Accumulator - A rechargeable battery or cell.

Ampere or Amp - An Ampere or an Amp is a unit of measurement for an
electrical current. One amp is the amount of current produced by an
electromotive force of one volt acting through the resistance of one ohm.
Named for the French physicist Andre Marie Ampere. The abbreviation for Amp is
A but its mathematical symbol is "I". Small currents are measured in
milli-Amps or thousandths of an Amp.

Amp Hour or Ampere-Hour - A unit of measurement of a battery's
electrical storage capacity. Current multiplied by time in hours equals
ampere-hours. One amp hour is equal to a current of one ampere flowing for one hour. Also, 1 amp hour is equal to 1,000 mAh

Ampere-Hour Capacity - The number of ampere-hours which can be
delivered by a battery on a single discharge.

Anode - During discharge, the negative electrode of the cell is the
anode. During charge, that reverses and the positive electrode of the cell is
the anode. The anode gives up electrons to the load circuit and dissolves into
the electrolyte.

Aqueous Batteries - Batteries with water-based electrolytes. The
electrolyte may not appear to be liquid since it can be absorbed by the
battery’s separator.

Actual Capacity or Available Capacity - The total battery capacity,
usually expressed in ampere-hours or milliampere-hours, available to perform
work. The actual capacity of a particular battery is determined by a number of
factors, including the cut-off voltage, discharge rate, temperature, method of
charge and the age and life history of the battery.

Battery - An electrochemical device used to store energy. The term is
usually applied to a group of two or more electric cells connected together
electrically. In common usage, the term “battery” is also applied to a single
cell, such as a AA battery.

Battery Capacity - The electric output of a cell or battery on a
service test delivered before the cell reaches a specified final electrical
condition and may be expressed in ampere-hours, watt- hours, or similar units.
The capacity in watt-hours is equal to the capacity in ampere-hours multiplied
by the battery voltage.

Battery Charger - A device capable of supplying electrical energy to a
battery.

Battery-Charge Rate - The current expressed in amperes (A) or milli
amps (mA) at which a battery is charged.

Cutoff Voltage, final - The prescribed lower-limit voltage at which
battery discharge is considered complete. The cutoff or final voltage is
usually chosen so that the maximum useful capacity of the battery is realized.
The cutoff voltage varies with the type of battery and the kind of service in
which the battery is used. When testing the capacity of a NiMH or NiCD battery
a cutoff voltage of 1.0 V is normally used. 0.9V is normally used as the
cutoff voltage of an alkaline cell. A device that is designed with too high a
cutoff voltage may stop operating while the battery still has significant
capacity remaining.

C - Used to signify a charge or discharge rate equal to the capacity of
a battery divided by 1 hour. Thus C for a 1600 mAh battery would be 1.6 A, C/5
for the same battery would be 320 mA and C/10 would be 160 mA. Because C is
dependent on the capacity of a battery the C rate for batteries of different
capacities must also be different.

Capacity - The capacity of a battery is a measure of the amount of
energy that it can deliver in a single discharge. Battery capacity is normally
listed as amp-hours (or milli amp-hours) or as watt-hours.

Cathode - Is an electrode that, in effect, oxidizes the anode or
absorbs the electrons. During discharge, the positive electrode of a voltaic
cell is the cathode. When charging, that reverses and the negative electrode
of the cell is the cathode.

Cell - An electrochemical device, composed of positive and negative
plates and electrolyte, which is capable of storing electrical energy. It is
the basic “building block” of a battery.

Charge - The conversion of electric energy, provided in the form of a
current, into chemical energy within the cell or battery.

Charge Rate - The amount of current applied to battery during the
charging process. This rate is commonly expressed as a fraction of the
capacity of the battery. For example, the C/2 or C/5.

Charging - The process of supplying electrical energy for conversion to
stored chemical energy.

Constant-Current Charge - A charging process in which the current
applied to the battery is maintained at a constant value.

Constant-Voltage Charge - A charging process in which the voltage
applied to a battery is held at a constant value.

Cycle - One sequence of charge and discharge.

Deep Cycle - A cycle in which the discharge is continued until the
battery reaches it’s cut-off voltage, usually 80% of discharge.

Shallow Cycling - Charge and discharge cycles which do not allow the
battery to approach it’s cutoff voltage. Shallow cycling of NiCd cells lead to
“memory effect”. Shallow cycling is not detrimental to NiMH cells and it is
the most beneficial for lead acid batteries.

