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positive ground electric system

Discussion in 'The Hokey Ass Message Board' started by novarat71, Dec 13, 2012.

  1. novarat71
    Joined: May 20, 2010
    Posts: 9


    Can someone explain how a 6 volt positive ground system works?
    How is wired differently than a negative ground system?
  2. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    The positive battery post is grounded to chassis, the negative feeds everything electrical, generator is magnetise/polarized to put out juice in the correct direction.
    For basic parts of the car like starter and lights, direction of ground is immaterial.
    Fancier doo-dads like radios may care which way their electricity goes, but don't worry, the smoke will clear quickly.
  3. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,608

    Rusty O'Toole

    When 6 volt systems were popular most cars were + ground. All Ford, Chrysler, most independents, and some GM makes. A few cars were - ground.

    Then when 12 volt came in everyone went - ground for some reason.

    Either one works the same but once you have one system you have to stick to it.
  4. Mr48chev
    Joined: Dec 28, 2007
    Posts: 30,191


    Actually there are some 12V cars that are + ground. Nash Metropolitans for one as I had one. When the Lucas generator died and I couldn't afford a replacement one of my buddies suggested I put a Chevy Generator and regulator on it and a couple of hours later I was going again after reversing the wires on the ammeter and reversing the cables on the battery. The guy I traded the car to after I blew the motor up threw the generator away as he hooked the battery back up + ground and the ammeter read a discharge all the time.

    Novarat71 the + ground - ground thing is all based on electrical theory and Bruce is correct in that if you study dc electrical theory the electron flow makes more sense with a + ground. Somewhere along the way it was decided that The + for the "hot" side and the - for the neg or ground side was easier to deal with and it stuck.

  5. British cars were 12v + ground up until 67-71 depending on the brand
    Early Datsun's were + ground until '65
  6. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856


    Don't think about it. If you try thinking about it, smoke will come out of your ears. Just put the battery in "backwards" and move on with life.
  7. Cantstop
    Joined: Jul 11, 2005
    Posts: 239


    I believe that I read somewhere ( so I could be full of it but I don't believe so) that it had to do with RF interference and the AM radios reception abilities.
  8. ehdave
    Joined: Feb 28, 2009
    Posts: 119


    My 56 aussie built desoto diplomat (basically a 53-4 plymouth with desoto trim and grille) is 12 volt +ground, although i'm totally rewiring the car with a 12 volt - earth when i get to that stage. Any one got an idea how to rewire the dash?
  9. plym_46
    Joined: Sep 8, 2005
    Posts: 4,018

    from central NY

    Swapthe terminals on the ammeter, and reverse the wires on the coil. Done
    Last edited: Dec 14, 2012
  10. 50 Ragtop
    Joined: Aug 12, 2009
    Posts: 52

    50 Ragtop

    What about when hooking up a battery charger? Do you still hook it up say red to pos and black to neg. or does it matter?

  11. Bryan G
    Joined: Mar 15, 2011
    Posts: 188

    Bryan G
    from Delmarva

    Yes, positive to positive, negative to negative. The battery charger doesn't know any different nor does it care.
  12. hoggyrubber
    Joined: Aug 30, 2008
    Posts: 572


    it does care if you hook it up with the pos to the neg post, even if it is the "hot" post. :D don't ask me how i know. i got stuck in a pos ground way of thinking and need to give the bat a quick charge.
  13. ehdave
    Joined: Feb 28, 2009
    Posts: 119


    Cheers for that, sound pretty simple. I thought it would be a lot more work than that.
  14. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856


    Don't forget to polarize the generator.
  15. That's because the Negative post is NEVER the HOT post. It is still negative and the Positive is still positive ~ they are just flowing the opposite way through the car.
  16. ehdave
    Joined: Feb 28, 2009
    Posts: 119


    Thanks for that, looks like this build will only need the ammeter done seeing as the only origional electricals will be the dash but its good to know for future projects.

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