Positive Ground Alternators
 

I have a 31 A that was successfully converted to a 12 V Positive Ground. I was having problems with the alternator and changed it out for a new 10SI, 60 amp unit. Easy one wire install, but had bad results when going to jump the car. I think I need a positive ground alternator. I know there has been some debate on the reality of a positive ground alternator on this blog so I am asking again. Is there a need to run a positive ground 10SI alternator in a positive ground installation?

Re: Positive Ground Alternators
 

If you car is wired positive ground you need a positive ground voltage source, Negative ground a negative ground voltage source.

Re: Positive Ground Alternators
 

Hey Chris, welcome to Fordbarn.

Personally, if you have had issues jumping a positive ground system, the cause is 'operator error' and really not the fault of the system, but that's ok but just know a positive ground system CAN be successfully boosted off of a negative ground system.

If you do decide to reverse the polarity to a negative ground, the only two things that really needs to happen is reverse the polarity on the coil by exchanging the two wires and place them on the opposite respective terminals, and to reverse the wires on the backside of the ammeter. Hopefully your battery cables are long enough to be reversed too, but that should get you to a negative ground.

Since the 'one-wire' alternator has an internal self-exciting regulator that always has a current draw on the system, you might consider installing a disconnect switch to interrupt the current when the vehicle is not in use. Another alternative is to install a Model-A generator back on there with a diode equipped cut out and an EVR installed internally where you can eliminate the about half of your headaches and allow the engine compartment to look more aesthetically correct.

Again, welcome to the Forum here!!

Re: Positive Ground Alternators
 

I would consider changing the ground over to negative if you have to replace the alternator. Some of the advantages of the 12 volt alternator are lost when you go positive ground such as many of the negative ground alternators are for modern cars and are over the counter at a parts store if you need one on the road and some modern electronics are polarity sensitive which means you should have a negative ground system.

Charlie Stephens