Alternator: Description and Operation

The charging system generators use a built-in voltage regulator with fault detection, a stator, rectifier bridge, and rotor with slip rings and brushes. The CS-130D generator used on the 3800 (VIN K) engine uses a conventional pulley and dual internal cooling fans to cool the slip ring end frame, rectifier bridge and voltage regulator. The CS-144 generator used on the 5.7L (VIN P) engine uses a conventional pulley and fan to cool the slip ring end frame, rectifier bridge and voltage regulator. These generators use only two connections - battery positive and "L" terminal, in addition to the ground path through the generator bracket. Use of "P," "1" and "S" terminals is optional. The "P" terminal is connected to the stator and may be connected externally to a tachometer or other device. The "I" terminal can be connected directly to battery voltage to power the generators instead of, or in addition to, the "L" terminal which must be stepped down. The "S" terminal may be connected to an external voltage source, such as voltage near the battery, for voltage control. If the "S" terminal is not used, internal generator voltage is used for control.
The voltmeter reads battery voltage when the engine is not running and reads charging system voltage when the engine is running. The normal indication is between 11 volts and 16 volts.

The regulator voltage setting varies with temperature and limits system voltage by controlling, rotor field current. While the field current is "on,' this regulator actually switches rotor field current on and off at a fixed frequency of about 400 cycles per second to help control radio noise. By varying the overall on-off time, correct average field current for proper system voltage control can be obtained. At high speeds, the on-time may be 10 percent and the off-time 90 percent. At low speeds, with high electrical loads, on-0ff time may be 90 percent and 10 percent respectively.