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Quick question on dual batteries.

Discussion in 'Truck & Equipment Repair' started by danno, Feb 24, 2006.

  1. danno

    danno Senior Member
    Messages: 401

    I`m hooking up 2 batteries. I know its been brought up, and I checked the "search". But as far as the "Negative" cable. Should I ground it right to the frame, coming off the 2 battery ? Or run it over directly, to the negative post on the primary battery ?

    NEUSWEDE Senior Member
    Messages: 949

    The the negative from the first battery to the second battery, don't ground it to the frame.
  3. danno

    danno Senior Member
    Messages: 401

    Got it. Someone also said to hook up a "small" wire going from the 2nd battery ground, to the frame besides the regular cable ?
  4. justme-

    justme- 2000 Club Member
    Messages: 2,138

    Truithfully, I don't think it matters as long as the truck has good grounds anyway.

    Factory installations always run both negs to ground- never to each other.
  5. danno

    danno Senior Member
    Messages: 401

    So you`re saying it doesn`t matter if you run the neg. cable of the 2nd battery to either the primary ground, OR to the frame?
  6. PlowVA

    PlowVA Senior Member
    Messages: 210

    I ran mine neg - neg, just because it was easier. Works fine. Used it for the 12 incher we had a couple weeks ago and lights didn't dim as much. Definitely going to upgrade my alternator when I get the chance.
  7. SnoFarmer

    SnoFarmer PlowSite Fanatic
    from N,E. MN
    Messages: 9,883

    I also hooked up a wire going from the 2nd battery to ground, it can be to the fender, frame, engine block, besides the wire going to the primary battery. It may not make any difference, I just wanted to have a good path for the flow of electricity,
  8. Garagekeeper

    Garagekeeper Senior Member
    Messages: 459

    Heres what we do on duel battery hook ups, we run the positive battery cable to the second battery and the ground cable to the engine. And then add an additional battery cable from the battery to the frame of the truck, that will make sure that you get full battery current to anything that may be using the frame as its ground.
    Just remember to be sure to clean the mounting points up really well, you can use external/external star type lock washers as the manufactures do under the connections to improve the connection.
    :rolleyes: John...
  9. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    easily half the 12 volt problems we see, in every kind of electrical situation are bad grounds in something, somewhere. Grounds, Grounds, Grounds, everywhere, and clean your existing grounds.
  10. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Take a big ground wire to the engine just to be safe. It will make sure you get good current flow and it has 2 paths to ground. Go through and make sure all the black wires bolted to the frame and engine are clean and have dielectric grease coating them. Every system depends on a good ground:engine, Lights,gas gages/pumps,computer and emissions systems.
  11. danno

    danno Senior Member
    Messages: 401

    I don`t know. Some say run neg. to neg. Others say run second battery neg. to frame and/or engine. :dizzy:
  12. justme-

    justme- 2000 Club Member
    Messages: 2,138

    Well, look at it rationally and logically- where did the manufacturer of the truck run the ground from the battery THEY installed?

    Odds are to the engine and there are several ground straps running from the engine to the frame so the frame is ground too, right? So why does it matter if the second battery it grounded to the 1st battery, the frame OR the engine? Electrically it doesn't. The truck, battery and electrons don;t know the difference. The only consideration is if the grounding straps between the engine and frame are corroded you have electrical problems- that's the same for any number of batteries.

    Dodge ran the ground from one battery to the alt bracket and the other to the frame on my Ram because that was the easiest place to tie it.

    It don't matter, do which ever is the easiest connection and costs the least amount for new neg cables.
  13. hesko1

    hesko1 Member
    Messages: 45


    neg. to neg. on the batteries. Also, from each battery, run a ground to the frame, engine, and body. I know this seems like overkill, but we are plowing snow! in the worst conditions possible ! You can never have to many grounds!
  14. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Another thought: You have double the battery why not double the path to ground. If the first batteries ground cable has a problem you still have the second one connected to the engine.

    If this truck is just used for plowing (sits waiting for snow) think about having a way to disconnect the batteries from each other. If you don't you get what's called
    "Battling Battery Syndrome" The stronger battery discharges into the weaker one trying to equalize the voltage. This goes back and forth till they both reserves are reduced.