ALTERNATOR/REGULATOR TEST PROCEDURE
General
It
is desirable to test the charging system (alternator and voltage regulator) in the vehicle using the
vehicle wiring harness and electrical loads that are a permanent part of the system. In-vehicle
testing will then provide the technician with
an
operational test of the charging system
as
well
as
the major components of the electrical system.
Preliminary Checks & Tests
Before starting the
actual electrical test procedure, the charging system, battery and wiring should
be
checked to eliminate possible problem areas. The following procedure is recommended:
1.
Check the condition and adjustment of belts.
A.
If the alternator fan can
be
moved by pushing on a fan blade with your finger, the belts
should
be
adjusted.
B.
Replace any worn or glazed belts.
2.
Check
to
see that all terminals, connectors and plugs are clean and tight.
A.
Loose or corroded connections cause high resistance and this could cause
overcharging, undercharging or damage to the charging system.
B.
Badly corroded battery cables could prevent the battery from reaching a fully charged
condition.
3.
Check battery condition and change if necessary. A low or discharged battery may cause
false or misleading readings
on
the in-vehicle tests.
Test Equipment Requirements
The
Alternator and Regulator tests outlined require electrical test equipment to measure voltage
only;
however, most commercial test equipment incorporates several testing devices in a single
unit.
DC
VOLTMETER: 0-20 Volt Scale
BATTERY
TEST
EQUIP.:
Any commercial type, Hydrometer with temperature correction scale.
Storage
Battery
The
vehicle storage battery circuit represents a continuous although variable electrical load to the
alternator. If the circuit,
pOSition
or negative, is opened or broken while the alternator is charging,
the
loss of the battery will result
in
the charging voltage rising to unsafe levels.
Battery Inspection
The following table illustrates typical ranges of specific gravity for a cell in various states of charge.
THE
BATTERY
MUST
BE
AT
LEAST 75% OF FULL CHARGE
FOR
EFFECTIVE
ALTERNATOR
TESTING.
1.260
SP.
GR
1.280
SP.
GR.
CHARGE
BATTERY
BATTERY
STATE
1.260 Sp.
Gr.
1.280
Sp.
Gr.
100% Charged
1.230
Sp.
Gr.
1.250
Sp.
Gr.
75%
Charged
1.200
Sp.
Gr.
1.220
Sp.
Gr.
50%
Charged
1.170
Sp.
Gr.
1.190
Sp.
Gr.
25%
Charged
1.140
Sp.
Gr.
1.160
Sp.
Gr.
Very Low Cap.
1.110
Sp.
Gr.
1.130 Sp.
Gr.
Discharged
After completing these preliminary checks and tests, proceed with the tests
as
outlined in the
Trouble-Shooting Guide.
79
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