Onan NHC Series Operator's/Service Manual And Parts Catalog page 171

NOTE: Poor contact at the battery cable con-
nections is often a source of trouble. Make sure
battery cables are in good condition and that
contacting surfaces are clean and tightly con-
nected. Do not reverse battery leads. Use recom-
mended battery tools when disconnecting leads to
avoid mechanical battery damagel
2. Make sure the two alternator stator leads are not
shorted together.
3. Check mounting of regulator-rectifier case to unit.
It should provide a good electrical ground with
clean, bright surfaces.
4. Output control plug (connector) must be pushed in
so . i t bottoms solidly in the receptacle. Keep it
clean ahd tight.
IMPORTANT: Charging system tests require a
fully charged battery.
Testing: With the engine running between' 1800-2600
rpm, observe the panel ammeter, (if not already
equipped, connect a test ammeter.) If no charging is
evident, proceed with the NO CHARGE TEST given
as follows. If ammeter shows a constant higher charge
rate, follow the HIGH CHARGE RATE TEST procedure.
No Charge Test: Perform as follows:
1. Check the B+ to ground voltage using a DC
voltmeter.
2. If voltmeter reads 13.8volts or higher, add a load
to system (e.g. headlights) to reduce battery
voltage to below 13.6 volts.
3. Observe ammeter. If charge rate increases, consi-
der the system as satisfactory. If charge rate does
not increase, proceed with testing.
4. Disconnect, plug from regulator-rectifier and test
the AC voltage at the plug with engine running
near 3600 rpm. If AC voltage reads less than
28 Volts, replace the stator. If AC voltage is more
than 28 volts, replace the regulator-rectifier assem-
bly.
High Charging Rate Test: Perform this test as f o l l o w s :
1. Check B+ to ground voltage with a DC voltmeter.
2. If voltmeter reads over 14.7 volts, replace regulator-
rectifier assembly.
3. If reading is under 14.7 volts the system is proba-
bly okay. Recheck the battery.and connections. If
the battery does , have a low charge, but accepts
recharging, system is okay.
A L T E R N A T O R R O T O R
( P A R T O F F L Y W H E E L A S S E M B L Y )
S T A T O R
R E G U L A T O R - R E C T I F I E R
FIGURE 25. FLYWHEEL ALTERNATOR t N Q, V f T> M. Vfr- l/lf 14/
25