Wiring diagram for OC4 12v Alternator Conversion

[mmoscari]

My 1956 OC4 came with an alternator.  It doesn't charge the battery.  My Battery is wired with a Positive Ground.  I want to be sure that the conversion was wired correctly before I look for a new alternator.  I know how to wire a Negative ground alternator, but I'm not sure about positive ground systems. I dont want to fry anything.  Can anyone help with a scematic?

[Jim N]

I converted my OC4 from a 6 volt, positive ground, generator  to a 12 volt, negative ground, alternator system a couple of years ago.  The alternator came out of a Toyota truck. I used this small one since I did not wish to cut any sheet  metal.
I suspect your charging system should be negative ground also, since it has an alternator.  It all depends on what the alternator is set up for.

[mmoscari]

Thanks for the reply, Jim.  My battery is connected with the POSITIVE connected to Ground.  The alternator is very small, I have no Idea what it came off of.  I havent started to investigate yet, but I dont think the alternator can be wired with a negative ground.  For me to switch to a Negative Ground I think I would need a new starter? It would turn in reverse.

[hotratz]

If the starter is a permanent magnet type it will turn in reverse. If it is a wound stator field type it won't care what polarity you apply. See if a screw driver blade sticks to the side of it. If it does it's a permanent magnet type. If it doesn't you should be good to go.

[mmoscari]

A Negative ground system would be a plus, but what about the Magneto?  Would I have to re-wire it?  I definitly dont want to fry that.

[John Schwiebert]

There is no current from the charging system that goes to the magneto. Me I do not care for single wire alternators. Since your tractor has a mag you may need a shut off switch controlled by oil pressure so the alternator does not run the battery down, but that may depend on what alternator you buy.

[Jim N]

I had to add a contact to my kill switch, to open up the field circuit for the alternator.  My starter was not permanent magnet and works fine. ....actually a little better since it spins the engine faster to start.