Dc Electrical System; Alternator; Alternator Troubleshooting - Westerbeke 10.0 EGTD Operator's Manual

DC ELECTRICAL SYSTEM
ALTERNATOR
The charging system consists of a DC belt driven alternator
with a voltage regulator, an engine DC wiring har.ness, a
mounted DC circuit breaker and a battery with connecting
cables. Because of the use of integrated circuits
(IC's),
the
electronic voltage regulator is very compact and is mounted
internally or on the back of the alternator.
#10 ORANGE
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 alterna-
tor is working; omit Steps 3 through 8 and go directly
to "Checking the Service Battery" on the next page.
b.
If the voltage remains around
12
volts, a problem
exists with either the altema,tor or the charging circuit;
continue with Steps 3 through 8.
START MOTOR SOLENOID
1114 VIOLET
TO FUEL SOLENOID.
· FUEL PUMP, AND
TO T82 {11
ALTERNATOR MOUNT (GROUND)
ALTERNATOR TROUBLESHOOTING
A
WARNING:
A failed alternator can become very
hot. Do not touch until the altemator has cooled down.
Use this troubleshooting section to determine if a problem
exists with the charging circuit or with the ·alternator.
If it is
detennined that the alternator or voltage regulator is faulty,
have a qualified technician check it.
The alternator charging circuit charges the starting battery
and the service battery. An isolator with
a
diode, a solenoid
or a battery selector switch
is
usually mounted in the circuit
to isolate the batteries so the starting battery is not discharged
along with the service battery. If the alternator is charging the
starting battery but not
the
service battery, the problem is in
the service battery's charging circuit and not with the alterna-
tor.
Testing the Alternator
A
CAUTION:
Before starting the engine make certain
that everyone is clear o! moving parts! Keep away from
sheaves and belts during test procedures.
A
WARNING:
When testing with a moltimeter:
DC 1nd AC circuits are often mixed together in marine
applications. Always disconnect a shore power cord,
isolate DC and AC converters, and shut down the engine
before perfonning DC testing. No AC tests should be
made without a proper knowledge of AC circuits.
21
MULTIMETER
TESnNG THE STARTING
BATTERY/ALTERNATOR
(ENGINE RUNNING)
3. Tum
off the engine .. Inspect
all
wiring and connections.
Ensure that the .battery terminals and the engine ground
connections are tight and
clean.
A
CAUTION:
To avoid damage to the battery
charging circuit, never shut off the engine battery
switch when the engine is running!
4. If a battery selector switch is in the charging circuit,
ensure that it is on the correct setting.
5. Tum
on the ignition switch, but do not
start
the engine.
6. Check the battecy voltage. If the battery is in good condi-
tion, the reading should be
12
to 13 volts.
TESnNG THE STARTING
BATTERY/· ENGINE OFF)
~
G
COM
+
-----MULTIMETER
-:GROUND