| AB5 |
A metal alloy (e.g., LaNi5)
capable of undergoing a reversible hydrogen absorption/desorption
reaction as the battery is charged and discharged, respectively. |
| Absorption |
The taking up or retention
of one material by another by chemical or molecular action. |
| Alloy |
A mixture of several other
metals or a metal and a non-metal. |
| Ambient
Humidity |
The average humidity of
the surroundings. |
| Ambient
Temperature |
The average temperature
of the surroundings. |
| Ampere-Hour
Capacity |
The quantity of electricity
measured in ampere-hours (Ah) which may be delivered by
a cell or battery under specified conditions. |
| Anode |
The electrode in an electrochemical
cell where oxidation takes place. During discharge, the
negative electrode of the cell is the anode. During charge,
the positive electrode is the anode. |
| Battery
or Pack |
Two or more electrochemical
cells electrically interconnected in an appropriate series/parallel
arrangement to provide the required operating voltage
and current levels. Under common usage, the term "battery"
is often also applied to a single cell. |
| Bobbin |
A cylindrical cell design
utilizing an internal cylindrical electrode, and an external
electrode arranged as a sleeve inside the cell container. |
| C-Rate
(also see Hourly Rate) |
Discharge or charge current,
in amperes, expressed in multiples of the rated capacity.
For example, C/10 discharge current for a battery rated
at 1.5 Ah is:
1.5 Ah/10 = 150 mA (A cell's capacity is not the same
at all discharge rates and usually increases with decreasing
rate.) |
| Capacity |
The total number of ampere-hours
or watt-hours that can be withdrawn from a fully charged
cell or battery under specified conditions of discharge. |
| Capacity
Retention (or Charge Retention) |
The fraction of the full
capacity available from a battery under specified conditions
of discharge after it has been stored for a period of
time. |
| Cathode |
The electrode in an electrochemical
cell where reduction takes place. During discharge, the
positive electrode of the cell is the cathode. During
charge in a rechargeable battery, the negative electrode
is the cathode. |
| Cell
|
The basic electrochemical
unit used to generate or store electrical energy. |
| Charge
|
The conversion of electrical
energy, provided in the form of electrical current from
an external source, to restore the chemical energy in
a cell or battery. |
| Charge
Control |
Technique for effectively
terminating the charging of a rechargeable battery. |
| Closed-Circuit
Voltage (CCV) |
The potential or voltage
of a battery when it is discharging or charging. |
| Constant
Current Discharge |
A battery discharge regime
whereby the current drawn during the discharge remains
constant. |
| Constant
Power Discharge |
A battery discharge regime
whereby the current during the discharge increases as
the battery voltage decreases. |
| Constant
Resistance Discharge |
A battery discharge regime
whereby the resistance of the equipment load remains constant
throughout discharge. |
| Continuous
Test |
A test in which a battery
is discharged to a prescribed end point voltage without
interruption. |
| Coulomb |
The amount of electricity
transported by a current of one ampere flowing for one
second. |
| Current
Collector |
An inert structure of high
electrical conductivity used to conduct current from or
to an electrode during discharge or charge. |
| Current
Density |
The current per unit active
area of the surface of an electrode. |
| Current
Drain |
The current withdrawn from
a battery during discharge. |
| Cutoff
Voltage (also see End Voltage) |
The battery voltage at
which the discharge is terminated. The cutoff voltage
is specified by the battery manufacturer and is generally
a function of discharge rate. |
| Cycle
Life |
The number of cycles under
specified conditions which are available from a secondary
battery before it fails to meet specified criteria as
to performance. |
| Depth
of Discharge |
The ratio of the quantity
of electricity (usually in ampere-hours) removed from
a battery to its rated capacity. |
| Desorption |
The opposite of absorption,
whereby the material retained by a medium or another material
is released. |
| Discharge |
The conversion of the chemical
energy of a battery into electrical energy, and the withdrawal
of the electrical energy into a load. |
| Discharge
Rate |
The rate, usually expressed
in amperes, at which electrical current is taken from
the battery. |
| Drain |
The current withdrawn from
a battery during discharge. |
| Dry
Cell |
A cell with immobilized
electrolyte. The term "dry cell" is often used
to describe the Leclanche cell. |
| Duty
Cycle |
The operating regime of
a battery including factors such as charge and discharge
rates, depth of discharge, cycle duration, and length
of time in the standby mode. |
| E-Rate |
Discharge or charge power,
in watts, expressed as a multiple of the rated capacity
of a cell or battery which is expressed in watt-hours.
