and lighting power system. For $5 you could add a Double EE charger to charge a 6 volt battery from the magneto. The Ford Model T after 1919 was the first Ford Model to have a self starter. Driven by the wide spread use of the Model T in the 1st World War, Ford moved to add a self starter to the original design of the “T” and to improve the overall design. The Ford Model T, manufactured after 1919,

had a self starter and had an electrical design [48]

with a 6 Volt negative grounded battery, which supplied a 98 Amp hour cranking capability for 20 minutes. The starter had a cranking capability requirement of 120 Amps at 5.2 Volts, which yielded an engine speed of about 150 RPM (2.5 RPS). The lighting capacity was 5 Amps for 17 hours. Ford manufactured its own generator, applying it to the Model T manufactured after 1919. This generator was not the same as the one used in the Model A. The Model T generator was a 4 pole design with a 3rd brush. The Model A electrical design followed closely the Model T design, except for a few requirements. The Model A changed the polarity of grounding the battery from negative to positive, following the practice of the times and changed the design of the generator. The Model A version is a 2 pole design with the 3rd brush. It typically had a maximum current of 22 Amps and is shown with the

green line. Model T and Model A owners were admonished to set the 3rd brush well below this current level.

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The Development of the Modern Charging System Today we do not think much of the battery and charging system, since batteries today are inexpensive, and last 5 years or more. Likewise, the modern alternators found in almost all modern cars are reliable and easy to service and replace. The operation of these electrical devices in our highly sophisticated cars with computers and advanced electronic devices is automated, and we rarely consider their use or how they were developed. To put the Model A electrical power generation operation in perspective we will provide the reader with a short history of the development of the modern battery charging system.

Figure 19 History of Modern Charging Systems

The modern charging system has had only three major evolutions. Two of these evolutions came after 60 years of the use of the first. The evolution of the need for “on board electric power” caused by the needs of the motoring public, the automotive industry evolved the current battery plus generator (or alternator) system. With the future advent of the fuel cell for motive power, this may soon change. Soon after the development of the motor car in the 1880s, the motoring public began asking for

electric lights for night driving, and a self starter. [49]

The earliest solution to these needs utilized acetylene lamps and mechanical starters of various types. The first lighting system was acetylene lamps, but these were soon destined for the scrap pile due to the time consuming task of purging the gas lines and lighting. Soon dry cell storage batteries and wet cell rechargeable batteries appeared. These rechargeable batteries were a pain, since they would require removal from the car and recharging by an external battery charger. Self Starters The earliest self starters were mechanical devices. Electric motors, lead cell electrolyte batteries, and electric generators were known to the early automotive engineers prior to 1900 and early attempts to work out how to combine these into a practical system needed a new invention. When a motor was run to start the car, it would consume most of the power of the battery. The basic problem was how

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to recharge the battery onboard the car. Generators worked fine at a constant speed, but when the speed was increased, while driving, the generator field voltage rose so high that the generator would burn out. A form of regulation was required to make the electric system on a car be practical. Various mechanical means of generator regulation, using centrifugal devices, and slipping clutches

were tried as early as 1903. [50]

No practical version emerged until 1908. The mechanical regulator had a brief usage time, but by 1907 to 1910 the engineers had worked out an electro-magnetic means. The concept of a vibrating set of points which interrupted the flow of current through the field windings and caused the collapse of the generator current was invented. This invention caused the self starter, generator, and battery combination to become standard, which essentially continues today. Beginning in 1912 to 1914, the automotive industry abandoned the early mechanical means of self starting the car and soon adopted the electric self starter. These new self starters began to appear on expensive and low cost cars. Henry Ford, however, shunned these improvements for nearly 7 years, claiming that there was no real need for a self starter. Finally, in 1919 the “ Improved Model T ” was introduced with a self starter and electric lighting. Prior to that owners had to modify their cars themselves to include these features. This was not cheap, Westinghouse offered a self starter/electric light system with a generator and battery for $85 in those days dollars, a whopping 25% of the cost of the automobile originally. Batteries Batteries found their way onto automobiles before 1900. Electric Cars and electric lighting was common from 1900 on. Early batteries had to be charged by an external battery charger until the advent of the automobile generator after 1903. Batteries were to be found in 6, 12, and 18 volt versions, with varying capacities. Two standards emerged by the late teens, 6 volt and 12 volt versions. The 12 volt battery lasted until late 1925 when Chrysler changed the venerable Dodge 12 volt design back to 6 volts. The 6 volt battery standard continued for 28 years until the early 1950s. Ford finally put a battery on the Model T, after much customer pressure, in 1919. This battery was a 6 volt design with 80 Amp Hours of capacity. The Ford Motor Company, in keeping with Henry Ford’s policy, made its own battery becoming the only automobile manufacturer to do so. The Ford Model T battery is the same battery that is found on the Model A. The battery in the Model T was negative grounded. For some unknown reason, Ford engineers changed to positive grounding with the Model A. The 6 volt battery design, with positive grounding persisted until the positive ground was changed to negative in 1949. The most common battery design after 1925 was 6 volts with either positive or negative grounding.

