The charging system is a negative (-) ground system that consists of an alternator, a voltage regulator, a charge indicator, a storage battery, wiring connecting the components, and fuse link wire.
The alternator is driven by a belt from the engine. Energy is supplied from the alternator/regulator system to the rotating field through two brushes to two slip-rings. The slip-rings are mounted on the rotor shaft and are connected to the field coil. This energy supplied to the rotating field from the battery is called excitation current and is used to initially energize the field to begin the generation of electricity. Once the alternator starts to generate electricity, the excitation current comes from its own output rather than the battery.
The alternator produces power in the form of alternating current (AC). The alternating current is rectified by diodes into direct current (DC). The direct current is used to charge the battery and power the rest of the electrical system.
When the ignition key is turned ON , current flows from the battery, through the charging system indicator light on the instrument panel, to the voltage regulator, and to the alternator. Since the alternator is not producing any current, the alternator warning light will flash. When the engine is started, the alternator begins to produce current, turning off the alternator light. As the alternator turns and produces current, the current is divided in two ways: one part to charge the battery and power the electrical components of the vehicle, and the rest is returned to the alternator to enable it to increase its output. In this situation, the alternator is receiving current from the battery and from itself. A voltage regulator is wired into the current supply to the alternator to prevent it from receiving too much current, which, in turn, would cause it to produce too much current. Conversely, if the voltage regulator does not allow the alternator to receive enough current, the battery will not be fully charged and will eventually drain.
The battery is connected to the alternator at all times, whether the ignition key is turned ON or not. If the battery were shorted to ground, the alternator would also be shorted. This would damage the alternator. To prevent this, a fusible link is installed in the wiring between the battery and the alternator. If the battery is shorted, the fusible link melts, thereby protecting the alternator.