Westerbeke 8.0KW-60Hz Service Manual page 40

DC ELECTRICAL SYSTEM
7. Now check the voltage between the alternator output ter·
minaJ
(B+)
and ground. If the circuit is good, the voltage at
the alternator will be the same
lis
the battery, or if an isola·
tor is in the circuit the alternator voltage will be zero. If
neither of the above is true, a problem exists in the circuit
between the alternator and the battery. Check all the
connections -look for an opening in the charging circuit
STARTING BATIERY
g9 (±)
g99Q .
TESTING THE STARTING
BATTERY/ALTERNATOR
(ENGINE RUNNING)
MUlTIMETER
(]2JD
G
OM
'.,..c:=--'
ENGINE
~ GROUND
8. Start the engine again. Check the voltage between the
alternator output and ground.
The voltage reading for a properly operating alternator
should be between
13.5
and
14.5
volts. If your alternator
is over- or under-charging, have it repaired at a reliable
service facility.
NOTE:
Before re1lWving the alternator for repair, use a
voltmeter to ensure that 12 volts
De
excitation is present
at the
EKe
tenninal
if
the previous test showed only bat-
tery voltage
at
the B output tenninal.
If
12 volts
is not present
at the
Exe
tenninal, trace the
wiring
and
look for breaks
and
poor connections.
12 VOLT DC CONmOL CIRCUIT
The engine has a
12
volt DC eleclrical control circuit that is
shown on the wiring diagrams that follow. Refer to these
diagrams when troubleshooting or when servicing the DC
eleclricaJ system.
A
CAUTION:
To avoid damage to the battery charging
circuit, never shut off the engine battery switch while
ths snglne Is mnnlng. Shut off the engine battery switch,
howsver, to avoid IIllIctrlcal shorts when working on the
IInglne's slsctrlcal circuit.
BATTERY
The
minimum
recommended capacity of the battery used in
the engine's
12
volt DC control circuit is
600 - 900
Cold
Cranking Amps (CCA). '
Checking the Service Battery
Check the voltage of the service battery. 1bis 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.
MULTIMETEB
I
COM
GROUND
,SERVICE BATIERY
TESTING THE SERVICE
BATTERY (ENGINE RUNNING)
A
CAUTION:
To avoid damaging the altemator diodes,
do not use a high voltage tester (I.s. a mllggsr) when
pedonnlng tests on ths alternator charging circuit.
Battery Care
Review the manufacturer's recommendations and then
establish a systematic maintenance schedule for your
engine's starting batteries and house batteries.
o
Monitor your voltmeter for proper charging during
engine operation.
o
Check the electrolyte level and specific gravity with a
hydrometer.
o
Use only distilled water to bring electrolytes to a proper
level.
o
Make certain that battery cable connections are clean and
tight to the battery posts (and to your engine).
o
Keep your batteries clean and
free
of corrosion.
A
WARNING:
Sulfuric acid In lead batteries can
cause sevllre bums on skin and damagll clothing. Wear
protective gear.
Englnes,& Generators
32