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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
regulator is very compact and is mounted internally or on the
back of 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
inc~easing
toward 14 volts.
If
it is,
the
alternator is working.
Turn
to Step
4
( 14.0)
o
COM
,
MULTIMETER
~iS===:::
#10 RED
. TO STARTER SOLENOID
#14 VIOLET
TO CHOKE
TROUBLESHOOTING
I·
A
WARNING:
A failed alternator can become very
hot. 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 iso-
late the batteries so the service battery is not discharged along
with the service battery. If the alternator is charging the start-
ing battery but not the service battery,. the problem is in the
service battery charging circuit and not with the alternator.
Testing 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:
MULT/METERS 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 pedorming DC testing. No AC tests should be
made without proper knowledge of AC circuits.
TESTING THE STARTING
BATTERY· ALTERNATOR
(ENGINE RUNNING)
_
GROUND
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.
Thrn
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.
TESTING THE
ALTERNATOR VOLTAGE·
(IGNITION ON - ENGINE OFF)
(g])
0~_-.MULTIMETER
COM
+
;a
Engines & Generators
-=-
GROUND
22
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Table of Contents
Troubleshooting
