As an accessory, the battery is used as the power supply, mainly for starting the engine, or for power supply of other electrical facilities when the engine is not running. The power loss of the battery can be charged by the engine driven alternator, and the battery can be reused.

Accessories refer to parts or components for assembling machinery; It also refers to the parts or components that are reinstalled after being damaged. Accessories can be divided into standard accessories and optional accessories. Therefore, the battery is replaceable and therefore a spare part.