Voltage, capacity, and energy

Voltage describes the potential difference between two measurement points and is commonly expressed in volts. Readings can differ at rest, under load, during charge, during discharge, and during pulses, so a voltage record needs its measurement state and direction rather than treating one reading as fixed for every condition.

Capacity is charge released or accepted between a defined start point and cutoff, commonly expressed in ampere-hours. Rate, temperature, voltage cutoff, and rest strategy can alter the result for that interval, so a capacity record needs the test protocol, sample state, and repeatability information.

Energy can be written as E = ∫V dQ, the integral of voltage over charge, and is commonly expressed in watt-hours. Nominal voltage multiplied by capacity is only an approximation when its voltage and charge ranges are explicit; this basic relation checks whether units, direction, and integration interval are consistent.