Cycle Life - For rechargeable batteries, the total number of
charge/discharge cycles the cell can sustain before it’s capacity is
significantly reduced. End of life is usually considered to be reached when
the cell or battery delivers only 80% of rated ampere- hour capacity. NiMH
batteries typically have a cycle life of 500 cycles, NiCd batteries can have a
cycle life of over 1,000 cycles. The cycle of a battery is greatly influenced
by the type depth of the cycle (deep or shallow) and the method of recharging.
Improper charge cycle cutoff can greatly reduce the cycle life of a battery.

Direct Current (DC) - The type of electrical current that a battery can
supply. One terminal is always positive and another is always negative.

Discharge - The conversion of the chemical energy of the battery into
electric energy.

Depth of Discharge - The amount of energy that has been removed from a
battery (or battery pack). Usually expressed as a percentage of the total
capacity of the battery. For example, 50% depth of discharge means that half
of the energy in the battery has been used. 80% DOD means that eighty percent
of the energy has been discharged, so the battery now holds only 20% of its
full charge.

Discharge, deep - Withdrawal of all electrical energy to the end-point
voltage before the cell or battery is recharged.

Discharge, high-rate - Withdrawal of large currents for short intervals
of time, usually at a rate that would completely discharge a cell or battery
in less than one hour.

Discharge, low-rate - Withdrawal of small currents for long periods of
time, usually longer than one hour.

Drain - Withdrawal of current from a cell.

Dry Cell - A primary cell in which the electrolyte is absorbed
in a porous medium, or is otherwise restrained from flowing. Common practice
limits the term “dry cell” to the Leclanch‚ cell, which is the common
commercial type.

Electrochemical Couple - The system of active materials within a cell
that provides electrical energy storage through an electrochemical reaction.

Electrode - An electrical conductor through which an electric current
enters or leaves a conducting medium, whether it be an electrolytic solution,
solid, molten mass, gas, or vacuum. For electrolytic solutions, many solids,
and molten masses, an electrode is an electrical conductor at the surface of
which a change occurs from conduction by electrons to conduction by ions. For
gases and vacuum, the electrodes merely serve to conduct electricity to and
from the medium.

Electrolyte - A chemical compound which, when fused or dissolved in
certain solvents, usually water, will conduct an electric current. All
electrolytes in the fused state or in solution give rise to ions which conduct
the electric current.

Electropositivity - The degree to which an element in a galvanic cell
will function as the positive element of the cell. An element with a large
electropositivity will oxidize faster than an element with a smaller
electropositivity.

End-of-Discharge Voltage - The voltage of the battery at termination of
a discharge.

Energy - Output Capability - expressed as capacity times voltage, or
watt-hours.

Energy Density - Ratio of cell energy to weight or volume (watt-hours
per pound, or watt-hours per cubic inch).

Final Voltage (see Cutoff voltage)

Float Charging - Method of recharging in which a secondary cell is
continuously connected to a constant-voltage supply that maintains the cell in
fully charged condition. Typically applied to lead acid batteries.

Galvanic Cell - A combination of electrodes, separated by electrolyte,
that is capable of producing electrical energy by electrochemical action.

Gassing - The evolution of gas from one or both of the electrodes in a
cell. Gassing commonly results from self-discharge or from the electrolysis of
water in the electrolyte during charging.

Internal Resistance - The resistance to the flow of an electric current
within the cell or battery.

Memory Effect - A phenomenon in which a cell, operated in successive
cycles to less than full, depth of discharge, temporarily loses the remainder
of its capacity at normal voltage levels (usually applies only to Ni-Cd
cells). Note, memory effect can be induced in NiCd cells even if the level of
discharge is not the same during each cycle. Memory effect is reversable.

Negative Terminal - The terminal of a battery from which electrons flow
in the external circuit when the cell discharges. See Positive Terminal.

Nonaqueous Batteries - Cells that do not contain water, such as those
with molten salts or organic electrolytes.

Open-Circuit Voltage - The difference in potential between the
terminals of a cell when the circuit is open (i.e., a no-load condition).

Oxidation - A chemical reaction that results in the release of
electrons by an electrode’s active material.

Parallel Connection - The arrangement of cells in a battery made by
connecting all positive terminals together and all negative terminals
together. The voltage of the group remains the same as the voltage of the
individual cell. The capacity is increased in proportion to the number of
cells.