General Motors started the modern configuration [51]

in 1953 when it introduced the 12 volt negative grounded battery on Buick, Cadillac, and Oldsmobile. Quickly, the other manufacturers completed the change over to the new 12 volt negative grounded standard by 1956. Ford made its change over in 1956. Generators Many different types of generators were developed and tried. After about 10 years of development, the 3rd brush generator emerged as the design of choice for a large part of the automotive industry. This was driven by the development of the regulator. A wide variety of regulation means were developed by the automotive industry over the period 1912 to 1920. Most of these utilized some form of vibrating relay. These devices both constant current and constant voltage types, had a common problem. They would either fail closed, causing the generator to drain the battery when the car was stopped, or fail open causing the generator to burn up. The industry quickly sought a new design, inherent in how the generator system worked. The most used solution was the 3rd brush

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generator, which had brushes to control the charging current not relays which could stick or fail. Themanufacturers of generators, Northeast, Leese-Nevelle, Delco, Dyneto, Westinghouse, Atwater-Kent quickly went to work perfecting the 3rd brush design. Some, such as Delco and Bijur offered various improved constant voltage regulators to prevent overcharging, but a wary public complained about reliability and a large percentage of the automobile manufacturers offered a straight 3rd brush design. Regulators The Model T Ford used an 18 Volt magneto for powering the engine. Henry Ford used this magneto to power the Model T lights. With no battery, the lights provided “good” light at 8 MPH and “Full

Candle Power” at 12 MPH. [52]

Many owners added a 6 volt battery with a switch to cut the lights

in, but with no generator, it required an external battery charger. After the 12,225,528th Model T ,

Ford finally added a generator. The generator introduced to the Model T was the 3rd brush type, and it was manufactured by Ford until 1927. It is the same as the “Power House” generator on the earliest Model A. There was no external regulation using this generator, but a electro-magnetic cutout was used to connect the battery to the generator above speeds of 10 MPH. The Model T continued to use the magneto spark until its demise in 1927. The Model T and Model A 3rd brush generator design was used at Ford until after 1935. In 1935 Ford added a two step regulator to the 3rd brush generator to eliminate the battery overcharging problem. The two step voltage regulator was followed by a two pole generator, with a combined cutout and voltage regulator, and finally a three coil unit combining the cutout, a voltage regulator, and a current regulator. This combination continued until Ford finally abandoned the old fashioned electro-magnet relay regulators in favor of the solid state regulator in 1969. Alternators Generators with electro-magnetic relay regulators continued to be used by all manufacturers until the advent of the alternator. The first practical alternator was developed by the Leese-Nevill company in

1952 and called the “Rectified Alternating Current Generating System”. [53]

Eventually this name was shortened to “ alternator“. Leese-Nevill developed both 6 volt and 12 volt designs. The “big three” were not impressed at first and it was 8 years before Chrysler introduced an alternator on the Dodge Valiant in 1960, then on the Chrysler Imperial and Plymouth in 1961. By 1964 the alternator’s benefits of operating at stop and go driving was recognized, and by 1969 they were in wide spread usage. Ford began using the Leese-Nevell alternator in 1965 in combination with the

older electro-magnetic regulators, finally changing over to solid state regulation in 1968. [54]

. Eventually, Ford settled on the Auto Lite alternator. Alternators finally transitioned to their current form in 1969 with the addition of the Zener Diode and the integral regulator.

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Foot Notes:

[1] Dykes Automobile Encyclopedia, fifteenth edition 1929; A.L. Dyke at page 325

[2] Interestingly, the Model T utilized a negative ground. See Dykes Automobile Encyclopedia at page 1124

.

