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POS or NEG Battery Disconnect switch

Discussion in 'The Hokey Ass Message Board' started by The37Kid, Mar 28, 2013.

  1. Positive Side

    131 vote(s)
  2. Negative Side

    118 vote(s)
  1. The37Kid
    Joined: Apr 30, 2004
    Posts: 27,953


  2. Don's Hot Rods
    Joined: Oct 7, 2005
    Posts: 8,319

    Don's Hot Rods
    from florida

    Yep, it depends on your philosophy of what the switch should do. If you just want it to shut off the current flow, then either way works. I like to put it on the positive cable, very close to the battery, because it kills any current flow right there and doesn't let it go any further. But that is just my way of thinking.

  3. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,792


    I always thought they were supposed to go on the POS. That would kill power to everything.
  4. richie rebel
    Joined: Oct 8, 2007
    Posts: 1,184

    richie rebel

  5. Bad Eye Bill
    Joined: Sep 1, 2010
    Posts: 841

    Bad Eye Bill
    from NB Canada

    Negative side at the battery does exactly the same thing.

    You have two posts on the battery, a cable goes to each one, break either cable, you have no current flow, it makes no difference.
  6. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,451


    Yep, no difference at all.

    Posted from the TJJ App for iPhone & iPad
  7. fastcar1953
    Joined: Oct 23, 2009
    Posts: 2,474


  8. mrspeedyt
    Joined: Sep 26, 2009
    Posts: 609


    ground side...but the other post is better than none.
  9. Oppy
    Joined: Feb 10, 2006
    Posts: 72


    So I did negative, not sure why. Had it like that for years, no problems. I did hide the switch, kinda use it for a security switch.
  10. junk yard kid
    Joined: Nov 11, 2007
    Posts: 2,719

    junk yard kid

    i say negative and heres why. The switch is rated at a steady amp and a momentary amp. Well if the electrons are flowing from the positive to the negative and some are getting used up by the starter and/or the system so there should be less going back into the battery. Thus less amps on the switch.
  11. simplyconnected
    Joined: Jun 5, 2009
    Posts: 64


    It depends on whether the electrons are painted Ford Blue, Chevy Orange, or Plymouth Sub-Lime. Yes, I know there are three choices. Mom & Dad had three kids; one of each.
  12. 48FordFanatic
    Joined: Feb 26, 2011
    Posts: 1,335

    from Maine

    You should always "switch " the hot side of any circuit.
  13. I used the Neg. side. that is what Caterpillar does.

  14. no, the current flow before and after is the same.
    Bob, it will actually work fine on either but i always put it on the positive side. rule of thumb is to always switch the positive most switches/fuses are on the positive side. horns, and early ford starter buttons are a couple exceptions to the rule that prove it will work fine either way.
  15. hemi rodder
    Joined: Oct 10, 2011
    Posts: 510

    hemi rodder
    from NB Canada

    actualy the electrons are leaving the negative side of the battery and are being attracted by the protons on the positive side battery terminals:D this is the scientific explanation but then there is the theory explanation + to - flow that we see in diagrams and books:rolleyes:
  16. keyster
    Joined: Dec 27, 2011
    Posts: 26


    I like to switch the negative side.
    I feel there are less positive terminals that way.
    If something should short the negative terminals to ground, no problem. The shut off may not work, but no fireworks.
    If the positive terminals gets shorted to ground, bad news.
    There is usually no fuse on the battery cable.
    If it shorts it will get ugly.

    I can't see that it makes any difference electrically.
    Last edited: Mar 29, 2013
  17. JeffreyJames
    Joined: Jun 13, 2007
    Posts: 16,612

    from SUGAR CITY

  18. John T.
    Joined: Nov 6, 2008
    Posts: 233

    John T.

    NHRA rule book says Positive I say negative. I have relays that are wired straight to the battery. In an event I need all power cut off I want to know everything is shut off.

    I guess that's why I don't run NHRA
  19. 59 brook
    Joined: Jun 12, 2005
    Posts: 1,017

    59 brook

    pos and i'll give you a perfect example why. last weekend i went to change the motor mounts on my wagon. i had to drop the starter to get to the pass side. when i reinstalled the stater i somehow caught the starter tobattery cable between the starter and the block. as soon as i began to screw the little green knob on my disconnect it made a spark at the pos batterm and the starter. now if it was on the neg post my guess is that due to the fact that the engine was grounded to the frame and body i believe istill would have had a path for electricityto flow and to stop it i think i would havehad to physically remove the pos cable probably severly burningeither my hand or watching the electric system burn up. just my 2 cents. ifit's better to break the ground why do we put a fuse close to the battery when we run power to the trunk for something like a fuel pump or stereo. can't ever remember seeing a fuse on a ground wire
  20. bangngears
    Joined: Aug 30, 2007
    Posts: 946

    from ofallon mo

    Negative side,that way your battery doesnt charge thru the switch.
  21. Neg. That way there is absolutly nothing the pos side can short to.
  22. bobscogin
    Joined: Feb 8, 2007
    Posts: 1,761


    It's like arguing which terminals the wires should go on when wiring a single pole, single throw toggle switch.

  23. Dreddybear
    Joined: Mar 31, 2007
    Posts: 5,996


    Every Race organization I've belonged to makes you wire it to the positive side.
  24. 5window
    Joined: Jan 29, 2005
    Posts: 8,052


    Oh,Lord. Look-if it's on the positive side, the only thing powered, that could short or shock you, is the short stretch of cable from the battery to the switch.

    If it's on the negative side, EVERYTHING has power to it and is only waiting for a stray opportunity to be grounded and powered up. So your choices are 6" of wire vs your entire car!

    Why is this so complicated-please don't work on any rockets. :)
  25. The37Kid
    Joined: Apr 30, 2004
    Posts: 27,953


    5window, are there heavy duty or race car rated terminal covers that would protect that six inch danger zone? Bob
  26. old jetstar
    Joined: Dec 29, 2011
    Posts: 43

    old jetstar
    from oswego,KS

    With the shutoff on the negative post If something metal falls against the negative post or the battery falls over and the neg. grounds out,this will power everything up even with the switch shutoff....I suppose racing rules use it on the positive side so when there's an emergency such as a wreck when they shut off the disconnect,they're sure it's really off...
  27. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856


    OK, in order to illustrate the futility of these arguments, what if the car has positive ground?

    It doesn't matter which terminal the switch is on. If one side of a battery is disconnected, the entire battery is disconnected from a circuit.

    Oh, and in DC circuits the electrons flow from negative to positive.
  28. Bad Eye Bill
    Joined: Sep 1, 2010
    Posts: 841

    Bad Eye Bill
    from NB Canada

    If it's on the negative side, NOTHING has ground to it but the short stretch of cable from the battery to the switch. It's not complicated, break either side = no current flow.

    Anyway, no sense arguing about it I guess, everyone is free to do as they choose.
  29. It is somewhat embarrassing to read what people think electricity does or does not do!

    If you break the circuit on a DC system at any point it accomplishes the same thing. Whether positive or negative you'll still have a "danger zone" where a circuit can be completed. The closer the switch to the battery the smaller the "danger zone".


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