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.
Unit 13
Batteries and Other Electrical Sources
Simple potato voltaic cell.
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Batteries and Other Electrical Sources
Simple nickel/paper/penny voltaic cell.
Unit 13
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 nickelcadmium 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.
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Batteries and Other Electrical Sources
Power comparison based on type.
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Batteries and Other Electrical Sources
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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.
Unit 13
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.
Unit 13
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
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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 amperehour rating.
How many cells are required?