7.10
Section 7
Electrical System and Components
Troubleshooting Guide
15/20/25 Amp Battery Charging Systems
When problems occur in keeping the battery charged or the battery charges at too high a rate, the problem can
usually be found somewhere in the charging system or with the battery.
NOTE: Always zero ohmmeter on each scale before testing
to ensure accurate readings. Voltage tests should
be made with the engine running at 3600 RPM - no load.
The battery must be good and fully charged.
Problem
Test
Conclusion
1. Trace B+ lead from rectifier-regulator to key
switch, or other accessible connection.
Disconnect it from switch or connection.
Connect an ammeter from loose end of B+
lead to positive terminal of battery. Connect
DC voltmeter from loose end of B+ lead to
negative terminal of battery. With engine
running at 3600 RPM, read voltage on
voltmeter.
If voltage is 13.8 volts or more, place a
minimum load of 5 amps* on battery to
reduce voltage. Observe ammeter.
*
NOTE
: Turn on lights, if 60 watts or more.
Or place a 2.5 ohm, 100 watt
resistor across battery terminals.
1. If voltage is 13.8-14.7 and charge rate
increases when load is applied, the charging
system is OK and battery was fully charged.
If voltage is less than 13.8 or charge rate
does not increase when load is applied, test
stator (Tests 2 and 3).
2. Remove connector from rectifier-regulator.
With engine running at 3600 RPM, measure
AC voltage across stator leads using an AC
voltmeter.
2. If voltage is
28 volts or more,
stator is OK.
Rectifier-regulator is faulty. Replace the
rectifier-regulator.
If voltage is
less than 28 volts,
stator is
probably faulty and should be replaced. Test
stator further using an ohmmeter (Test 3).
No Charge
to Battery
3a. With engine stopped, measure the
resistance across stator leads using an
ohmmeter.
3a. If resistance is
0.064/0.2 ohms,
the stator is
OK.
If the resistance is
infinity ohms,
stator is
open. Replace stator.
3b. With the engine stopped, measure the
resistance from each stator lead to ground
using an ohmmeter.
3b. If the resistance is
infinity ohms
(no
continuity), the stator is OK (not shorted to
ground).
If resistance (or continuity)
is measured,
the
stator leads are shorted to ground. Replace
stator.
1. If the voltage is
14.7 volts or less
the charging
system is OK. The battery is unable to hold a
charge. Service battery or replace as
necessary.
If voltage is
more than 14.7 volts,
the rectifier-
regulator is faulty. Replace rectifier-regulator.
1. Perform same test as step 1 above.
Battery
Continuously
Charges at
High Rate
