Alternator Confusion, Positive Ground

[2SteveWI]

Thanks for all the feedback, especially appreciated for someone who joined today and has not contributed to community yet.

Just to clarify, the positive terminal of the battery is connected to the frame of the tractor.

If I believe my neighbor (he's up there in years, and his recollection of what has been done so far was not helpful), the alternator had been working for years, then he had it rebuilt (at a reputable shop). I would hope they would return it setup the same as they received it. After he installed it, it worked for a while.

I've never messed with positive ground. Based on the replies above, if he is correct that it charged the battery for a while, it must be a positive ground alternator? I'm guessing the only way to be sure would be to take it to the shop and ask?

My neighbor suggested we convert it to negative ground,I was concerned about what direction the starter would turn if we did that.

One other quick check to rule out would be a battery that is charged up backwards. generally this happens when battery is low or dead and a charger is hooked up backwards. Easy to check with a multi meter, is battery 12 volts or -12 volts. Doesn't happen often but will mess with your head. Steve.

 

[rasento]

Here's the resolution to our story:

When they converted from 6v generator system to 12v alternator years ago, they left it positive ground. When my neighbor took the alternator to be rebuilt late last year, he didn't appreciate that the alternator was positive ground, and didn't tell the shop it was positive ground. I guess it was rebuilt without paying attention to how it was set up, and rebuilt as negative ground. When it was installed and first run, the smoke came out of the diodes.

Last week, The shop rebuilt it again as negative ground, we swapped the battery ground, replaced the ammeter with a volt meter, and life is good.

Thanks for your help.

 

[wore out]

Here's the resolution to our story:

When they converted from 6v generator system to 12v alternator years ago, they left it positive ground. When my neighbor took the alternator to be rebuilt late last year, he didn't appreciate that the alternator was positive ground, and didn't tell the shop it was positive ground. I guess it was rebuilt without paying attention to how it was set up, and rebuilt as negative ground. When it was installed and first run, the smoke came out of the diodes.

Last week, The shop rebuilt it again as negative ground, we swapped the battery ground, replaced the ammeter with a volt meter, and life is good.

Thanks for your help.

Thanks for posting back with the solution!

It confirms what I wrote previously "(+) ground alternators are readily available to those who want them and despite what some of you think are NOT as rare as 3-legged unicorns!".

 

[Duner Wi]

Thanks for the end of the story. Ammeter and coil wires probably could be reversed around now too. Last time I checked you could get 10si alternator in
6,8,12 or 24 volt ,either negative or positive ground.

 

[olddavid]

Yes I understand that’s probably true but my point is what’s he have? And if he does have this it’s relatively uncommon at least special order from somewhere probably not walking into the parts store in town to get one? he also talks about rebuilding it something much more commonly done on a generator although if your positive ground alternator is a level up more expensive wise that might make sense the whole idea of alternator is a little more on the throw away plan 100 dollars or less if you really want to gets you a new one. Few can justify tinkering on it. Generally bearings kept inside the shed and vr actually had about the same lifespan anyway.
My point is let’s see that alternator and the unhooked wire...if it’s a single wire is it one leftover from a vr or is it supposed to go where wore out drew it as part of the conversion harness that got left off?

Yes, confirm generator or positive ground alternator or whatever. An external voltage regulator could be anywhere and out of sight. Did the owner have the battery out and assuming positive ground hooked it up backwards?

 

[Janicholson]

Here's the resolution to our story:

When they converted from 6v generator system to 12v alternator years ago, they left it positive ground. When my neighbor took the alternator to be rebuilt late last year, he didn't appreciate that the alternator was positive ground, and didn't tell the shop it was positive ground. I guess it was rebuilt without paying attention to how it was set up, and rebuilt as negative ground. When it was installed and first run, the smoke came out of the diodes.

Last week, The shop rebuilt it again as negative ground, we swapped the battery ground, replaced the ammeter with a volt meter, and life is good.

Thanks for your help.

Again thanks. Woof what a trial. Jim

 

[Fixingfarmer]

Thanks for posting back with the solution!

It confirms what I wrote previously "(+) ground alternators are readily available to those who want them and despite what some of you think are NOT as rare as 3-legged unicorns!".

Hmm seems to me the shop that rebuilt it twice as a negative ground might have paused to check especially the second time if said unicorn population had been taken off the endangered species list.

 

[used red MN]

Hmm seems to me the shop that rebuilt it twice as a negative ground might have paused to check especially the second time if said unicorn population had been taken off the endangered species list.