Polarity - Refers to the charges residing at the terminals of a battery.

Positive Terminal - The terminal of a battery toward which electrons
flow through the external circuit when the cell discharges. See Negative
Terminal.

Primary Battery - A battery made up of primary cells. See Primary Cell.

Primary Cell - A cell designed to produce electric current through an
electrochemical reaction that is not efficiently reversible. The cell, when
discharged, cannot be efficiently recharged by an electric current. Alakline,
lithium, and zinc air are common types of primary cells.

Rated Capacity - The number of ampere-hours a cell can deliver under
specific conditions (rate of discharge, end voltage, temperature); usually the
manufacturer’s rating.

Rechargeable - Capable of being recharged; refers to secondary cells or
batteries.

Recombination - State in which the gases normally formed within the
battery cell during its operation, are recombined to form water.

Reduction - A chemical process that results in the acceptance of
electrons by an electrode’s active material.

Seal - The structural part of a galvanic cell that restricts the escape
of solvent or electrolyte from the cell and limits the ingress of air into the
cell (the air may dry out the electrolyte or interfere with the chemical
reactions).

Secondary Battery - A battery made up of secondary cells. See Storage
Battery; Storage Cell.

Self Discharge - Discharge that takes place while the battery is in an
open-circuit condition.

Separator - The permeable membrane that allows the passage of ions, but
prevents electrical contact between the anode and the cathode.

Series Connection - The arrangement of cells in a battery configured by
connecting the positive terminal of each successive cell to the negative
terminal of the next adjacent cell so that their voltages are cumulative. See
Parallel Connection.

Shelf Life - For a dry cell, the period of time (measured from date of
manufacture), at a storage temperature of 21 degrees C (69 degrees F), after
which the cell retains a specified percentage (usually 90%) of its original
energy content.

Short-Ciruit - A condition that occurs when a short electrical path is
unintentionally created. Batteries can supply hundreds of amps if
short-circuited, potentially melting the terminals and creating sparks.

Short-Circuit Current - That current delivered when a cell is
short-circuited (i.e., the positive and negative terminals are directly
connected with a low-resistance conductor).

Starting-Lighting-Ignition (SLI) Battery - A battery designed to start
internal combustion engines and to power the electrical systems in automobiles
when the engine is not running. SLI batteries can be used in emergency
lighting situations.

Stationary Battery - A secondary battery designed for use in a fixed
location.

Storage Battery - An assembly of identical cells in which the
electrochemical action is reversible so that the battery may be recharged by
passing a current through the cells in the opposite direction to that of
discharge. While many non-storage batteries have a reversible process, only
those that are economically rechargeable are classified as storage batteries.
Synonym: Accumulator; Secondary Battery. See Secondary Cell.

Storage Cell - An electrolytic cell for the generation of electric
energy in which the cell after being discharged may be restored to a charged
condition by an electric current flowing in a direction opposite the flow of
current when the cell discharges. Synonym: Secondary Cell. See Storage Battery.

Taper Charge - A charge regime delivering moderately high-rate charging
current when the battery is at a low state of charge and tapering the current
to lower rates as the battery becomes more fully charged.

Terminals - The parts of a battery to which the external electric
circuit is connected.

Thermal Runaway - A condition whereby a cell on charge or discharge
will destroy itself through internal heat generation caused by high overcharge
or high rate of discharge or other abusive conditions.

Trickle Charging - A method of recharging in which a secondary cell is
either continuously or intermittently connected to a constant-current supply
that maintains the cell in fully charged condition.

Vent - A normally sealed mechanism that allows for the controlled
escape of gases from within a cell.

Volt - The unit of measurement of electromotive force, or difference of
potential, which will cause a current of one ampere to flow through a
resistance of one ohm. Named for Italian physicist Alessandro Volta
(1745-1827).

Voltage, cutoff - Voltage at the end of useful discharge. (See Voltage,
end-point.)

Voltage, end-point - Cell voltage below which the connected equipment
will not operate or below which operation is not recommended.

Voltage, nominal - Voltage of a fully charged cell when delivering
rated current.

Watt - A measurement of total power. It is amperes multiplied by volts.
120 volt @ 1 amp = 12 volts @ 10 amps.

Wet Cell - A cell, the electrolyte of which is in liquid form and free
to flow and move.