UTS 12 volt conversion

Mark Poss

Well-known Member
I just got an 1948 UTS and would like to convert it to 12 volt. I was planning on taking the generator to my local starter and generator shop to have it converted to 12 volt and pick up a 12 volt coil. What type of coil should I get? One with internal resistor? Im not very good with electrical. I know I need to replace the light bulbs with 12 volt ones. Will the 12 volt battery be positive ground still or negative ground? Can someone post a wiring diagram for the 12 volt conversion for me to follow? Thanks for any help, Mark
If the coil you currently have is good, all you need is a resistor for it. If you need or want a new coil, I would get one that does not require an external resistor.

To answer your original question--if you keep the generator, it would most likely remain positive ground. An alternator conversion would be negative ground.
I had my generator rebuilt into a 12v on my ZAS/LP, it is very expensive. I also installed a new voltage regulator which is for negative ground, you can get that voltage regulator in either + or- ground. I can send you both the generator and alternator diagrams if you'll send me an email.
I don't know how to put pictures on here
1. Converting to alternator with built in regulator would be much cheaper and more dependable. Your problem will not be with generator but in finding a dependable regulator. But if you want to stay original that is your call.

2. You do not need a diagram to change to 12 volt generator unless you also change to negative ground. 6 and 12 volt generators wire the same except for added resistor with 6 volt coil. A generator will work equally well either polarity. Just make sure you have a regulator that matches your ground polarity and polarize the generator before you start the engine the first time.

3. An IC14SB NAPA coil or equivalent would eliminate the need for a resistor

4. To change to negative ground, reverse connections on coil and ammeter and connect battery negative ground. Starter, lights, and ignition work either polarity.

Here are a couple of old diagrams that may help


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