Charging System: Description and Operation

(Figure 1) SI Alternator (Typical):

Regulator In Charging Circuit:

GENERAL DESCRIPTION
The basic charging system is the SI integral regulator charging system. The internal components are connected electrically as shown in figure 1. The alternator used on individual vehicles will be one of the following types: 10 SI, 12 SI, 15 SI, or a 17 SI. The 15 SI and 17 SI alternators have delta stator windings and cannot be checked for opens. The other differences among the four (4) types are output current ratings, and drive end and slip ring end bearing stack up.

The brown field wire to the alternator is used to turn on the alternator. The 10 ohm resistance, provided by either the alternator warning lamp, choke heater relay or the resistance wire is needed to protect the diode trio.

Several models of alternators are available with different output ratings. Their basic operating principles are the same.

The alternator features a solid state regulator that is mounted inside the alternator. All regulator components are enclosed into a solid mold, and this unit along with the brush holder assembly is attached to the slip ring end frame. The regulator voltage setting cannot be adjusted.

The alternator rotor bearings contain enough grease to eliminate the need for periodic lubrication. Two brushes carry current through the two slip rings to the field coil mounted on the rotor, and under normal conditions will provide long periods of attention-free service. No periodic adjustments or maintenance of any kind are required on the entire alternator assembly.

The stator windings are assembled on the inside of a laminated core that forms part of the alternator frame. A recitifier bridge connected to the stator windings contains six diodes, and electrically changes the stator A/C voltages to a D/C voltage which appears at the alternator output terminal. Alternator field current is supplied through a diode trio which also is connected to the stator windings. A capacitor condenser, mounted in the end frame protects the rectifier bridge and diode trio from high voltages, and suppresses radio noise.