Alternator/voltage regulator

[luvmexfood]

Have an old Universal tractor that started to not turn over. Battery is about 2.5 years old. Checked battery voltage with tractor off and would have about 9 volts. With tractor running and varying RPMS I get 12.8 volts at the battery, starter and alternator output. The alternator has an external voltage regulator.

Any idea of weather it would be the alternator or voltage regulator?

 

[banjodunn]

G'day if you have 9v not running and 12.8 running then there is nothing wrong with your charging system it is either a battery fault or a power drain somewhere discharging the battery.


Jon

 

[Gordon Gould]

Put your V meter across the Battery with the tractor running then turn off the tractor. If the 12.8 V immediately drops to 9 V I would guess you might have a shorted cell in the Battery.

 

[Zebrafive]

Sounds like a bad battery and the regulator bases the alternator output on the battery voltage (9volts) that it sees. If your battery was at 12 volts, I think the alternator output would be higher.