Genny not charging

fixerupper · Aug 10, 2018

Generator off a 630 Deere pos ground quit charging. It's a rebuilt from Deere I put on maybe 7 years ago or more. It will motor but it will not charge with the field grounded. I ran a ground jumper from the regulator frame to a good ground on the tractor frame and I ran a ground from the genny frame to good tractor frame ground but that didn't change anything. I pulled off the end cap and this is what I saw. It's not very clear, the top bar on the commutator has a burned spot in the middle. The brushes have not been making good contact across the commutator. All in all there is not a lot of wear but it looks to me like the rebuild job was done pretty fast and incomplete. Is this genny junk or is there some salvation in it? I could turn the commutator in a lathe to true it up but I don't think that will help me out.

55 50 Ron · Aug 10, 2018

Does it get a lot of use? 7 years is probably time to do a new set of brushes and shine the commutator as a minimum. Seems if it motors it should charge, but I suppose there are exceptions. Brushes will be a low cost first try to get it working.

fixerupper · Aug 10, 2018

It does not get a lot of use anymore. Maybe 20 hours per year tops. The brushes are good and long yet, nothing wrong with them. The lack of a flat surface on the commutator will just reduce the maximum output capability. It's that burned spot that concerns me and the fact that grounding the field does not make it charge.

bigbob1939 · Aug 10, 2018

Check bad looking commutator bar to shaft with multi meter for short. Check good. Turn down commutator, clean out just a little insulation between bars with hack saw blade, replace brushes, should work like new.

JMOR · Aug 10, 2018

That commutator, while not perfect, is not likely to be the problem. They will motor on residual. Stick an ammeter between gen FIELD terminal and ground and while running, measure field current. It should be around 2 amperes, if significantly higher or lower, the field coils are your problem. Also, when motoring it, the rotational speed should be noticeably lower with field grounded that open.

Ted in NE-OH · Aug 10, 2018

Check cutout relay

David G · Aug 10, 2018

I am near Cedar Rapids, can clean the commutator up if you want.

rvirgil_KS · Aug 11, 2018

X 2

Grounding the field terminal on generator only bypasses the regulator side of the voltage regulator. An open cutout in the regulator will not connect charge current to battery.

Ground field, if it now charges it indicates bad regulator side. If still no charge jumper armature to BAT on regulator. If it now charges suspect bad cut out. If still no charge you have bypassed regulator so suspect generator problem.

Genny not charging

fixerupper

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55 50 Ron

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fixerupper

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bigbob1939

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JMOR

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Ted in NE-OH

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David G

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rvirgil_KS

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