Need to check my thinking

old · May 19, 2012

If an amp gauge goes bad can it keep the charging system form charging the battery??? My Oliver S88 is a 12 volt system and the amp gauge seems to have stopped working and from other things makes me think the alternator is not charging the battery and all I can see that might be wrong is the amp gauge. New alternator by the way

mnbob · May 19, 2012

(quoted from post at 10:57:17 05/19/12) If an amp gauge goes bad can it keep the charging system form charging the battery??? My Oliver S88 is a 12 volt system and the amp gauge seems to have stopped working and from other things makes me think the alternator is not charging the battery and all I can see that might be wrong is the amp gauge. New alternator by the way

check that "new" alternator, wouldnt be the first time one went south. May not be the gauge. unless the gauge is shorting to ground dont know how it would prevent charging.

retired farmer · May 19, 2012

Did you check to see if the alternator was putting out? Could be bad, have had that happen more than once. New parts don't mean they actually work when installed.

fixerupper · May 19, 2012

I suppose an ammeter could lose continuity. I don't really know the answer. Check your voltage, if not within specs, jump around the ammeter and check again. I know the back of the ammeter isn't the easiest to get to with the battery in there. Jim

old · May 19, 2012

Found the problem. Alternator is good but the wire from the big post to the gauge had gone bad so no power to or from the alternator so it did not work. Replaced the bad wire and the gauge jumped to 20 amp charge and every thing worked as it should now. Took a bit of trouble shooting to figure it out but since it had 9 or so volt when running and zero volts at the alternator big post was not all that hard to trace what was wrong

Keith Williams · May 19, 2012

Old,
If it is open, then there would be no way for the current to get thru. Put a jumper across the posts to bypass the gauge.
Keith

MarkB_MI · May 19, 2012

By "not working", I assume you mean it shows neither charge nor discharge. Your ammeter may not be bad, but lack of indication could be a symptom of the real problem.

Ammeters work by measuring voltage across a shunt. The shunt may be part of the meter, or (typical in autos) it can be remote from the meter. If you have heavy gauge wires going to the meter, the shunt is part of the meter. It the meter movement blows, the shunt will continue to pass current. It's unusual for a shunt to fail (they'll take at least 100 amps), but it's not uncommon for the shunt wiring to break. Also, there's often a fuse or fusible line inline with the shunt. Follow the heavy gauge wires from the gauge back to wherever they go, you'll probably find the problem.

fixerupper · May 19, 2012

Glad to hear you found it. When I get home, there are a couple of new front tires waiting to be put on my 88. They have been looking very bad since I don't remember when but I told everbody who looked at them I wasn't replacing them until one went flat. My luck ran out. Frayed cord rubbed through the tube. New ones are $125 APIECE!!! Plus tubes. 5.50X16 three rib. Jim

old · May 19, 2012

Yep know about the tire thing. Years ago I was told I needed new tires on my A/C W Speed Patrol rears and I have yet to replace them but I also do have a good set sitting in the back of the shed for when the old tires do pop. That was more then 15 years ago when some one told me that

John B. · May 19, 2012

The 2 posts/wires on the amp meter should have power to them at all times. If only one has power it's bad. If neither of them has power turn your key on and check them both.

mkirsch · May 19, 2012

If it's a gasser, the ignition power runs through the ammeter. If the tractor runs then the alternator should charge.

old · May 20, 2012

It runs and yes it should be charging but it was not due to a bad wire going from the alternator big post up to the amp gauge so no power to the alternator or out of it. Replaced that wire and all is fine now

Need to check my thinking

old

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mnbob

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retired farmer

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fixerupper

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old

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Keith Williams

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MarkB_MI

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fixerupper

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old

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John B.

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