Dc Electrical System; Alternator Troubleshooting - Westerbeke W35B Operator's Manual

DC ELECTRICAL SYSTEM
ALTERNATOR
The charging system consists of a DC belt driven alternator
with a voltage regulator, an engine DC\viring harness, 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.
~
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 tlu-ough 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 alternator or the charging circuit;
continue with Steps 3 through 8.
#10 RED BATTERY CONNECTOR
,AT STARTER
mm
MULTIMETER-~e
COM
51A ALTERNATOR
(SHOWN)
Refer to the WIRING DIAGRAMS IN
this manual for the alternator models
and their wiring connections.
112 BLACK TO
GROUND AT STARTER
ALTERNATOR TROUBLESHOOTING
A
WARNING:
A failed alternator can
be~ome
very
hot. Do.not touch until the alternator has cooled down.
Use this troubleshooting section to detennine 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 batte1ies so the staJ.ting 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 altema·
tor.
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.
A
WARNING:
When testing with a multimeter:
DC and 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 performing DC testing. No AC tests should.be
made without'a proper knowledge of AC circuits.
TESTING THE STARTING .
BATTERY/ALTERNATOR
(ENGINE RUNNING)
-::- GROUND
3.
Turn
off the engine. Inspect all wiring, and connections.
Ensure that the battery Lenninals and the engine ground
connections are tight and clean.
A
CAUTION:
To avoid damage to the battery
charging circuit, never shut oft the engine battery
switch when tlie 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 battery voltage. If the battery is in good condi-
tion, the reading should be 12 to 13 volts.
TESTING THE
ALTERNATOR VOLTAGE
(IGNITION ON - ENGINE OFF)
Engines & Generators
- 'GROUND
29