Unit 13

Batteries and Other Electrical Sources

Battery History

• Luigi Galvani in 1791 first noticed

indications of electricity while

experimenting with frog legs.

• Alessandro Volta in 1800 created the first

practical battery.

• Batteries are composed of one or more

cells.

Unit 13

Batteries and Other Electrical Sources

Typical cell and battery schematic symbols.

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Batteries and Other Electrical Sources

Simple potato voltaic cell.

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Batteries and Other Electrical Sources

Simple nickel/paper/penny voltaic cell.

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Batteries and Other Electrical Sources

Voltaic Cells

• The individual cell voltage is determined by

the construction materials.

• The electromotive series of metals ranks

how easily they give up electrons.

• A primary cell cannot be recharged.

• A secondary cell can be recharged.

Unit 13

Batteries and Other Electrical Sources

Electromotive series of metals list.

Unit 13

Batteries and Other Electrical Sources

Voltaic Cells

• The amount of current a cell can deliver is

determined by the surface area of its

plates.

• The current capacity is the amount of

power a cell can deliver.

• Primary cells are rated in milliampere

hours.

Unit 13

Batteries and Other Electrical Sources

Voltaic cells.

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Batteries and Other Electrical Sources

Carbon-zinc cell.

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Batteries and Other Electrical Sources

Mercury button cell.

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Batteries and Other Electrical Sources

Nickel-Metal Hydride Cells (Ni-MH)

• This type of cell is similar to nickel-

cadmium cells.

• Both types of cells have 1.2 volts per cell.

• Both types of cells have similar

charge/discharge curves.

Unit 13

Batteries and Other Electrical Sources

Nickel-Metal Hydride Cells (Ni-MH)

• Nickel-metal hydride cells have 40%

higher energy density.

• Ni-MH cells are more environmentally

friendly.

• Ni-MH cells are replacing nickel-cadmium

cells.

Unit 13

Batteries and Other Electrical Sources

Lithium-Ion Cells

• Lithium-ion cells can be recharged and

have a very high energy density for their

size and weight. The weight energy density

is three times greater than nickel-cadmium

cells.

• They have a voltage of 3.6 volts per cell.

Unit 13

Batteries and Other Electrical Sources

Power comparison based on size.

Unit 13

Batteries and Other Electrical Sources

Power comparison based on type.

Unit 13

Batteries and Other Electrical Sources

Batteries

• Batteries have internal resistance that affects

their performance.

• Series-connected batteries add their voltages

while their current remains constant.

• Parallel-connected batteries add their

currents while their voltage remains constant.

• Never parallel connect batteries of different

voltages.

Unit 13

Batteries and Other Electrical Sources

Series-connected batteries.

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Batteries and Other Electrical Sources

Parallel-connected batteries.

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Batteries and Other Electrical Sources

Combination-connected batteries.

Unit 13

Batteries and Other Electrical Sources

Solar Cells

• Solar cells use the principle of photon

energy striking a semiconductor material to

produce electricity.

• Silicon solar cells produce an open circuit

voltage of .5 volts in direct sunlight.

Unit 13

Batteries and Other Electrical Sources

Solar cell schematic symbol.

Unit 13

Batteries and Other Electrical Sources

Photovoltaic circuit.

Unit 13

Batteries and Other Electrical Sources

Thermocouples

• A thermocouple is a junction of two

dissimilar metals that produce a voltage

when heated.

• A thermopile is a series-connected

assembly of thermocouples used to

increase voltage output.

Unit 13

Batteries and Other Electrical Sources

Thermocouple.

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Batteries and Other Electrical Sources

Thermopile.

Unit 13

Batteries and Other Electrical Sources

A safety system using a thermocouple.

Unit 13

Batteries and Other Electrical Sources

Piezoelectricity

• Piezo is derived from the Greek word for

pressure.

• Piezoelectricity is produced by some

materials when placed under pressure.

• The pressure can be caused by

compression, twisting, bending, or

stretching.

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Batteries and Other Electrical Sources

Piezoelectric effect.

Unit 13

Batteries and Other Electrical Sources

Practical Application 1• Your job is to order and connect lead-acid cells

used to supply a UPS (Uninterruptible Power

Supply).

• The battery output voltage must be 126 volts

and have a current capacity of not less than

250 ampere-hours.

• Each cell has a rating of 2 volts and 100

ampere-hours. How many cells are required?

Unit 13

Batteries and Other Electrical Sources

Practical Application 2

• Your job is to replace a bank of nicad cells used

to supply emergency lighting with a bank of

lead-acid cells.

• There are 100 cells in the original nicad bank.

Each cell has a 120 ampere-hour rating.

• The lead-acid cells each have a 60 ampere-

hour rating.

• How many cells are required?