Atlernator Testing - Westerbeke 12C-TWO Operator's Manual

ALTERNATOR TESTING
DESCRIPTION
The charging system consists of an alternator with a voltage
regulator, an engine DC wiring harness, a mounted DC cir-
cuit breaker and a battery with connecting cables. Because of
the use of integrated circuits (IC's) the electronic voltage reg-
ulator is very compact and is mounted internally or on the
back of the alternator.
#10 RED
CURRENT MODEL
50 AMP
ALTERNATOR
Testing the Alternator
1. Start the Engine.
2. After a few minutes of running measure the starting bat-
tery voltage at the battery terminals using a multi-meter
set on DC volts.
The voltage should be increasing toward 14 volts. If it is,
the alternator is working. Tum to Step 4.
TESTING THE STARTING
BATTERY - ALTERNATOR
{ENGINE RUNNING)
MULTIMETER
#14 PURPLE
~~~~~~#10
RED
EARLY MODEL
35AMP
ALTERNATOR
=
GROUND
TROUBLESHOOTING
A
WARNING:
A failed alternator can become very
bot. Do not touch until the alternator has cooled down.
This troubleshooting section is to determine if a problem
exists with the charging circuit or with the alternator. If it is
determined that the alternator or voltage regulator is bad, it is
best to have a qualified technician check it out.
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 service 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 charging circuit and not with.the alternator.
A WARNING~
Before starting the engine make certain
that everyone is clear of moving parts! Keep away from
sheaves and belts during test procedures.
A
WARNING:
Multimeters and DC Circuits:
DC and AC circuits are often mixed together in marine
applications. Always disconnect shore power cords,
isolate DC and AC converters and shut down generators
before pertonning DC testing. No AC tests should be
made without proper knowledge of AC circuits.
37
B+ OUTPUT
To starter motor
3. If the starting battery voltage remains around 12 volts
after the engine is started and run for a few minutes, a
problem exists with the alternator or the charging circuit.
a. Turn 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!
b. If a battery selector switch is in the charging circuit,
ensure that it is on the correct setting.
c. Turn on the ignition switch, but do not start the engine.
d. Check the battery voltage. If your battery is in good
condition the reading should be 12 to 13 volts.
cmJ
0
TESTING THE
COM
ALTERNATOR VOLTAGE
{IGNITION ON - ENGINE OFF)
MULTIMffiR