Battery Charging System - Onan NHC Series Operator's/Service Manual And Parts Catalog

BATTERY CHARGING SYSTEM
BATTERY CHARGING, FLYWHEEL
ALTERNATORS
The flywheel alternator is a permanent magnet alter-
natorand uses asolid-state voltage regulator-rectifier
for controlling output.
Two different alternator systems are used with NHC
and NHCV engines. One is a 20 amp Synch ro system,;
the other is a 15 amp Phelon system.
A 30-ampere fuse is included in the battery charging
system to protect the alternator in case the battery
cables are accidently reversed. Replace the fuse with
Onan Fuse 321-0162, Buss AGC30 or equivalent.
Weak ignition spark or a discharged battery indicate
trouble in the charging system. But before testing the
engine's charging system, always check the battery
for serviceability.
TESTING OR SERVICING
Keep these points in mind when testing or servicing
the flywheel alternator:
1. Be sure output control plug (connector) is in-
serted properly. Plug must bottom in receptacle-
eliminates any resistance due to a poor connec-
• tion. Keep clean'and tight. •
2. Make sure alternator stator leads are not shorted
together.
3. Be sure regulator-rectifier output control has a
good ground connection. Mating surface for
mounting must be clean and fasteners tightened
properly.
4. Never reverse the battery leads.
Charging system tests require a fully charged battery.
20 AMP SYNCHRO SYSTEM
The 20 amp flywheel alternator systems use a
separate regulator and a separate rectifier, Figure 28.
Testing: For testing this system, use a voltmeter-
ohmmeter such as a Simpson"27.0. Various alternator
problems with individual test procedures are listed in
t a b l e 2.
/
No Output—Stator Assembly: Examine leadwires for
loose or broken connections at the regulator and
rectifier. Use the Rxl scale on the ohmmeter for
detecting opens in the stator. Disconnect-.the three
wires that come from alternator stator (two black, one
red). Connect ohmmeter test leads to red leadwire
and ground to check continuity. The ohmmeter
reading should be about 2.0 ohms. See Figure 29 for
wiring diagram. •
Next, connect meter to black leadwires and ground.
Approximately 0.1 ohm should be read from either
black lead to ground. If no connection exists between
ground and black leads, stator assembly should be
replaced.
RECTIFIER
STATOR ASSY.
SCREEN B O L T
TIMING H O L E
THROUGH
F L Y W H E E L
F L Y W H E E L ON
PRESSURE COOLE
ENGINE
A L T E R N A T O R ROTOR
(PART OF F L Y W H E E L ASSY.)
FIGURE 28. 20 AMP SYSTEM
21