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Battery Monitoring –Why Technology MattersMats KarlstromV.P. Sales & Marketing, Alber

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Agenda• Introduction• Why is battery monitoring needed?

– Example of battery failure

• Why are resistance measurements important?• Doing it right

– Why Alber’s resistance measurement technology will help customers while others fail

• Monitoring advantages– Optimizing useful battery life– Reliable test data– Safety

• Alber products and their application

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Who is Alber?

Established 1972

Based in Boca Raton Florida

We manufacture battery test equipment based on extensive experience in and knowledge about Battery design and

Battery aging characteristics.

We are the Battery Test Experts!

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Capacity vs. Resistance Test What’s the difference?

Battery Capacity Testing. Off-line discharge test using load bank with constant current capability while continuously monitoring each individual battery cell voltage to identify the bad cells. – Time consuming (1 to 10 hours plus re-charge time)– Requires external load bank and sometimes backup battery+ Reliable. Only way to truly assess the battery’s absolute capacity

Resistance Test.On-line test measuring the internal resistance of each battery cell. As battery condition declines, the resistance increases. Increased internal resistance indicates aging or pre-mature failure before the cell cause critical failure to the battery+ On-line, non-invasive test that can be performed manually or

automatically- Does not provide an absolute capacity value and chemical problems are

more difficult to detect in an early stage.

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What do we learn from this example?• Increased resistance revealed the weakest link

– ~ 25% increased resistance in one module is enough to fail a complete battery string

• Monitoring overall voltage is not enough• Monitoring cell voltage will not detect a bad cell• Partial discharge tests will not detect all faults• Individual cell voltage monitoring is important

during discharge tests• This is why it is important to DO IT RIGHT!

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Why monitor?

Because Batteries Fail!Batteries are like humans. Sooner or later the battery will reach end of life. It can happen through…

• “Normal” aging– Positive Grid Corrosion

• Pre-mature failure– Manufacturing defects– Battery “abuse”– High temperature – Excessive charge current– Defective chargers– Damaged battery jars

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Cell Resistance

Capacity

Resistance

25% increased resistance

80% capacity

Safety zone

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Internal resistance

Why is internal resistance related to battery capacity?

New Grid

Positive plate

Negative plate

Separator material

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Internal resistanceLead Paste Grid Structure

Fully Charged During Discharge

CorrosionCracks

Aged Plate

Active Material

Expanding

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Internal resistance

New Grid Aged Grid

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Ohmic measurements• The following terms are used, in the battery industry, to

describe internal ohmic measurements :

• AC Impedance (Z) (B-tech, MEGGER, Polytronics, Enersafe…)

• AC Conductance (Siemens) (Midtronic)

• Resistance (NDSL/Cellwatch)

• DC Resistance (Alber)

But this is only the presentation of the data.It is the way the measurement is made that

dictates the accuracy and bearing of the test

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Metallic Resistance

Capacitor

Obtained from Johnson Control application note

Electro Chemical Resistance

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Why is internal ohmic measurements tricky?

~ 40 % of resistance is in parallel with a capacitor

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Normal battery operation

When load is applied, DC current is generated

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AC testing

AC testing is an abnormal battery condition. When AC load is applied, most of the current will pass through the capacitor. Test frequency and size of

capacitor will define the amount of current passing through the capacitor instead of plates.

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Voltage

Current

Open Circuit Voltage

Rint = IV1

ΩV

How are Alber resistancemeasurements made?

Test current is disconnected before the battery voltage reaches the open circuit voltage level.

No electro chemical reaction and no loss of capacity.

V2 -

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Normal Operation

Aged Condition

AC Testing

Alber Test Method

Non-Technical Explanation

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Test Current• The resistance difference between

a good and bad battery is 25%• Example:

A 1000Ah battery has 200µΩresistance. 25% = 50µΩ

• In order to accurately measure this difference the resolution of the test equipment should be 10% of the critical value

New Battery 200µΩ

Difference between good and bad 50µΩ

Required resolution

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Test Current/ Measurement Resolution

• Ohms law: R = V/I• 50µΩ difference from previous example.

• 1A test current requires 5µV resolution• 10A test current requires 50µV resolution• 30A test current requires 150µV resolution • Most competitors use test currents below 1A.

Alber use a 30A resistive load!

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Noise

Low AC test signal will “disappear” in UPS noise, Trending data will typically change when noise

change due to load or failing capacitors on UPS.The Alber DC test method is not affected by ripple

Typical ripple 40mV (40.000µV)

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Trending difference between AC and DC

25% increase (~70% - 90% capacity)

DC resistance Time

50 % increase (~25% - 50% capacity)

No LoadNo ripple

Partial LoadSome ripple

Nominal LoadConsiderable ripple

AC based readings, (Impedance)Continuous variations due to noise

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Trending difference between AC and DC

Screen dump from AC based trend report

Mondays

Discharge April 4 th

True DC resistance?

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Doing it right• Alber’s technology is developed based on

– experience and knowledge about how batteries fail

– Always comparing capacity tests with resistance tests

• Alber’s technology addresses the three most important battery testing obstacles – The capacitor effect– The noise problem– Resolution requirements

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• We have to detect problems in the complete conduction path– Internal to the cells (to secure capacity)– Inter-cell and Inter-tier connections

Increased resistance = Increased temperature = Increased resistance = Increased temperature … Catastrophic failure

What is needed to make sure that current can be supplied to the critical load?

Increase Reliability

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Modular approach?

?

?

?

