farmall 140 amp gauge

harley fatboy · Jun 21, 2019

I have a farmall 140 when running the amp gauge bounches from center to bottom on charge side after it has ran for some time it returns to the center but then discharges the battery the voltage reg. points are working took cover off both opening and closing and there is a spark on both had the gen. rebuilt need help any thing to try or what could cause this any help would be great thanks.

Steve@Advance · Jun 21, 2019

Welcome harley fatboy!

A really bouncy amp gauge is usually a result of a mechanically worn gauge (no big deal, will not effect the charging), and a not so good regulator.

Looking on the back side of a regulator, you will see a couple of wire wound resistors. Those are intended to level off some of the "indecisive" surging and arcing as the battery nears it's full charge level. There could be a problem with one of the resistors, could be the contacts are arcing and sticking. Even if it is a new regulator, all the new regulators are generic, fit all, close but not perfect, low grade alloy contacts, imported... Well, you get the picture.

One thing to check though, be sure the base is grounded. A common problem if the tractor was recently painted, the paint can insulate the base from ground.

Try connecting a volt meter across the battery while running, see if the meter agrees with the amp meter, as in intermittent charging.

When does the battery discharge? While running or when parked?

If the battery is being drained when parked, the cut-out relay portion of the regulator is not opening when the generator output stops.

harley fatboy · Jun 21, 2019

the battery starts to discharge while it is running will run the battery all the way so it will not start back if cut off it seams if you run it for about an hour or so it will take the battery down after a while the guage stops bounceing and stays at the stright up point or in the middle of the guage thanks for getting back

Janicholson · Jun 21, 2019

A sticking set of contacts in the cutout relay can do that. The cutout is intended to latch the generator into the charging circuit when it is charging more voltage than the battery. (charging) it is also set to disconnect if the charging voltage is less than the battery voltage. The voltage regulator part of the regulator is in control of the amount of charge, by regulating the amount of field current. This limits the max voltage and prevents over charging. It is connected to the field circuit as a grounding point. When full output is needed, the v regulator allows near full grounding of the field. the points in the v regulator vibrate to limit max voltage. Making and braking the field circuit. The Farmall tractors are intended to run at or near full RPM in use. Generators are designed to do just that. If you putter around, it will not do its job. John T has a charging system check list that helps. Jim

farmall 140 amp gauge

harley fatboy

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Steve@Advance

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harley fatboy

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Janicholson

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