Nominal capacity

Nominal capacity is the rated or nameplate amount of energy a battery can store when new, usually shown in kilowatt hours (kWh) for home battery systems. It is not always the same as usable capacity: a datasheet may list a nominal capacity and a smaller usable capacity after depth of discharge, reserve, battery management and other operating limits are applied. It is also different from charge power or discharge power, which describe how quickly the battery can accept or supply energy. The figure matters when comparing battery documents because warranties, state-of-health readings and retained-capacity terms may use nominal capacity, rated capacity or usable capacity as their baseline. Read the capacity figure with the product's usable-capacity line, depth-of-discharge limit, operating-temperature range, power limits and warranty conditions rather than treating every labelled kilowatt hour as available in every circumstance.