When your vehicle’s engine is off, the battery provides the required power to the rest of the system, as well as during start-up (cranking). It also supplements the power from the charging system during periods of high demand. Your vehicle’s electrical system powers everything from the ignition and fuel systems to accessories such as your radio, headlights and wipers. The electrical system is, in turn, powered by the engine. Here are the three key components of the electrical system: Battery, Charging System, Starting System.