4-01
Charging System
4-01
Part 4 Charging System
COMPONENT INDEX
Page
COMPONENT INDEX
Page
DESCRIPTION AND OPERATION
Alternator ................................................
DIAGNOSIS AND TESTING
ADJUSTMENTS
MOTOROLA .................................................
Belt Adjustments ..................................
4-07
DIAGNOSIS AND TESTING
REMOVAL AND INSTALLATION ...............
4-08
DESCRIPTION AND OPERATION
the alternator stator terminal reaches about 3 volts, the
The Alternator charging system is a negative
regulator field relay closes. This puts the same voltage
ground system, and consists of an alternator, a regulator,
potential on both sides of the charge indicator lamp
a charge indicator, a storage battery, and associated
causing it to go out. When the field relay has closed,
wiring.
current passes through the regulator A terminal and is
The alternator is belt driven from the engine.
metered to the alternator field.
Current is supplied from the alternator-regulator system
If an ammeter is used in the charging system
to the rotating field of the alternator through two brushes
(Figure 2), the regulator I terminal and the alternator
to two slip rings.
stator terminal are not used. When the ignition switch is
The alternator produces power in the form of
turned ON, the field relay closes and electrical current
alternating current. The alternating current is rectified to
passes through the regulator A terminal and is metered
direct current by six diodes. The alternator regulator
to the alternator field. When the engine is started, the
automatically adjusts the alternator field current to
alternator field rotates causing the alternator to operate.
maintain the alternator output voltage within prescribed
The ammeter indicates current flow into (charge) or out
limits to correctly charge the battery.
of (discharge) the vehicle battery.
If a charge indicator lamp is used in the charging
system (Figure 1) the system operation is as follows:
When the ignition switch is turned ON, a small electrical
current flows through the lamp filament (turning the lamp
ON) and through the alternator regulator to the alternator
field. When the engine is started, the alternator field
rotates and produces a voltage in the stator winding.
When the voltage at
FIG. 1. Alternator Charging System - Indicator Light
