Westerbeke 8.0KW-60Hz Service Manual page 62

ALTERNATORS TESTlNG/TROUBLESHOOTlNG
TESTING THE EXCITATION CIRCUIT
1. Connect the positive (+) multimeter probe to the
excitation terminal R on the alternator and the negative
(-) lead to ground.
2. Thrn the ignition switch to the on position and note
the multimeter reading. The reading should be 1.3 to
2.5
volts (see illustration). .
OUTPUT TERMINAL
TESTING THE
EXCITATION
CIRCUIT.
(ENGINE"·
RUNNING)
3. If the reading is between .7S and 1.1 volts, the
rotor field circuit probably is shorted or grounded.
4. If the reading is between 6.0 and 7.0 volts, the rotor
field circuit probably is open.
S. If no reading is obtained, an open exists in the
alternator-excitation lead or in the excitation circuit of
the regulator. Disconnect the lead from exc terminal R.
Connect the positi,ve multimeter probe to the excitation
lead and the negative multimeter probe to ground.
If the multimeter now indicates an approximate battery
voltage, the voltage regulator is defective and must be
replaced. If no voltage is indicated, check the
excitation circutt for loose or
dirty
connections or
damaged wiring.
OUTPUT TERMINAL
CHECKING THE SERVICE BATTERY
Check the voltage of the service battery. this battery should
have a voltage between 13 and 14 volts when the engine is
running. If not, there is a problem in the service battery
charging circuit ·Troubleshoot the service battery charging
circuit by checking the wiring and connections, the solenoid,
isolator, battery switch, and the battery itself.
When the problem bas been solved and before the alternator
is back in operation, take the time to tighten and clean the
tenninal studs. Also clean the connecting terminals
from
the
wiring hamess.
ALTERNATOR REPAIR
If tests indicate a failed alternator, it will need to be disas-
sembled and repaired. Any good alternator service shop can
do the job.
NOTE:
WESTERBEKE'S Service MaJluallws detailed
instructions for the disassembly and repair of their"
standard altemlltors.
BATTERY CARE
The minimum recommended capacity of the battery used in
the engine's 12 volt DC control circuit is 600 - 900 Cold
<::ranking Amps (CCA).
Review the manufacturer's recommendations and then
estabJisb·a systematic maintenance schedule for your
engine's starting batteries and house batteries.
• Monitor your voltmeter for proper charging dudng
engine operation.
• Check the electrolyte level and specific gravity with a
hydrometer.
• USe.
only distilled
w;;Ier
to bring electrolytes to a proper
level.
• Make
certmn
that "battery cable connections are clean and
tight to
the
battery posts (and
to
your engine).
TESTING THE
EXCITATION
CIRCUIT
ENGINE
RUNNING
EXCITER
TERMINAL
R
"
"
Engines & Generators
56
)