Charging System: Description and Operation

CHARGING SYSTEM
Generator Operation
The generator provides voltage to operate the vehicle's electrical system and charge the battery. The regulator supplies current to the field coil of the rotor. When current flows through the field coil, a magnetic field is created. This field rotates as the rotor is driven by the engine, creating an AC voltage and current in the stator windings. This AC signal is converted to DC by the rectifier bridge and available to the vehicle's electrical system at the "BAT" terminal.

Constant Voltage Supply
The generator must supply sufficient current to all vehicle electrical loads, especially for charging the vehicle's battery. Since the rotor speed varies with engine speed, the generator must also maintain the output voltage at a constant value. The generator's regulator supplies current to the field coil of the rotor thus controlling the output voltage of the generator. When the ignition switch is turned to "RUN," battery voltage is supplied through the IGN fuse to the generator at terminal "F", turning on the regulator on vehicles equipped with a 3.1L (VIN D) Engine. On vehicles equipped with a 3.8L (VIN L) engine, battery voltage is supplied to the generator at terminal "L" from the Powertrain Control Module (PCM), turning on the regulator.

Voltage Regulator
The regulator creates a weak magnetic field in the field coil when the engine is being started. The regulator senses generator rotation by detecting an AC voltage at the Stator through an internal wire. Once the engine is running, the regulator can monitor the internal AC voltage and DC output at the "BAT" terminal, as well as the external battery voltage at terminal "S." The regulator will then vary the current in the field coil of the rotor as needed, to provide a constant output voltage and adequate current to the electrical system of the vehicle.