Westerbeke 8.0KW-60Hz Service Manual page 61

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ALTERNATORS TESTING/TROUBLESHOOTING
TESTING THE ALTERNATOR
A
CAUTION:
Before starting the engine make
certain that everyone is clear of moving parts! Keep
away from sheaves and belts during test procedures.
1. Start the Engine.
2.
Mrer
the engine has
run
for a few
minutes, measure
the
starting battery voltage
at
the battery teIDJinals using a
multimeter set on
DC
volts.
a. If the voltage
is
increasing toward 14 volts, the
alternator
is
working.
b.Ifthe voltage remains around 12 volts, a problem
exists with either the alternator or the charging circuit;
continue with Steps 3 through 6,
MEASURING
BAnEBY VOLTAGE
(ENGINE RUNNING)
3. Thrn off the engine.
~pect
all wiring and connections.
Ensure that the battery teIDJinals and the engine ground
connections are tight and clean
4. If a battery selector switch
is
in the charging circuit,ensure
t\1at it
is
on the correct setting.
5. Check the battery voltage. If your battery is in good
condition the reading should be 12 to 13 volts.
MEASURING
BAnEBY VOLTAGE
ENGINE OFF)
TESTING THE
1. Connect the positive probe to the output terminal B and
connect the negative probe to ground.
2. Wiggle the engine wiring harness while observing the
voltmeter. The meter should indicate the approximate
battery voltage, and should not vary. If no reading is
obtained, or
if
the reading varies, check the alternator
output circuit for loose or
dirty
connections or
. damaged wiring.
3. Start the engine.
4. Repeat the same measurement, the negative probe to
ground, the positive probe to B with the engine runuing.
The voltage reading should be between 13.5 and 14.5
volts. If your alternator is over or under-charging, have
it repaiJed
at
a reliable service shop.
5. If the preVious test reads only battery voltage at
termlnaI B, use the meter to measure the
DC
excitation
terminal. If 12 volts is not present at exciter terminal
R,
inspect the wiring for breaks and poor oonnections. .
Jump 12 volts from a 12 volt source (such as the
battery) and operate the alternator. If the voltage output
is 13-14 volts; .• then the alternator
is
OK.
TESTING THE OUTPUT
CIRCUIT ENGINE RUNNING
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... WESTERBEKE
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Englneil & Generators
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