The alternator is a device that converts mechanical energy into electrical current. In a car, the alternator is used to charge the battery and power the electrical equipment while the engine is running.

The alternator first appeared on a car in 1912 as a single device along with the starter. However, later they were separated due to the difference in tasks, different designs, as well as for the convenience of repair. Today, the alternator and starter in a car are two different devices that perform different functions.