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Battery Positive or Negative Ground

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  • Battery Positive or Negative Ground

    I have this 1950 Automobiles book by Floyd Clymer. It's a good book with loaded with pictures and specs for all the American cars made in 1950. I was checking the battery ground specs, and of the 34 car makes, 22 had positive ground. So, with almost twice as many using positive ground in 1950, I'm surprised they settled on negative ground when they changed to 12 volts just 5 and 6 years later.

    Clymer 1950.jpg

  • #2
    Yes Tom, it is interesting, and knowing electricity as intimately as I do, I see no reason why positive was chosen over negative by some and negative chosen over positive by others. We all know that people are fickle, and the industry was populated with people.
    You wana look waaay far up da road and plan yer route because the brakes are far more of a suggestion than a command!


    • #3
      Originally, the voltages on the wires were positive with respect to earth. This is called negative ground, since the negative side of the battery is grounded to earth. Then engineers discovered that with positive voltage on the copper wires, copper wires age quickly, due to electrolysis. With negative voltage on the wires, in respect to earth, (called positive ground) the copper is protected from corrosion. This is referred to as cathodic protection.

      It is partly a matter of convention and standards, and partly because positive earth encourages galvanic corrosion* of the surrounding bodywork - whereas with negative earth is is the much-easier-to-replace electrical contacts that corrode.

      3~ Tudor's & 1~ Coupe
      Henry Ford said,
      "It's all nuts and bolts"
      "Start by doing what's necessary; then do what's possible; and suddenly you are doing the impossible."

      Mitch's Auto Service ctr


      • Mitch
        Mitch commented
        Editing a comment
        You guys learned something today.. lol

      • pAAt
        pAAt commented
        Editing a comment
        Everyday Mitch !! Brain hurts, time to drive tractor

        BILL WILLIAMSON commented
        Editing a comment
        WHY do they call it "EARTH"? D.C. never goes to the DIRT, like that A.C, that'll KILL YOU!--Here, a Guy was drilling, in a wet Hot Water Closet, with an Old Alujimum, 2 wire drill & ELECTROCUTED himself!!!
        Dad Puzzled?

    • #4
      Working on pipelines I have used cathodic protection. Not to mention what different types of crude will do to lines.


      • #5
        Here's another one for sale cheap on ebay right now. It's really amazing the amount of research Floyd did to be able to publish this book with so many specs on everything from wheel alignment to engine bearing sizes and materials. I was really surprised when I wrote a letter to Floyd Clymer in 1970 and was still able to buy the book for the cover price of only $2. In 1976 I was still able to buy my 1949 and 1952 books for $2 each. Every time I need a spec for my 1950 Studebaker, this is the book I look at first, because it has everything from fan belt size to battery cable size and length. There's even a spark plug chart comparing heat ranges of several brands of plugs.

        These books are also available in other years, and I will buy the 1953, if one comes up cheap.
        Just do an ebay search for "Catalog of 1950 Automobiles" and 5 of them are on ebay right now.


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