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/I 0 = 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The total number of ampere-hours or watt-hours that can be withdrawn from a fully charged cell or battery under specified conditions of discharge.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 Offset
A correction factor applied to the rating of a battery if discharged under different C-rates from the one rated.

Capacity Retention (or Charge Retention)
The fraction of the fall capacity available from a battery under specified conditions of discharge after it has been stored for a period of time

Carbon/Zinc
A primary battery (non-rechargeable) commonly used in low drain consumer applications (i.e.: clocks, calculators, garage door openers, etc.). Available in the same sizes as the Alkaline and Manganese Dioxide. The Carbon/Zinc is one of the most widely used dry primary batteries because of its low cost and reliable performance.

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.

Cell Mismatch
Cells within a battery pack that contain different capacity and voltage levels.

Cell Reversal
The stronger cells of a battery (several cells connected in series) impose a voltage of reverse polarity across a weaker cell during a deep discharge.

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.

Condition
A process that utilizes a series of heavy discharges and recharges on a battery to assure optimum performance.

Constant Current
A battery discharge regime whereby the current drawn during the discharge Discharge remains constant.

Constant Power
A battery discharge regime whereby the current during the discharge increases as the battery voltage decreases.

Constant Resistance
A battery discharge regime whereby the resistance of the equipment load remains constant throughout discharge.

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.

Current Limiting Chargers
A charger that keeps the charge current constant during the charge process but allows the voltage to Fluctuate (typically used on NiCd and NiMh chargers).

Cutoff 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
A sequence where a charged battery is discharged and recharged.

Cycle Life
The number of cycles under specified conditions that are available from a secondary battery before it fails to meet specified criteria as to performance.

Cylindrical Cell
The positive and negative plates are rolled up and placed into a cylindrical container (as opposed to stacking the plates in a prismatic cell design).