Electrical System
36
24 690 37 Rev. B
KohlerEngines.com
15/20/25 Amp Battery Charging Systems
NOTE: Always zero ohmmeter on each scale before testing to ensure accurate readings. Voltage tests should be
made with engine running at 3600 RPM with no load. Battery must be good and fully charged.
When problems occur in keeping battery charged or battery charges at high rate, charging system or battery might be
causing problems.
To test charging system for no charge to battery:
1. Insert an ammeter in B+ lead from rectifier-regulator.
With engine running at 3600 RPM and B+ (at
terminal on rectifier-regulator) to ground using a DC
voltmeter.
If voltage is 13.8 volts or more, place a minimum
load of 5 amps (turn on lights if 60 watts or more, or
place a 2.5 ohm, 100 watt resistor across battery
terminals) on battery to reduce voltage. Observe
ammeter.
Condition
Conclusion
Charge rate increases
when load is applied.
Charging system is OK
and battery was fully
charged.
Charge rate does not
increase when load is
applied.
Test stator and rectifier-
regulator (steps 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.
Condition
Conclusion
Voltage is 28 volts or
more.
Stator is OK. Rectifier-
regulator is faulty; replace.
Voltage is less than 28
volts.
Stator is faulty; replace.
Test stator further using an
ohmmeter (steps 3 and 4).
3. With engine stopped, measure resistance across
stator leads using an ohmmeter.
Condition
Conclusion
Resistance is 0.1/0.2
ohms.
Stator is OK.
Resistance is 0 ohms.
Stator is shorted; replace.
Resistance is infinity
ohms.
Stator is open; replace.
4. With engine stopped, measure resistance from each
stator lead to ground using an ohmmeter.
Condition
Conclusion
Resistance is infinity ohms
(no continuity).
Stator is OK (not shorted
to ground).
Resistance (or continuity)
measured.
Stator leads are shorted to
ground; replace.
To test charging system for battery continuously charging
at high rate:
1. With engine running at 3600 RPM, measure voltage
from B+ lead to ground using a DC voltmeter.
Condition
Conclusion
Voltage is 14.7 volts or
less.
Charging system is OK.
Battery is unable to hold
charge; service or replace.
Voltage is more than 14.7
volts.
Faulty rectifier-regulator;
replace.
