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Glossary of Common Battery Terms |
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Battery
a device that converts energy, by chemical reaction or physical
reaction, into electric current.
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Primary Battery
energy is exhausted when active materials are consumed (carbon-zinc
dry cell, lithium battery, silver oxide battery, alkaline battery)
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Secondary Battery
active materials are regenerated by charging (nickel cadmium
(NiCd), nickel metal hydride (NiMH), Lithium Ion, Lithium Polymer,
Sealed Lead Acid.
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Series Connection
Connection of a group of battery cells by sequentially interconnecting
the terminals of opposite polarity thereby increasing the voltage
of the battery group but not increasing capacity (i.e. positive
to negative connections).
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Parallel Connection
Connection of a group of batter cells by interconnecting all
terminals of the same polarity, thereby increasing the capacity
of the battery group but not increasing the voltage (i.e. positive
to positive and negative to negative).
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Cadmium
Chemical symbol Cd. This metallic element is the chemically
active material of a nickel cadmium battery's negative electrode.
When the battery is charged, the negative electrode surface
consists of cadmium. As the battery discharges, the cadmium
progressively changes into cadmium hydroxide (Cd (OH2)).
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Cadmium Hydroxide
Active material used at the negative electrode of the Nickel-Cadmium
Cell.
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Metal Hydride
A general name for chemical compounds consisting of metal elements
and hydrogen.
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Nickel Hydroxide
The active material in the positive electrode of NiMH and NiCd
batteries.
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Nickel Oxyhydroxide
The chemical name of NiOOH. Indicates that oxidation of Ni (OH)2
has progressed, and that the active material of the positive
electrode of an NiCd or NiMH battery is charged.
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Capacity
The quantity of electricity that can be obtained from a battery
in one cycle from full charge to full discharge when the battery
is discharged under conditions of rated current level and ambient
temperature within the predetermined range. Generally, capacity
is expressed in units of mAh (milliampere-hour).
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Nominal Capacity
The standard capacity designated by a battery manufacturer to
identify a particular cell model
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Nominal Voltage
The standard voltage used to express the capacity of a particular
battery model It is generally equal to its electromotive force
or its approximate voltage during normal operation. Typical
Values:
- 1.2 volts per cell for NiCd and NiMH
- 3.6 or 3.7 volts per cell for Lithium Ion or Lithium Polymer
- 3 volts per cell for lithium primary
- 2 volts per cell for sealed lead acid
- 1.5 volts per cell for alkaline and carbon zinc
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Discharge Rate
The discharge rate is the rate at which current is removed from
a battery. When a battery is discharged at a current level "i",
for a period until the end discharge voltage is '"h",
the discharge is referred to as the h-hour rate discharge, while
"i" is known as the h-hour rate discharge current.
For practical use, nominal capacity is used as standard.
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End-Voltage
The voltage that indicates the end limit of discharge. This
voltage is almost equivalent to limitation of practical use.
Typical values:
- 1.0 volt per cell for NiCd and NiMH
- 1.75 volts per cell for sealed lead acid
- 2.75 volts per cell for lithium ion and lithium polymer
- 2.0 volts per cell for primary lithium
- 0.9 volts per cell for alkaline and carbon zinc
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Open circuit voltage
The voltage between terminals of a battery without any load.
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Operating voltage
The voltage between terminals when a battery is subjected to
a load. Usually expressed by the voltage of the battery at 50%
discharge point.
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Polarity Reversal
Reversing of polarity of the terminals of a small-capacity cell
in a multi-cell battery due to overdischarge.
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Positive Electrode
The electrode which has a positive potential. Electric current
from this electrode flows in the external circuit during discharge.
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Negative Electrode
The plate which has an electrical potential lower than that
of the other plate during normal cell operation. Electric current
from the external circuit flows into the cell at the negative
electrode during discharge. Also called minus electrode.
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Self-Discharge
a decrease in battery capacity which occurs without any current
flow to an external circuit. Typical values:
- 1% per day for NiCd
- 2% per day for NiMH
- ~0% per day for Lithium Ion and Lithium Polymer
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Short Circuit
Directly connecting the positive electrode (terminal) to the
negative electrode (terminal) of the battery.
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Thermistor
A circuit element with a negative temperature coefficient. It
is built into batteries and used to detect ambient temperature
or battery temperature. A battery charger may use this device
to properly charge a battery.
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