Changing Dynamo Polarity

JohnnyBoy · Post by **JohnnyBoy** » Fri Oct 08, 2010 12:19 am

I'm considering changing the polarity of my Fordson from (+) Positive earth (ground) to (-) Negitive earth (ground). It's a long time since I did this but somebody correct me if I've got this wrong, and before I set fire to something.

If I fit the battery as Negitive earth first then I take a wire from the positive battery post and hold it on this dynamo terminal for a few seconds,

Then the Dynamo should be re-polalrised to charge as a negitive earth system?

JC · Post by JC » Sat Oct 09, 2010 8:06 am

You're right, JB, but disconnect the wires from the dynamo before you do it.

icom102 · Post by **icom102** » Sat Oct 09, 2010 8:49 pm

What is the advantage of doing this ?

JohnnyBoy · Post by **JohnnyBoy** » Sun Oct 10, 2010 11:26 pm

Thank JC, I’ve only done it a couple of times and that was back in the early 70’s when we were fitting negative earth radios into positive earth cars.

JohnnyBoy · Post by **JohnnyBoy** » Sun Oct 10, 2010 11:59 pm

icom102 wrote:What is the advantage of doing this ?

It’s a personal preference, I plan to have a small workshop in a trailer which will have a power supply via a heavy duty cable and Anderson connection to the tractor which will give me a 12v power supply for accessories such a hand lamp. I want to install a radio in the trailer which means the trailer chassis would need to be negative earth so whilst I’d have no problem towing the trailer from A to B, when I wanted to couple the electricals up, then I’d need to uncouple the trailer first…

…does that make sense?