The alternator generates direct current for recharging the battery and for powering vehicle electrical loads.

The alternator consists of a spinning set of electrical windings called a rotor, a stationary set of windings called a stator, a rectifier assembly, a set of brushes to maintain electrical contact with the rotor, and a pulley. All of these parts except the pulley are contained in an aluminum housing. Today's alternators use compact, electronic voltage regulators that may be housed inside the alternator or the voltage regulator function may be handled by the vehicle's powertrain control module (PCM).