TE 20 Charging issue

I just had my 12 volt generator on my Ferguson TE 20-85 fixed and rebuilt. The amp gauge shows that it is working. However, when I run the tractor for 30 minutes or so, the battery runs down. This did not happen when the generator wasn't working (before rebuild). Anybody know what's going on here?
If you did not change any wiring, take the alt off and get it bench tested for output.
Then stuff it back on the machine and using a volt meter, check static battery voltage.
Should be 12.6 give or take.
Fire it up and voltage should rise to 13.8/15 volts.
If it does not rise, run a jumper wire from the case of the alt to battery ground.
Did it rise then?
Bad case ground. Too much paint.
Didn't rise?
Check that wiring.

He posted: ''I just had my 12 volt generator on my Ferguson TE 20-85 fixed and rebuilt.''

Is the battery hooked up positive or negative ground? Was it polarized to the tractor's ground? The shop may have polarized it to the opposite ground. What is the voltage at the battery when it is running? If the battery is hooked up backwards it could be discharging when the ammeter shows charge.
I was told the generator was polarized as positive ground and the battery is hooked up positive ground. When not running the battery is showing about 12.3 volts. When running, it drops to about 11.2 volts. The ammeter shows a positive charge so the charge is getting to the ammeter but not the battery. I will have to retrace my wiring. If the generator was mistakenly polarized negative ground would it cause this?

How do you know a positive charge is getting to the ammeter?
What voltage do you see at the battery terminal of the regulator? What is the voltage at both terminals of the Ammeter? Did you have the regulator set up and tested with the generator? If the ground is wrong or the ammeter terminals have the wrong wires on them it can show charge when it is actually discharging.

Double check your wiring, just to be sure.
If the lights come on it should show minus or negative.
Just turn the key on and if the points are closed it should also show minus or negative maybe 2 amps or so. From the factory I believe yours should be positive earth or ground.
That does not mean it stayed that way. If your coil is marked, does the + plus side go to the distributor. It will run hooked up backwards but not as good as it can if hooked up properly.
Thanks, I never thought about the coil. I'll check these things out. My Ferguson has not had a working generator for many years. Always just kept the battery charged. I decided this year to fix it. The voltage regulator was new about 15 years ago but because the generator was bad it was never operational. I hope it's still OK. I never polarized anytime. The shop that fixed my generator said they positive ground polarized it but I did not polarize it in the tractor with the voltage regulator. I'll give that a try.

The regulator may be bad. Just because it was new 15 years ago means nothing. Can the shop that did your generator run the generator and regulator together on their test bench and check operation of both? If you take the wires off the regulator tag the wires as to which terminal they are connected to.
Wiring Schematic...


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