For example, the E/10 rate for a cell or battery rated
at 17.3 watt-hours is 1.73 watts. (This is similar to
the method for calculating C-Rate.) |
| Electrochemical
Equivalent |
Weight of a substance that
is deposited at an electrode when the quantity of electricity
which is passed is one coulomb. |
| Electrode |
The site, area or location
at which electrochemical processes take place. |
| Electrolyte |
The medium which provides
the ion transport mechanism between the positive and negative
electrodes of a cell. |
| End
Voltage (also see Cutoff Voltage) |
The prescribed voltage
at which the discharge (or charge, if end-of-charge voltage)
of a battery may be considered complete. |
| Energy |
The output capability of
a cell or battery, usually expressed in watt-hours. |
| Energy
Density |
The ratio of the energy
available from a battery to its volume (Wh/L) or weight
(Wh/kg). |
| Forced
Discharge |
Discharging a cell in a
battery, by the other cells or an external power source,
below zero volts into voltage reversal. |
| Fuse |
Device used for cutting
off an electrical current in the event of an abusive condition. |
| Gassing |
The evolution of gas from
one or more of the electrodes in a cell. Gassing commonly
results from local action (self-discharge) or from the
electrolysis of water in the electrolyte during charging. |
| Gravimetric
Energy Density |
The ratio of the energy
output of a cell or battery to its weight (Wh/kg). This
term is used interchangeably with specific energy. |
| Hazardous
Waste |
Waste which is classified
as "hazardous" (i.e., potentially harmful to
the environment) by the government. |
| Hertz |
The standard unit of frequency.
A frequency of one complete cycle per second is a frequency
of one hertz. |
| Hourly
Rate (also see C-Rate) |
A discharge rate, in amperes,
of a battery which will deliver the specified hours of
service to a given cutoff voltage. |
| Intermittent
Test |
A test during which a battery
is subjected to alternate periods of discharge and rest
according to a specified discharge regime. |
| Internal
Impedance |
The opposition exhibited
by a circuit element (cell or battery) to the flow of
an alternating current (a.c.) of a particular frequency
as a result of resistance, induction and capacitance. |
| Internal
Resistance (IR) |
The opposition exhibited
by a circuit element to the flow of direct current (d.c.).
In a cell, the internal resistance is the sum of the ionic
and electronic resistances of the cell components. |
| IR
Drop |
A voltage drop associated
with the electrical resistance (R) of a battery or current
flow (I). The voltage drop is the product of the current
(in amperes) and the resistance (in ohms). |
| Limiting
Current |
The maximum current drain
under which the particular battery will perform adequately
under a continuous drain. The rate is based on whatever
drain rate reduces the running voltage to 1.1 volts. |
| Memory
Effect |
A phenomenon in which a
cell or battery operated in successive cycles to the same,
but less than full, depth of discharge temporarily loses
the rest of its capacity at normal voltage levels. |
| Metal
Hydride |
An intermetallic compound
or alloy in which hydrogen has been absorbed; also, the
negative electrode in a nickel-metal hydride battery. |
| Midpoint
Voltage |
The voltage of a battery
midway in the discharge between the start of the discharge
and the end voltage. |
| Nominal
Voltage |
The characteristic operating
voltage or rated voltage of a battery. |
| Open-Circuit
Voltage (OCV) |
The difference in potential
between the terminals of a cell when the circuit is open
(no-load condition). |
| Overcharge |
The forcing of current
through a cell after all the active material has been
converted to the charged state, that is, continued charging
after reaching 100 percent state-of-charge. |
| Overdischarge |
The process of discharging
a cell or battery beyond its cutoff voltage and possibly
into voltage reversal. |
| Parallel |
Term used to describe the
interconnection of cells or batteries in which all the
like terminals are connected together. Results in increased
capacity. |
| Passivation |
The phenomenon by which
a metal, although in conditions of thermodynamic instability,
remains indefinitely unattacked because of modified or
