Battery Light On

[glenn john deere]

Hello, I have a JD 332 that has had a battery light that has been coming on for a year. First it was bim and on at an idol. Now it is bright and on all the time.

I have checked the alternator and at an idol it regestered 17.8 AC volts. I replaced the battery that was 5 or 6 years old thinking there may have been a bad cell or two.......... The light is still on, any sugestions?

 

[stuckinnj]

AC Volts? You need to be measuring DC Volts. Charging system should put out about 13.8 - 14.5v DC if charging correctly. 1st check the basics - is your ground cable clean & tight from the battery to frame and engine to frame. Then check the positive battery cable from starter/alternator to battery. Perform a voltage drop test to confirm connections and cables are in good condition. You've taken a failed battery out of the test as you state you replaced it. The battery/alternator light typically will illuminate if the voltage is less then 12v DC.

What happens when you full throttle? Is this an idle issue only? Watch the voltage when you turn on the headlamps. A dramatic drop (>1.5V) would indicate a charging issue if you have already determined cable & connections are good.

That's my 2 cents.

 

[glenn john deere]

Thanks for the reply stuckinnj.

I have already determined that there is a problem in the charging system, I am trying to isolate the problem. I suspect that the voltage regulator is the problem as when I disconect the alternator and probe accross the two terminals in the pigtail coming out of the alternator I get 17.4 AC volts at an idol and 39.5 AC volts at the high RPM. At the battery I get 12.3 volts DC with the tractor running or not.

I get it that this is a 12 volt DC system. I was taking a tecks sugestion for trouble shooting the problem with the AC thing.

The battery light is still on and there is someone home trying to buy only the part that is defective. Trying to confirm that the regulator is bad.

Thanks

 

[crazyal]

I would say 99% chance that you're right, it's the regulator. Some of those regulators are not designed to run without a battery connected to them. Another check would be with the ignition turned on but the engine not running check to see if you have 12 volts at the regulator on one of the wires, if not maybe you have a broken wire somewhere.