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Cost savingsOptimize battery life• Monitor critical parameters and take appropriate action

– Internal resistance• Replace bad cells before they affect other cells• Maintain a balanced resistance level in all redundant strings

– Temperature• Temperature has a direct influence on battery life• Uneven temperature over the string cause cells to float

differently

– Voltage • Charge voltage should be adjusted to ambient temperature

– Float current• Improper ripple affects the battery life

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FLOODED IEEE 450 VRLA IEEE 1188 Recommended Task

Monthly Quarterly Annually Monthly Quarterly Bi-Annually Annually Battery system voltage X X

Charger current and voltage

X X

Ambient temperature X X Visual inspection X X Electrolyte levels X

Pilot cell voltage and specific gravity

X

Specific gravity all cells X All cell voltages X X

All cell temperatures X 10% Only

X

Cell internal ohmic values

X X

Intercell connection resistance

X X UPS X

Detailed internal visual inspection

X

AC ripple current and voltage

X X

Capacity test 5 Years X

IEEE 450 / 1188 Task Matrix

Can be monitored Equivalent data provided

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Man-hour savings vs. IEEE based service contract

$1,280 4$320

4 Hours @ $80/hr

(test time, travel, test

report)

Substation1 string of

60 cells

$2880 2$1440 $6 per cell UPS

2 Strings of240 cells

$9,6004$2,400$15 per module

UPS4 Strings of forty 12V modules

Test savings per year

No of visits per year

Cost per routine testCost basis

Batteryapplication.

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Safety

Detect problems beforebefore they cause a catastrophic system failure!system failure!

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Why Alber?• Repeatable readings

– Test result shows actual battery condition• Correlates with Capacity tests

– Takes the “capacitor effect” out of play• Tests the complete conduction path

– All cells and connections are included in test results– Separate sense leads for Inter-tier connections

• Monitors all critical parameters– Monitors voltage real time during discharge

• Easy to interpret test results• Can work stand alone without PC • Well proven in all standby battery applications

– Intel, Nasdaq, Verizon, BankOne, Visa, Sun Micro system, HP, UPS…

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Battery Monitors

BDS-256 Battery Diagnostic System

Monitor any battery system up to 600 volts DC

• UPS systems

• Generating stations

• Industrial

UL Certified

CE Approved

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BDS Controller

• Collects and stores data from the DCMs

• Microprocessor driven

• Stand alone – No on site PC required.

• 8 strings of 256 cells per Controller

The “Brain” that control the system.

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Data Collection Module (DCM)

• 48 cells or modules • 2 temperatures• Discharge current• Charger float current

The Data Collection Module acquires all readings from the battery

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External Load Module

• One ELM for each string

• Tests battery in 10% increments

• Test current approximately 30 amps

Supports proactive DC internal resistance testing

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Configuration examples 2 strings, 240 jars, 2V per jar

1 controller String 1

String 2

5 DCM’s and1 ELM per string

Fiber optics for data transfer and 24VAC power supply between DCM and Controller

1 CT and at least 2 temperature probes per string

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Configuration examples 3 strings, 120 jars, 4V per jar

1 controller String 1

String 3

3 DCM and 1 ELM per string

String 2

1 CT and at least 2 temperature probes per string

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Configuration examples 1 strings, 240, 2V jars

1 strings, 120, 4V jars

1 controller String 1

String 2

5 DCM’s and1 ELM per string

Fiber optics for data transfer and 24VAC power supply between DCM and Controller

1 CT and at least 2 temperature probes per string

1 CT and at least 2 temperature probes per string

3 DCM’s and 1 ELM per string

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Parameters Monitored• Overall voltage• Discharge current• Charger float current (optional)• 2v cells, NiCad cells, 4v, 6v, 8v and 12v modules• Temperature• Resistance of all cell/jars, inter-cells, and inter-

tiers

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System Level I/O

• System inputs–Remote alarm reset–16 digital inputs

• System outputs (form C contacts)–Maintenance alarm–Critical alarm–8 programmable control outputs(BDS-

256)

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Communication

• Two RS-232 for local computer

• RJ-11 for telco dial up

• RJ-45 for Ethernet connection

• Standard Modbus protocol

• OPC Compliant

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The NEW optimized UPS cabinet monitor

The BDS-40 Battery Cabinet Monitor

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Designed for battery cabinetsOptimized monitor• All-in-one enclosure• Pre-manufactured cables• Tests the complete conduction path

– Individual leads for inter-tier

• Easy install and setup– Setup Wizard

• Built-in decision support– Identifies issues and suggests corrective

maintenance procedure

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BDS-40• BDS-40 Base unit• All-in-one controller, Data Collection Module and

Load Module• One per system. Can power up 5 Plus units• 2 temperatures, 1 current transducer / string• Customized harness for easy install• Simplified setup• 4 U high, 16” deep, 19” wide to be mounted on top

of cabinet

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BDS-40• BDS-40 Plus unit• All-in-one Data Collection Module and Load Module• Connects to Base unit via fiber optic cable• One unit for cabinets 2-6• 2 temperatures, 1 current transducer • Customized harness for easy install• Simplified setup• 3 U high, 16” deep, 19” wide to be mounted on top

of cabinet

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BEFORE

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AFTER

BDS-40Base Unit

BDS-40Plus Units

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Monitoring via Web-browser

Executive summaryand detailed reports

Pop-up screens with real time data

Real time string status

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Email alert

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Decision support reporting

• Automatic data analysis with explanations of abnormal data

• Suggests appropriate maintenance activities

• Zip & sends test data for expert analysis

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MPM-100

• Designed for applications below 130VDC

• UL and CE approved• More than 100 battery

configurations available• Monitors 1 string of

120VDC or up to 4 strings of 12, 24 or 48VDC

• Modbus protocol• Powered from DC bus or

115VAC• Network, Serial, Modem

connection options

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Alberthe total solution