Glossary Of Battery Terms

---

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.

 

Ampere-Hour Efficiency

The ratio of the output of a secondary cell or battery, measured in ampere-hours, to the input required to restore the initial state of charge, under specified conditions (also coulombic efficiency).

 

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 situation reverses and the positive electrode of the cell is the anode.

Battery

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 applied to a single cell.

 

Bobbin

A cylindrical electrode (usually the positive) pressed from a mixture of the active material, a conductive material, such as carbon black, the electrolyte and/or binder with a centrally located conductive rod or other means for a current collector.

Capacity

The total number of ampere-hours (or watt-hours) that can be withdrawn from a cell/battery under specified conditions of discharge.

 

Cathode

The electrode in an electrochemical cell where reduction takes place. During discharge, the positive electrode of the cell is the cathode. During charge, the situation reverses, and the negative electrode of the cell 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 a current from an external source, into chemical energy within a cell or battery.

 

Closed Circuit Voltage (CCV)

The difference in potential between the terminals of a cell/battery when it is discharging (on- load condition).

 

Continuous Discharge

A test in which a cell/battery is discharged to prescribed cut-off voltage.

 

Cumulative Capacity

The total number of ampere-hours (or watt hours) that can be withdrawn from a cell/battery under specified conditions of discharge over a predetermined number of cycles or the cycle life.

 

Cut-Off Voltage

The cell/battery voltage at which the discharge is terminated.

 

Cycle

The discharge and subsequent charge of a rechargeable cell/battery is called a cycle.

 

Cycle Life

The number of cycles under specified conditions which were available from a rechargeable cell/battery before it fails to meet specified criteria as to performance.

Deep Discharge

Withdrawal of at least 80% of the rated capacity of a cell/battery.

 

Depth of Discharge

The ratio of the quantity of electricity (usually in ampere-hours) removed from a cell/battery on discharge to its rated capacity (usually expressed in %).

 

Discharge

The conversion of chemical energy of a cell/battery into electrical energy and withdrawal of the electrical energy into a load.

 

Discharge Rate

The rate, usually expressed in amperes, at which electrical current is taken from the cell/battery.

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.

 

Energy Density

The ratio of the energy available from a cell or battery to its volume (Wh./L). Also used on a weight basis (Wh/kg).

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.

Intermittent Test

A test during which a cell or battery is subjected to alternate periods of discharge and rest according to a specified discharge regime.

 

Ion

A particle in solution that can carry a negative or positive charge.

Leakage

Leakage appears as a clear caustic or white solid at the negative terminal of a RAM cell.

 

Life

For rechargeable batteries, the duration of satisfactory performance, measured in years (float life) or in the number of charge/discharge cycles (cycle life).

 

Load

A load is an energy consuming device. The device can be an actual device such as a bulb of a flash light, radio, cassette player, motor, etc., a resistor or a constant current load.

Memory Effect

A phenomenon in which a cell, operated in successive cycles to the same, but less than a full, depth of discharge experiences a depression of its discharge voltage and temporarily loses the rest of its capacity at normal voltage levels.

Negative Electrode

The electrode acting as an anode when a cell or battery is discharging.

Open Circuit Voltage (OCV)

The difference in potential between the terminals of a cell/battery when the circuit is open (no-load condition).

 

Overcharge

Discharge past the point where the full capacity of the cell has been obtained.

Positive Electrode

The electrode acting as a cathode when a cell or battery is discharging.

 

Power Density

The ratio of the power available from a battery to its weight (W/kg) or volume (W/L). Also used on a weight basis (W/Kg).

 

Primary Cell (or Battery)

A cell or battery which is not intended to be recharged and is discarded when the cell or battery has delivered all its electrical energy.

Rated Capacity

The number of ampere-hours a cell/battery can deliver under specific conditions (rate of discharge, cut-off voltage, temperature).

 

Recharge/Charge

The conversion of electrical energy, provided in the form of a current from an external source (charger), into chemical energy within a cell/battery.

Secondary Battery

A galvanic battery which, after discharge, may be restored to the fully charged state by the passage of an electric current though the cell in the opposite direction to that of discharge.

 

Self Discharge

The loss of useful capacity of a cell or battery due to internal chemical action.

 

Separator

An ion permeable, electronically nonconductive, spacer or material which prevents electronic contact between electrodes of opposite polarity in the same cell.

 

Series

The interconnection of cells or batteries in such a manner that the positive terminal of the first is connected to the negative terminal of the second, and so on. Series connections increase the voltage of the resultant battery.

 

Service Life

The period of useful like (usually in hours or minutes) of a primary cell/battery before a predetermined cut-off voltage is reached.

 

Shallow Discharge

Withdrawal of less than 50% of the rated capacity of a cell/battery.

 

Shelf Life

The duration of storage under specified conditions at the end of which a cell or battery still retains the ability to give a specified performance.

Taper Charge

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

 

Trickle Charge

A charge at a low rate, balancing losses through a local action and/or periodic discharge, to maintain a cell or battery in a fully charged condition.

Vent

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