Charging Question

D

Dennis D 1929

Member
My barn find 1929 Coupe has a strange issue. The amp meter seems to run "backward". With engine off, and key off, if you pull the lights on, it reads +10 amps. Engine running reads -5 to -10 amps. The gauge looks like a new replacement, so my guess is someone put it in backwards or set it up that way to accommodate a neg. grounded battery. Could I just fix the issue by taking the gauge out and switching the wires or just switch the battery back to neg. ground ? Are there any known issues to running the car with a neg. grounded battery ? My guess is they built the car as positive ground (from what I've been told) for a reason. Thanks for any comments.
 
A lot of the ammeters that have been offered are actually 26-27 model T . The 26-27 model T was negative ground .These ammeters look and fit pretty much the same as the model A ammeter . If this is the case , I would do what midget racer says above .
 
Where is the positive terminal of the battery connected? It was connected to the frame originally. This could explain the ammeter if the neg is now attached to the frame.
 
Chief hooked his Ammeter BACKWARDS for LAFFS & an excuse for NOT takin' "someone" to TOWN!!!---He taught me to be KRAZY, also!
Bill Fun
 
Also it should go to zero when the key is off. This is important, because if it still reads plus or minus you have a stuck cut-out relay.
 
Had the same problem last year. Put in a new amp meter, had to reverse wires for it to read correctly. Enjoy.
 
I think that most if not all of the model A parts vendors have been offering the 26-27 model T ammeters as replacements for the model A ammeter for 20 years or more .
 
Dennis D 1929 said:
My barn find 1929 Coupe has a strange issue. The amp meter seems to run "backward". With engine off, and key off, if you pull the lights on, it reads +10 amps. Engine running reads -5 to -10 amps. The gauge looks like a new replacement, so my guess is someone put it in backwards or set it up that way to accommodate a neg. grounded battery. Could I just fix the issue by taking the gauge out and switching the wires or just switch the battery back to neg. ground ? Are there any known issues to running the car with a neg. grounded battery ? My guess is they built the car as positive ground (from what I've been told) for a reason. Thanks for any comments.
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Had the same situation on my 1930 Model A! Same thing, ammeter reading opposite, the difference for me is my battery went dead! Tried hooking up a 6 volt battery charger and bingo, lots of sparks, someone, had not understood the battery being positive ground. Got that fixed the battery charged and off the old girl went with ammeter reading right.

The original model A Ford generator did not care how the battery was installed, as it is self polarizing, which means no matter how the battery is installed the generator will polarize and work to charge the battery.
 
The thing is , the generator will need to be repolarized . To repolarize the generator is to touch a wire from one terminal to the other terminal of the cut out for a second or two . Never try to repolarize the generator if a can style voltage regulator is in use . Repolarization should only be performed with a cut out in place .
 
Purdy Swoft said:
The model A generator can't repolarize itself .
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Trust me, I thought it strange also! But, for my old car, reversing the bat leads, did the trick and the gen hesitated a bit on charging but did pick up and start charging positive ground.

I too, do not understand, probably should not have posted that I did it!
 
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