altered surface conditions. |
| Polarity |
In electricity, the condition
of being positive or negative. |
| Polarization |
The lowering of the potential
of a cell or electrode from its equilibrium value caused
by the passage of an electric current. |
| Positive
Temperature Coefficient (PTC) |
A thermally reactive device
which becomes highly resistive at a specific temperature
or current. |
| Primary
Battery |
A battery which is not
intended to be recharged and is discarded when the battery
has delivered all of its electrical energy. |
| Pulse
Current |
A periodic current drain
of higher than normal drain rates. |
| Rated
Capacity |
The number of ampere-hours
a battery can deliver under specific conditions (e.g.,
rate of discharge, end voltage, temperature); usually
specified by the battery manufacturer. |
| Rechargeable
(or "Secondary") Battery |
A galvanic battery which,
after discharge, may be restored to the fully charged
state by the passage of an electrical current through
the cell in the opposite direction to that of discharge. |
| Reversal |
The changing of the normal
polarity of a battery due to overdischarge. |
| Safety
Vent |
A venting mechanism designed
into a cell which activates under specific conditions
of abuse to relieve internal pressure. |
| Secure
Waste Landfill |
A landfill designed for
disposal of normal household trash but which meets government
standards designed to protect the environment. |
| Self-Discharge |
The loss of useful capacity
of a battery on storage due to internal chemical action
(local action). |
| Separator |
An ionic permeable electronically
nonconductive spacer or material which prevents electronic
contact between electrodes of opposite polarity in the
same cell. |
| Series |
The interconnection of
cells in such a manner that the positive terminal of the
first is connected to the negative terminal of the second,
and so on, resulting in increased voltage. |
| Service
Life |
The period of useful life
of a battery before a predetermined end-point voltage
is reached. |
| Shelf
Life |
The duration of storage
under specified conditions at the end of which the battery
still retains the ability to give a specified performance. |
| Short-Circuit
Current (SCC) |
The initial value of the
current obtained from a battery in a circuit of negligible
resistance. |
| Specific
Energy |
The ratio of the energy
output of a cell or battery to its weight (Wh/kg). This
term is used interchangeably with gravimetric energy density. |
| Spiral
Wound |
An electrode structure
of high surface area created by winding the electrodes
and separator into a spiral-wound, jelly-roll configuration. |
| Temperature
Cutoff (TCO) |
A protective or safety
device (e.g., thermostat, PTC, etc.) which senses temperature
(e.g., in a battery) and opens or cuts off the electrical
circuit if the specified temperature is exceeded, thus
preventing a further rise in temperature due to the charge
or discharge of a battery. |
| Thermistor |
A temperature sensitive
resistor, usually made from specially processed oxides. |
| Thermostat |
A temperature sensitive
switch. |
| Top-Up
Charge |
A low rate charge following
the main charge, designed to ensure maximum capacity. |
| Trickle
Charge |
A charge at a low rate,
balancing losses through local action and/or periodic
discharge, to maintain a cell or battery in a fully charged
condition. |
| Voltage
Depression |
An abnormal drop in voltage
below expected values during the discharge of a battery. |
| Voltage
Delay |
Time delay for a battery
to deliver the required operating voltage after it is
placed under load. |
| Voltage-Keyed |
A system which incorporates
a mechanical identifier on batteries and devices to ensure
only batteries of the correct voltage are connected to
the device. |
| Voltage
Reversal |
The changing of the normal
polarity of a battery due to overdischarge. |
| Volumetric
Energy Density |
The ratio of the energy
output of a cell or battery to its volume (Wh/L). |
| Wall-less
Design |
A battery design where
the structural support for the cells is formed by an open
plastic framework. |
| Working
Voltage |
The typical voltage or
range of voltage of a battery during discharge (also called
operating voltage or running voltage). |
