Battery Question from todays CarTalk..

Discussion in 'The Garage' started by ThorRex, Feb 8, 2014.

  1. markgsnw

    markgsnw WTF?

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    So did the Yanks. My dad's Pontiac was 6 volt positive ground. Sometime in the late 50's it was discovered that negative ground was a better set up.
    #21
  2. Motomantra

    Motomantra Registered Lurker

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    Thanks for the correction. Foggy times, back then.
    #22
  3. def

    def Ginger th wonder dog

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    Many UK automotive applications were pos.(+) ground. My brother's Triumph motorcycle is + ground....Joe Lucas!!!??!!
    #23
  4. ttpete

    ttpete Rectum Non Bustibus

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    Original VW was link and pin front end with 2 torsion bars. At some point they switched to link and 2 ball joints, still torsion bars. The Super Beetle had McPherson struts and coil springs.

    6 volt Fords were positive ground, as were 12 volt Lucas equipped Brit cars and bikes.
    #24
  5. P B G

    P B G Long timer

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    Never seen that happen.

    Jumped 6V porsches, tractors, trucks etc.

    I have an 8V battery around specifically these days for when such vehicles act up.
    #25
  6. Jayrod1318

    Jayrod1318 Poster

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    Assuming things are as they should be are often the culprit...

    My BIL had a little honda car, local shop made an engine swap with a complete motor including accessories.

    Tech could not get car to run correctly, different codes getting thrown out, sensors, wire harness, and ultimately the CPU was replaced over the course of a couple weeks. No go.... same issues. Bad CPU? tried 2 different ones... same result...

    Tech ended up referring car to local dealer out of frustration, same thing, harness, cpu, same result...

    At this point the car had been mulled over by a dozen people, ultimately it was the suggestion of a onlooker at the dealer that someone ought to replace the alternator.

    Problem solved, alternator was supplying dirty current to system and ultimately causing the erratic behavior and apparent wire harness and cpu issues..

    80$ part literally caused thousands of dollars of labor and parts swapping and stumped more than a dozen people.
    #26
  7. riverflow

    riverflow Adventurous Commuter

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    My neighbor has a BSA Royal Star and it's a positive ground. It also has specially sized nuts & bolts so you had to buy their tool to open just about anything. Brits.
    #27
  8. GSWayne

    GSWayne Old Guy nOOb

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    Anybody know why they switched to negative ground? A positive ground system will reduce the corrosion if the wiring gets wet.
    #28
  9. ttpete

    ttpete Rectum Non Bustibus

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    They didn't do that on purpose. Whitworth was British standard at the time they were built. You should have been around 60 years ago when it wasn't possible to buy metric tools at the local store, either.
    #29
  10. eric1514

    eric1514 (R)

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    Mostly for standardization.
    #30
  11. SPEIRMOOR

    SPEIRMOOR Been here awhile

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    My Norton Commando is Positive ground. If you have a battery tender pigtail with this setup ensure you have the plug cap on when not in use. Otherwise it may short out if it touches the engine, Bare part of frame etc.
    #31
  12. victor441

    victor441 Long timer

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    That is only the case when conductors literally contact the earth/ground...i.e. the telephone system runs on 48V positive ground, the polarity makes no difference corrosion wise on a vehicle. Vehicles were probably positive ground in the early days as a carryover from the standard in telegraph and telephone systems.

    http://lyle.smu.edu/~levine/ee8320/positiveground.pdf
    #32
  13. DC2wheels

    DC2wheels Castle Anthrax troll

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    Lucas didn't quit producing crap when they went to 12V.

    I had a '73 Land Rover Series IIa. Nice truck. Absolute primitive electrics. Ended up replacing many of the connections and most of the components.

    Prince of Darkness indeed. :huh
    #33
  14. HD Steve

    HD Steve Nonposer in Training

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    60 Jag Mark II Sedan. Bought it in college. What was I thinking??

    Positive Earth and Lucas electronics....Lucas, the prince of darkness.

    Wired and isolated a tape deck...had to have tunes. Hit a bump and replace the fuse. Bought em by the case.
    #34
  15. Beezer

    Beezer Long timer

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    the ground was made negative because the other way makes the frame an anode.... as in sacrificial anode. good for the wires.... ya, probably. bad for the frame though. many (if not most) positive ground Brit machines had separate wires to carry the ground side of the circuit because using the structure to carry the current caused corrosion
    #35
  16. ttpete

    ttpete Rectum Non Bustibus

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    The Brits went to positive ground in the mid-1930s for a couple of reasons. One was that if the body of the spark plug was positive, it required less voltage to fire it. The other was to reduce corrosion at the positive battery terminal. This is from several British auto engineering texts that I have in my library.

    Ford used positive ground until they went to 12 volt systems in the mid-1950s.

    I worked in import car shops for a number of years, and can't recall anything but ground return systems that used the chassis. Some things needed to be bonded together for various reasons like rubber motor mounts, and generator-to-regulator wiring, but that was the extent of it. Headlights were just grounded to the sheet metal nearby, as were tail lights.
    #36
  17. Beezer

    Beezer Long timer

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    after looking at posts here and in other places I see there is a lot of difference of opinion. maybe I'm wrong. my beliefs are based on my experience. when I was old enough to mess around with fixing cars, etc, in the 60's my neighbor across the ally was running a small garage. he was a pro mechanic, retired from working on school buses. he's the guy that told me about positive ground problems they had had with older rigs that were pos ground. I confirmed that in my own mind with a 48 GMC pickup I owned for a while. Between me and my brothers, we had half a dozen throughout the late 60's and 70's. mostly they were converted straight off. maybe not required? anyway, maybe in a perfect world where there is zero resistance connections there is no difference.... and there seems to be a lot of posting to that effect, but I have also done more than a bit of plating, etching, and electrochemical cleaning. in every case, whatever is on the plus side of the power source gives up material. no question on that one. I also owned at least a dozen Brit bikes over the years from '68 to 2006.... all of them had a ground wire system in parallel to the frame (none were newer than '73)
    #37
  18. ttpete

    ttpete Rectum Non Bustibus

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    There's a reason to run a ground wire to the headlight on those bikes. It's because it's not a good idea to run current through the ball bearings of the steering head. Some had the zener diode for the charging circuit on the lower triple clamp as well, which meant that there could be 10 amps load on that wire. The tail and stoplight, however, didn't have a separate ground wire.
    #38
  19. Beezer

    Beezer Long timer

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    always nice to post stuff like that for those that don't know. bikes may be a hobby for me, but I also have 40 years as an aircraft mechanic, so pretty much aware of things like that. whatever.... point is, you can't deny the physics of what happens when everything is cathodic to a structure that is a large anode. it's just plain harder to control corrosion
    #39