Yes, thanks for coming back and giving us a closeout on this!
Seeing what Fixing farmer wrote and not being sure I am decoding it right I will add this. I am trying to figure out why woreout is such a proponent here of positive ground alternators. I think his main deal is he wants to be “right”! It swells up everybody when they confirm they have “out guessed the guessers” Okay, yes they are available but I personally wouldn’t pay a dollar more for one when the machine can easily be swapped to a negative ground. And then when it comes time for a jump start there is no confusion. The only time I would see an advantage may would be if your machine had electrical fuel gauge or temp gauge that were polarity sensitive. The poster said they changed it to negative ground and added a voltmeter, so we won’t know which way it was actually set up per how the ammeter registers. Although the coil connections might tell us if the original “conversion guy” was a detail man and did things right. I hate to say the gentleman that the OP is helping is wrong but I am going to say the original alternator conversion was negative ground. And the gentleman just thought all along it was positive and swapped the cables when he put the alternator on that was rebuilt negative ground. Whatever, water under the bridge the guy’s tractor is fixed. It will be interesting to see if the OP hangs around here and comes back to view this. I do agree with Duner, a final check of ignition coil polarity is in order. If it is found to be correct, then hummmm?

 

[wore out]

Yes, thanks for coming back and giving us a closeout on this!
Seeing what Fixing farmer wrote and not being sure I am decoding it right I will add this. I am trying to figure out why woreout is such a proponent here of positive ground alternators. I think his main deal is he wants to be “right”! It swells up everybody when they confirm they have “out guessed the guessers” Okay, yes they are available but I personally wouldn’t pay a dollar more for one when the machine can easily be swapped to a negative ground. And then when it comes time for a jump start there is no confusion. The only time I would see an advantage may would be if your machine had electrical fuel gauge or temp gauge that were polarity sensitive. The poster said they changed it to negative ground and added a voltmeter, so we won’t know which way it was actually set up per how the ammeter registers. Although the coil connections might tell us if the original “conversion guy” was a detail man and did things right. I hate to say the gentleman that the OP is helping is wrong but I am going to say the original alternator conversion was negative ground. And the gentleman just thought all along it was positive and swapped the cables when he put the alternator on that was rebuilt negative ground. Whatever, water under the bridge the guy’s tractor is fixed. It will be interesting to see if the OP hangs around here and comes back to view this. I do agree with Duner, a final check of ignition coil polarity is in order. If it is found to be correct, then hummmm?

''I am trying to figure out why woreout is such a proponent here of positive ground alternators. I think his main deal is he wants to be “right”! It swells up everybody when they confirm they have “out guessed the guessers”''

That's a REALLY nasty comment, used red, and UNCALLED FOR.

I have NEVER said I am "a proponent" of (+) ground alternators, I have simply stated that they are readily available to those who choose to use them, and NOT to rule out the possibility that someone has installed one, when things don't check out as expected.

Personally, I have never used a (+) ground alternator, but certainly wouldn't be opposed to doing that if that's what a customer wanted.

 

[used red MN]

''I am trying to figure out why woreout is such a proponent here of positive ground alternators. I think his main deal is he wants to be “right”! It swells up everybody when they confirm they have “out guessed the guessers”''

That's a REALLY nasty comment, used red, and UNCALLED FOR.

I have NEVER said I am "a proponent" of (+) ground alternators, I have simply stated that they are readily available to those who choose to use them, and NOT to rule out the possibility that someone has installed one, when things don't check out as expected.

Personally, I have never used a (+) ground alternator, but certainly wouldn't be opposed to doing that if that's what a customer wanted.

Okay, maybe I went over the top just to say “everyone likes to be right” I apologize that I directed it at you. To spring board off what Fixing Farmer has said here’s this. I have probably had 100 Delcc10si alternators apart to repair. Testing the rectifier with an ohm meter maybe you could do it and not necessarily pay attention to your meter leads. You could just make sure the polarity of the 3 on one side matches and the 3 on the opposite side match in opposite polarity. Maybe they looked at it and some were visibly blown out so they chucked it and grabbed one of their regular negative ground units and stuck it in there. I would think there would be some marking on it that identifies it as a “positive ground” unit. I also believe the diode trio would be different in a positive ground. If that tested good and they put it back in I don’t think the alternator would charge on the test stand. Same with the voltage regulator, maybe they just practice replacing it and trash the old one they are fairly cheap if bought in “rebuilder” quantities. Again I would have to believe there would be some marking on it identifying it as a “positive ground” unit. As pointed out above “it could be missed that by the shop that it came in as a “positive ground” alternator and sent it back out as a negative ground. If they did notice it at some point I would think they should call the customer and say.. hey, this was a positive ground alternator what is it off of, do you want us to repair it that way? If this was missed the shop was pretty poor.
My scenario is it came into the shop as a common negative ground alternator and repaired as one, no different than the 10 others the shop did that week. The only problem was when the owner connected the battery recalling the “glory days” when it was new and the fact that it was a “positive ground” tractor.