Westerbeke W-46 - Alternator and Regulator Service; Alternator Description and Troubleshooting; Testing Alternator Charging Voltage

ALTERNATOR/REGULATOR SERVICE
DESCRIPTION
The alternator serves to keep the battery constantly charged.
It is driven from the pulley at the end of the crankshaft by a
V-belt. The type of alternator used is ideal for high speed
engines having a wide
range of engine speeds. It contains
diodes that convert AC to DC, and an JC regulator that keeps
the generated voltage constant even when the engine speed
changes.
A CAUDON: Do not DSe any hlgh·voltage tester such
as a megg111. Bthiii'Wise, damage to diodes will result.
During high-speed running of the engine. do not dlscon·
nect the PDSitlve or negati1111 tennlnal of the baltery
from terminal B of the altemator. II this Is done, diode
failure will teSIIII.
With altematotS hafling IC tegulatotS, absolutely avoid
a short cimllit between lelminals Band L. This would
allow current to flow in the 'lliDIIe trio
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and damage it.
Do not start the engine with the lead disDDnnected from
terminal B of the alternator. Otherwise, damage to the
roltage regulator wiiii'IJSII/1.
When charging the battery with a quit:k charger, be
sure to disconnect the battery tenninals to prevent
damage to diodes.
NOTE: The alternator connections and color coding described
on the following illustrations may vary from earlier WEST-
ERBEK.E engines. Always refer to the wiring diagrams in
this manual and also make a quick sketch of your alternator
wiring before
disconnecting for service.
ALTERNATOR TROUBLESHOOnNG
If you suspect that the alternator is not producing enough .
voltage
to charge the engine's battery, check the following:
0 Make certain your alternator is securely mounted.
0 Check the drive belts for proper tension.
0 Inspect for loose or disconnected wires at the alternator
A WARNING: A failed altel'llafor can become very
hot. Do not touch until the alternator has t:DDied down.
Testing The Charging Voltage
SHAFT If you suspect the alternator has failed, perform the following
tests.
SUP
RING
1. Using a voltmeter, connect the voltmeter red wire clip to
the output terminal B.
2. Connect the other voltmeter wire to any ground on the
engine.
3.
Start the engine and record the voltmeter's readings.
A CAUnON: To avoid damage to the battery charg·
lng circuit, never shut o" the engine battery switch
when the engine is running!
Engines & Generators
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