Automotive battery

An automotive battery, or car battery, is a usually 12 Volt lead-acid rechargeable battery that is used to start a motor vehicle, and to power lights, screen wiper etc. while the engine is off.

Its main purpose is to provide an electric current to the electric-powered starting motor, which in turn starts the chemically-powered internal combustion engine that actually propels the vehicle. Once the engine is running, power for the car's electrical systems is still supplied by the battery, with the alternator charging the battery as demands increase or decrease.