Testing a generator with a voltmeter

[JSkolits]

I justy installed a new generator and want to make sure it works. I polarized the generator as explained by the parts company. (hopefully I did it right)

So how I can I check to make sure the generator is working? With car alternators, I simply measure the voltage across the battery to make sure it's 12V with the engine not running and 13+ V when it is. But I tried the same with the tractor and it seems I get 6 Volts when not running and then "0" volts when running. That seems awfully odd. I tried both DC and AC setting on my voltmeter.

 

[Dean]

JS:

There is nothing wrong with your technique but something is obviously wrong with the results.

You cannot measure 0 volts across a charged 6 volt battery without a fire and/or explosion.

Are you using an analog meter? If not your digital meter may default to a 0 volt reading when it cannot respond to the varying voltage produced by your generator.

Dean

 

[Anonymous-0]

I just did a retest. I guess the leads fell off when I did my initial test.

Turns out the voltage was 6.1 VDC with it off and dropped every so slighlty to 6.0 volts when I stared it. Not a signifcant change. The battery is only a few months old and I've only run the tractor for about 10 hours on it.

Do you think the generator it's working?

 

[RodinNS]

No, it's not charging. It should make 6.5+ V when it's running. IF you don't see an increase in battery voltage when the tractor is running, you have a charging problem.

Rod

 

[JSkolits]

Hmmm... Well, I'll take another look at it tomorrow. The last generator burned out big time. I wonder if a wiring problem caused that. Thanks for the response, you may hear from me again.

John

 

[awhtx]

Maybe your parts man didn't realize that you were dealing with a positive ground electrical system and told you something wrong.
Soundguy will be along soon to explain the difference in polarizing + and - ground systems.

 

[Anonymous-0]

7.3 to 7.5 volts when charging.

 

[souNdguy]

Sp what kind of a tractor are we working on here? a 9n, 8n, naa, hundred series? thousand series? non ford product?? makes a difference as to the answer.

If your meter is a digital.. it will be virtually useless to check a genny output.

I like using a headlamp as a load device.. I clip one terminal tot he armature, and the other to ground, and then start her up, with the vr connected.. etc.

What did you do to polarize?

8n's are a-circuit, and polarize by jumping arm and bat.

naa+ are b-circuit and poalrize bu jumping field and bat.

Have you tried a motor test?

slip belt off, disconnect vr completely, and hook bat to arm.

if a-citcuit, then ground field.

if b-circuit then hook field to arm.

Genny should motor over ( spin)

most gennies that motor, will charge.. most gennies that charge, will motor.

soundguy