Battery Terminology Guide
Essential battery terms and definitions to help you understand battery specifications, performance characteristics, and technical documentation.
A
A unit of electric charge that measures battery capacity. One ampere-hour represents the amount of charge that flows when a current of one ampere is sustained for one hour.
The negative electrode in a battery during discharge. It releases electrons to the external circuit and undergoes oxidation.
C
The rate at which a battery is charged or discharged relative to its capacity. A 1C rate means the battery is discharged in one hour.
The total amount of electrical energy a battery can store and deliver, typically measured in ampere-hours (Ah) or watt-hours (Wh).
The positive electrode in a battery during discharge. It accepts electrons from the external circuit and undergoes reduction.
The number of complete charge and discharge cycles a battery can perform before its capacity degrades to a specified level (typically 80% of original capacity).
D
A battery designed to be regularly discharged to a significant portion of its capacity (typically 50-80%) and then recharged.
The percentage of battery capacity that has been discharged. A 50% DoD means half the battery's energy has been used.
The current at which a battery is discharged, often expressed as a multiple of the battery's capacity (C-rate).
E
The chemical medium that allows ion flow between the positive and negative electrodes inside a battery.
The amount of energy stored per unit mass or volume, typically expressed in Wh/kg (gravimetric) or Wh/L (volumetric).
I
The inherent resistance within a battery that opposes current flow, causing voltage drop and heat generation during operation.
L
The device or circuit that draws current from the battery, determining the discharge rate and runtime.
M
A phenomenon where batteries "remember" partial discharge cycles and lose capacity if not fully discharged regularly. Most common in NiCd batteries.
N
The typical operating voltage of a battery during normal discharge conditions, used for rating and comparison purposes.
P
The amount of power a battery can deliver per unit mass or volume, typically expressed in W/kg or W/L.
R
The duration a battery can power a specific load before requiring recharge, dependent on capacity, load current, and operating conditions.
S
The gradual loss of charge in a battery when not in use, typically expressed as a percentage per month.
The current charge level of a battery expressed as a percentage of its full capacity. 100% SoC means fully charged.
A measure of a battery's condition compared to its ideal state, typically expressed as a percentage of original capacity.
T
The rate at which battery capacity or voltage changes with temperature, important for compensation in critical applications.
A dangerous condition where increasing temperature causes chemical reactions that generate more heat, potentially leading to fire or explosion.
V
The reduction in voltage from no-load to loaded conditions, caused by internal resistance and external circuit resistance.
W
A unit of energy equal to one watt of power sustained for one hour. Calculated as voltage × ampere-hours.