The Car Generator🚘🚗 In modern vehicles, the alternator is the component that functions as the car's generator. Its primary role is to produce electricity to power the car's ignition system, lights, and other accessories, as well as to recharge the car battery while the engine is running. How an Alternator Works The alternator is typically bolted to the engine and is driven by a serpentine or drive belt. As the engine runs, it rotates the alternator, which converts mechanical energy into electr