Our glossary is here to help to cut through the jargon and understand technical terms used in the battery world.

Active Material

The active chemical material used in the manufacturing of positive and negative electrodes.

Absorbent Glass Mat (AGM)

AGM is type of Lead Acid Battery (dry cell) which uses glass fiber matting to promote the recombination of gasses caused by charging.


A unit of measurement for electric current.

Ampere-Hour (Ah or Amp)

Used to indicate the capacity of a battery. Also referenced as Ah or Amp.


Two or more cells connected in series or parallel.


A Battery Management System used to manage charge & discharge and monitor SOC (state of charge) & SOH (State of health) data to protect the battery and maximise performance.


The discharge capacity as stated by the manufacturer which may be obtained at a given discharge rate and temperature.


The fundamental structure of a battery composed of positive and negative plates as well as electrolyte.


The conversion of electrical energy to chemical energy; the process which restores electrical energy to a cell or battery.

Cut-off Voltage

A final voltage of a battery or cell after discharge.


A single charge and discharge of a battery.

Cycle life

The amount of cycles a battery can deliver before it reaches end of life.

Deep Cycle

A cycle in which the discharge continues until the battery reaches its cut-off voltage.

Direct Current(DC)

The type of electrical current output from a battery.


The process of drawing current from a battery.

Depth of Discharge (DoD)

The capacity discharged from a battery expressed as a percentage.

  • Self-Discharge – capacity loss while the battery is stored or not in use.


The withdrawal of power from a battery.

  • Parasitic drain – when a drain is present on a battery even when the application or vehicle is off.


Conducts ions in a cell. This is part of the manufacturing stage.

Gas Recombination

The process by which oxygen gas generated from the positive plate during the final stage of charging is absorbed into the negative plate, preventing the loss of water.

Internal Resistance (IR)

Internal resistance inside a battery which can create a voltage drop.

Leisure Battery

A battery which has high cycle life. See also Deep cycle..

Nominal Capacity

The nominal value of rated capacity. (Ah).

Nominal Voltage

The nominal value of rated voltage. (V)

Open Circuit Voltage(OCV)

A voltage reading of a battery without any load or connections present.


The continuous charging of a battery after it reaches 100% SOC. This will reduce battery life with prolonged exposure.

Parallel Connection

The installation and connection of batteries by linking all terminals of the same polarity. This increases the available capacity (Ah) in the battery bank.


Often used to describe the layout or location of the battery terminals.


The process in which gasses formed within the battery during normal operation are recombined to form water.

Series Connection

The installation and connection of batteries by linking terminals of opposite polarity. This increases the voltage (V) of the battery bank.

Service Life

The expected life of a battery expressed in total cycles or years of standby.

Shelf Life

A period a battery can be stored without a charge being applied.

State of Charge(SOC)

The available capacity of a battery at a given time.

State of Health(SOH)

Reflects battery performance by verifying capacity, current delivery, voltage and self-discharge; measured as a percentage.


The formation/crystallization of lead sulfate on the surface of the plates. Excessive sulfation will cause inefficiencies and poor performance of the battery.

Thermal Runaway

This is caused by internal heat generation exceeding the amount of heat that is dissipated to its surroundings.


Ampere (A) multiplied by volt (V) equals watts (W).