[3] The storage battery on the Ford Model T was the same specifications according to Dyke’s Instruction #85 at page

1123. The Model T used the “Power House” generator and had the 3rd brush current limiter. [4]

Other auto manufacturers used Exide, Prest-O-Lite, Willard, and USL as shown in Dykes Automobile Encyclopedia, 1929 at page 1057 [5]

Of course this is not “capacity”

[6] Les Andrews; Model A Mechanics Handbook;, at page 1-19

[7] Various Model A parts supplier catalogs; Macs Auto Parts 2006 Catalog at page 122 for example

[8] Jim Schild, Restorer’s Model A Shop Manual; at page 157

[9] Les Andrews, Model A Ford Troubleshooting and Diagnostics at page 2-3

[10] Les Andrews, Model A Ford Mechanics Handbook, Battery Efficiency at page 1-19

[11] Meaning a new or nearly new battery

[12] These observations, while based on engineering data, are subject to variation and are not to be taken as absolute

performance, since the starting requirements of individual cars depend on many factors. It is likely, that an individual car may exhibit better or worse performance than this “nominal” estimated starter motor performance versus temperature. [13]

Jim Schild; Restorer’s Model A Shop Manual, at page 144

[14] W. Peukert, Über die Abhängigkeit der Kapacität von der Entladestromstärcke bei Bleiakkumulatoren,

Elektrotechnische Zeitschrift 20 (1897) [15]

Jim Schild, Restorer’s Model A Shop Manual at page 144

[16] The Model “A” Instruction Book, 1931 at page 25

[17] The Peukert constant for an “ideal battery” is 1 , however real batteries have Peukert constants ranging from 1.3 for

lead acid batteries to even higher. The Peukert constant for lead acid batteries will go up as the battery ages. [18]

The Model A Instruction Book, Ford Motor Company, at page 25

[19] Les Andrews, The Model A Mechanics Handbook

[20] Jim Schild, Shop Manual

[21] The Model A Ford Instruction Book at page 29.

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[22] Model A Service Bulletins Complete; Lincoln Publishing 2003; These are reprints of original Bulletin folio’s

which were distributed to Ford Dealers. [23]

The Ford Service Bulletin at page 209

[24] Jim Schild, Restorers Model A Shop Manual at page 148

[25] Victor Page; The Construction, Operation, and Repair of the Model A Ford; Lincoln Publishing 1931; at page

319. [26]

Ibid at page 349

[27] Les Andrews; The Model A Mechanics Handbook at page 1-193

[28] This is valid only if the cutout is the stock relay type. If the cutout is a diode type or a voltage regulator type, the

battery charge current will be applied to the battery. [29]

Depending on whether you have one or two tail lights.

[30] For example, if you have halogen bulb headlights

[31] Or a Diode type cutout

[32] Ford Motor Company; The Model A Instruction Book, at page 29

[33] Les Andrews; Model A Ford Mechanics Handbook Volume II at page 4-10

[34] The battery in my Model A, built by Ramcar Industries, has no capacity values stated on it

[35] Les Andrews, Model A Ford Mechanics Handbook Vol. II, at page 4-13

[36] Much of this information is from Automotive Electrical Systems, Irving Frazee and Earl Bedell, the American

Techincal Society; published in 1952 [37]

If you are making this test with a more modern car which the starter switch energizes the starter control circuit, remove the coil wire at the distributor and ground it to the block. This will prevent damage to the coil, and will prevent the car from starting. [38]

Conversation with Jerry Robinette

[39] This assumes that you have good connections however.

[40] It does not mean that below 10 mph the generator will charge the battery, since if a stock cutout is used, the cutout

will still disconnect the charging system from the battery. [41]

Automobile Ignition, Starting and Lighting; Charles Haward, 1922 at page 735 - 741

[42] The Dodge Brothers Automobile Company was sold to Chrysler in 1926 and the last of these cars were converted

to 6 Volts and the 3rd brush setting was to be 14 Amps. [43]

Gasoline Automobiles, James Moyer; 1926 at page 244

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[44] Unless the owner of a restored Model A has added a voltage regulator

[45] Assuming that few accessories or lights are turned on

[46] In then year dollars

[47] Also Grey-Davis at 6 Volts

[48] Dykes Automotive Encyclopedia, A.L. Dyke; published 1929 at page 1139B

[49] Automobile Ignition and Lighting 1922; Charles Haward, American Technical Society. pages 735 - 741

[50] Dykes Automobile Encyclopedia, A.L. Dyke 1929 at page 1123

[51] Glenn’s Auto Repair Manual (Chilton’s), Harold Glenn, 1962 at page 934

[52] Dykes Automobile Encylopedia at page 1119

[53] Auto Mechanics Fundamentals, Martin Stockel, 1969 at page 391

[54] Chilton’s 1972

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Battery Application Knowledge Basics

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