gen losing magnetism

boler76 · Oct 23, 2018

this is an original 6v pos grd gen with a cutout, when first started there is no output until flashed by hand, then everything works as it should for numerous starts and stops but when left stopped for a couple days, the same scenario has to be repeated, what is the remedy that I don't know about? Thanks

gene bender · Oct 23, 2018

Why not get the gen serviced just mite need new brushes and the commutator cleaned. Those gens do very well if in shape.

Janicholson · Oct 23, 2018

My best guess. If the magnetism weakens a little in a week that would be pretty normal. It is after all, just iron, not a permanent "alloy" magnet. If the cutout relay is set to pull in at 1 volt over battery volts, and the generator puts out that with no closed cutout, the cutout will close and provide charge. if the cutout air gap or spring tension is 2 volts over bat voltage, and the gen puts out 1.6 volts over bat volts, the cutout will not close, and it won't charge. Then flashing it causes the magnetism to be stronger than it was, and the gen puts out 2.2 volts, and the relay latches, and charges.
Were it mine I would either close the gap on the cutout (Disconnected from the battery terminal) by a few thousandths, or incrementally decrease the spring pressure holding the points open. Closing the points just a little is far more likely to be a finer adjustment, and not screw up the opening of the points when gen output is lower than battery volts. (Idling with the lights on or as it stops when shut off. Jim

Bob · Oct 23, 2018

(quoted from post at 19:19:11 10/23/18) Why not get the gen serviced just mite need new brushes and the commutator cleaned. Those gens do very well if in shape.

Gotta agree with Gene here.

A generator with no issues can sit unused for YEARS and still "excite" at startup.

Usually, "Jim" is "spot on" but I can't agree with his post that generators may lose the ability to self-excite and begin charging after only a few days.

And I don't agree with "tweaking" the cutout, IF it's working when the generator DOES self-excite at at startup.

There's a VERY fine line between the cutout closing when the generator has self-excited and needs to be connected to the battery, and also OPENING when it needs to to prevent discharging the battery and letting the $$$smoke out of the generator and cutout.

sotxbill · Oct 23, 2018

as others said.. gennys dont loose magatisum... SO>>>>

either your brushes are bad, your ground it bad, your cutout relay is bad, or your cables are bad.

Flashing it just makes it go to full voltage momentarily to overcome the problem elsewhere....

I would guess again, bad cut out relay, high resistance connection to the cut out relay, or to battery, or bad/arcing brushes not making good contact with the armature. The soft iron in the "shoes" of the field will hold a charge for many years with out being used.

flashing just raises the voltage to max,,,,, to overcome the problem elsewhere. have you checked the contacts on the cutout relay?? are they dirty or carboned up? are the leads corroded? I have even seen a bad ground where the genny bolts to the tractor, and loosening and tightening the bolts fixed the ground problem..

HTH.

Steve@Advance · Oct 23, 2018

Jim, have you ever tried an electronic cutout? I never have, but looks like a good idea.

Wondering if that might be a solution here.

boler76 · Oct 24, 2018

thanks for all the input, I will be self fixing it with the knowledge gained here ,

Hendrik · Oct 24, 2018

What did you do for "flashing"?
Ground the field of the generator OR polarize the generator?

dr sportster · Oct 24, 2018

The residual magnetism is stored in the iron housing. Years ago a company made aluminum housings for a Sportster generator -- problem was they did not work.

boler76 · Oct 24, 2018

grounding the field did not work,

Janicholson · Oct 25, 2018

Yes. I just put a 40 amp diode where it used to be, no problem. Jim

gen losing magnetism

boler76

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gene bender

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Janicholson

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Bob

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sotxbill

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Steve@Advance

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boler76

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Hendrik

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dr sportster

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boler76

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Janicholson

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