Generator not charging

[donQ]

I have a model A generator that won't charge, but will run as a motor on the bench. I suspect that the generator does not have enough residual magnetism to start the charging process. If lack of residual magnetism is the problem, how is it corrected? If residual magnetism is not the problem, what is likely to be wrong?

[30 Closed Cab PU]

Have you tried polarizing the generator?


Must have a cutout (not a regulator) on the generator, in a vehicle not running. Short across the cutout for 1 second. Just as a try, swap in a different cutout.


That is the extent of my knowledge, you could try searching here on the Barn, or wait for suggestions from others.

[donQ]

Thanks for the note. I have an instrumented fixture with a motor and a cutout. I'm measuring any voltage generated at the generator terminal. I have polarized the generator with the Motor not running.

[eagle]

Motoring the generator will polarize it.

[katy]

Originally Posted by eagle

Motoring the generator will polarize it.

Ditto

I have an instrumented fixture with a motor and a cutout.

What speed is the generator turning at? If'n it's turning too slow it won't generate.

[Badpuppy]

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Read voltage at the armature post. Cutout won't operate below 6.3V.

Edit - Re-read post #3. Guess you're doing that.

[donQ]

Katy,
I don't have a tachometer on my generator fixture, but the rpm is sufficient to allow model A generators to work. I have used this fixture for over 20 years and have used it to test many generators and used it to adjust the charging rate by moving the 3rd brush.
Don

[30 Closed Cab PU]

Perhaps compare winding resistances to a known good generator? Or swap out the armature with a known good armature?


The commutator plugged with brush dust/debris?


I do not know how you could measure the strength of the magnets.

[30 Closed Cab PU]

Did a search found this, not sure wha tit all means, perhaps it will help.


https://www.fordbarn.com/forum/showt...nerator+repair

[30 Closed Cab PU]

More info, check out last of the string by Tom.

[30 Closed Cab PU]

here is the post, forgot to include


https://www.fordbarn.com/forum/showt...nerator+repair

[donQ]

30 closed cab PU- Thanks for the note. I've copied some of the info in the posts you referenced. Also Katy wondered what rpm I run on my fixture. By taking the motor data from My GE fixture motor and measuring the diameters of the pulleys on the motor and the generator, I calculate the generator is turning at ~1146 rpm.
Don

[Tom Wesenberg]

500 engine RPM equals 750 generator RPM, which is about where the generator starts putting out enough to charge the battery, so 1146 RPM is plenty for good output.

[ryanheacox]

Would measuring the current it takes to motor tell anything?

[Keith True]

Did anybody work on this generator recently? Years ago I picked up a few generators at a swap meet that had been redone,but wouldn't charge.The seller had a sign on them,defective rebuilts.I bought them all. On those 3 brush generators there is a way to hook up a field wire wrong,and it will motor but won't charge.Tom W explained just what was wrong,that was the problem.I showed my generator guy,he said,yep,done that before myself a few times over the years.