How to see if a genertor is working?

Hi guys-In the past, I have checked to see if a generator is working by hooking up a volt meter to the battery and see if the voltage increases with the tractor running.

Is this a valid way to check one on a tractor?

Like you hear your thoughts....thanks.

There's a reason Allis-Chalmers had an ammeter on the tractor.......it tells you if the charging system is working or not.

Start the tractor then unhook the battery. If generator is working it will keep running, this won't work if you have a mag.

ctbowles 58 wrote: Ground the Field (F) post on the Generator to the frame of the tractor, if it charges on the gauge then your Gen. is ok  if not then the Gen. is bad. Works every time. If the amp gauge shows a charge after grounding the field then check the cutout or regulator. 0

DougS that BAT terminal is NOT on the generator, its on the regulator.

An ammeter test is fairly easy. Before starting the engine turn on the ignition and the lights and if the points are closed and the lights aren't run from an L terminal on the regulator the ammeter will show a discharge. Then if it shows charge when the engine is running at a fast idle the generator is working. A generator generally does not charge at engine idle. If the voltage regulator is regulating well, the charging current will taper in time, depending on the generator current capability, down to zero current. It may take hours of running. Ammeters have been known to fail from rusty pivots. The meter movement is not high horsepower or torque.

Gerald J.

I should have clarified. This is a 1935 M crawler that I have converted to 12 v using a starter/generator off of a lawnmower (has to use this as it spins opposite of most generators). I think I have it wired correct and think I have the correct voltage regulator on it...but to prove it I will run the test you guys suggested.   Thanks.

Grounding the F terminal while running is a quick test. If it wasn't working but works this way investigate the F circuit between the generator and regulator.
For the sake of discussion I'm going to assume negative ground.
To test a generator remove the belt and unhook the F terminal on the generator. Using a heavy run battery positive to the A terminal on the generator. It should spin fast like a motor. While motoring ground the F terminal. It should slow down but continue to motor. if these tests pass, time to test the wires. Using a headlight bulb, use each wire in a circuit to light the bulb. Bright light = good wire. If the wires test good, test the battery terminal wire with the bulb. Bright light = good. If it still doesn't work, make sure the regulator has a clean ground. Buff off any paint or rust making sure there is a good electrical connection back to the battery negative. Still doesn't work, replace the regulator.
With any generator you should polarize it before starting the engine. When you do the motor test it is polarized at that time. If you install a reman or otherwise unknown unit, a momentary jump between the battery terminal and A terminal at the regulator does the job.