Exploded view of an automotive alternator. The engine's turning crankshaft, connected to the …—© Merriam-Webster Inc.

Source of direct electric current in modern vehicles for ignition, lights, fans, and other uses. The electric power is generated by an alternator mechanically coupled to the engine, with a rotor field coil supplied with current through slip rings, and a stator with a three-phase winding. A rectifier converts the power from alternating to direct form. A regulator ensures that the output voltage is properly matched to the battery voltage as engine speed varies. An inductor alternator is a special kind of synchronous generator in which both the field and the output winding are on the stator.

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