Cadmium
A metal used in about the shape of a pencil for obtaining voltage of positive or negative plates. It is dipped in the electrolyte but not allowed to come in contact with plates.
Capacity
The capacity of a battery is specified as the number of Amp-Hrs that the battery will deliver at a specific discharge rate and temperature. The capacity of a battery is not a constant value and is seen to decrease with increasing discharge rate. The capacity of a battery is affected by a number of factors such as: active material weight, density of the active material, adhesion of the active material to the grid, number, design and dimensions of plates, plate spacing, design of separators, specific gravity and quantity of available electrolyte, grid alloys, final limiting voltage, discharge rate, temperature, internal and external resistance, age, and life history of the battery.
Case
The containing box which holds the battery cells.
Cell
The basic electrochemical current-producing unit in a battery, consisting of a set of positive plates, negative plates, electrolyte, separators, and casing. In a lead-acid battery the cell has an open-circuit voltage of approximately 2-volts. There are six cells in a 12-volt lead-acid battery.
Charge
Passing direct current through a battery in the direction opposite to that of discharge, in order to put back the energy used on discharge.
Charge Rate
The proper rate of current to use in charging a battery from an outside source. It is expressed in amperes and varies for different sized cells.
Circuit
An electrical circuit is the path followed by a flow of electrons. A closed circuit is a complete path. An open circuit has a broken, or disconnected, path.
Circuit (Series)
A circuit that has only one path for the flow of current. Batteries arranged in series are connected with negative of the first to positive of the second, negative of the second to positive of the third, etc. If two 12-volt batteries of 50 ampere-hours capacity each are connected in series, the circuit voltage is equal to the sum of the two battery voltages, or 24 volts, and the ampere-hour capacity of the combination is 50 ampere-hours.
Circuit (Parallel)
A circuit that provides more than one path for the flow of current. A parallel arrangement of batteries (usually of like voltages and capacities) has all positive terminals connected to a conductor and all negative terminals connected to another conductor. If two 12-volt batteries of 50 ampere-hour capacity each are connected in parallel, the circuit voltage is 12 volts, and the ampere-hour capacity of the combination is 100 ampere-hours.
Cold Crank Rating
The cold crank rating refers to number of amperes a lead-acid battery at 0°F (-17.8°C) can deliver for 30 seconds and while maintaining at least 7.2 volts (1.2 volts per cell). This is commonly referred to as CCA (Cold Cranking Amps).
Conductance
The ability to transmit current in a circuit or battery.
Container and Cover
The reservoir and lid containing the battery parts and electrolyte made from impact and acid resistant material such as polypropylene.
Corrosion
The chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties. The positive lead grids in a battery gradually corrode in service often leading to battery failure. Battery terminals are subject to corrosion if they are not properly maintained.
Current
The rate of flow of electricity, or the movement of electrons along a conductor. It is comparable to the flow of a stream of water. The unit of measure for current is the ampere.
Current (Alternating) (AC)
A current that varies periodically in magnitude and direction. A battery does not deliver alternating current (AC).
Current (Direct) (DC)
An electrical current flowing in an electrical circuit in one direction only. A secondary battery delivers direct current (DC) and must be recharged with direct current in the opposite direction of the discharge.
Cycle
In a battery, one discharge plus one recharge equals one cycle.