Alternator: Description and Operation

The ``B'' terminal is connected internally to the rectifier bridge output. Externally, the cable connected to the ``B'' terminal supplies Direct Current (DC) output to the electrical system to charge the battery and operate vehicle accessories while the engine is running.

The ``L'' terminal is connected internally (through a network of integrated circuits) to the field coil. When the ignition switch is turned on, the field coil is energized to ``turn on'' the regulator power transistor.

The ``S'' terminal is connected internally to the voltage regulator sensing circuit. Externally, the ``S'' terminal is connected to the ignition side of the ignition switch. The ``S'' circuit is used to tell the voltage regulator how much alternator output is required.

The Integrated Circuit (IC) electronic voltage regulator is part of the rotor, brush, and brush holder assembly. There is no voltage adjustment. The IC regulator automatically reduces regulated voltage when the ambient temperature increases, so that battery charging voltage is maintained at the correct level.