Westerbeke 5.0Kw BCDR Operator's Manual page 33

ALTERNATORS TESTING/TROUBLESHOOTING
PRELIMINARY INSPECTION
Before starting the actual alternator and voltage regulator,
testing the following checks are recommended.
1. Make certain your alternator is securely mounted.
2. Check the drive belts for proper tension. Replace the
~lt
if it is worn or glazed.
3. Check that all terminals, connectors and plugs are clean
and tight. Loose or corroded connections cause high
resistance and this could cause overcharging,
undercharging or damage to the charging system. Badly
corroded battery cables could prevent the battery from
reaching a fully charged condition.
4. Check the condition of the battery and charge if necessary.
A low or discharged battery may cause false or misleading
readings in the tests.
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. After the engine has run for a few minutes, measure the
starting battery voltage at the battery terminals using a
multimeter set on DC volts.
a. If the voltage is increasing toward 14 volts, the
alternator is working.
b. If the voltage remains around 12 volts, a problem
exists with either the alternator or the charging circuit;
continue with Steps 3 through 8.
MUlTIMETER ~ir!j-
'ij~~~~~~
MEASURING
~
BAlTERY
~-,.
-YOLTAGE
ENGINE RUNNING
3. 'fum off the engine. Inspect all wiring and connections.
Ensure that the battery terminals and the engine ground
connections are tight and clean
s.
'fum on the ignition switch, but do not start the engine.
6. Check the battery voltage. If your battery is in good
condition the reading should be 12 to 13 volts.
TESTING THE OUTPUT CIRCUIT
MEASURING
BATTERY VOLTAGE
(IGNITION ON
ENGINE OFF)
1. Connect the positive probe to the output terminal B and
connect the negative probe to the ground terminal E on
the alternator.
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 E,
the positive probe to B with the engine running. The
voltage reading should be between 13.5 and 14.5 volts.
If your alternator is over or under-charging, have it
repaired at a reliable service shop.
S. If the
prev~ous
test reads only battery voltage at
terminal 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 connections.
Jump 12 volts from a 12 volt source (such ad the
battery) and operate the alternator. If the voltage output
is
13~14
volts,m then the alternator is OK.
Engines & Generators
29