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Installed dual batteries is this ok?

Discussion in 'Truck & Equipment Repair' started by green frog, Jan 3, 2010.

  1. green frog

    green frog Senior Member
    Messages: 246

    I have a napa legend battery with a 1050 cca and added a napa legend 695 cca due to size its what fit. Is that ok? I have them wired ground to ground and power to power. They are in a 1995 F250 which had a 95 amp alt and over the summer I put in a 130 amp alt. I did some research and see some guys ground the 2nd battery to the frame. Which is the correct way? It seems to be ok but the last 1 to 2 hours of plowing there is still a bad draw like the batteries are not keeping up. Am I ok or do I need to change something?
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    It's not ok to run two completely different sized batteries tied directly together and grounding to the frame isn't a wise idea either unless you also increase the size of the frame to main battery or engine ground.
  3. Eliw

    Eliw Member
    Messages: 30

  4. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

  5. Nasty-Z

    Nasty-Z Senior Member
    Messages: 370

    Yes , the batteries should be of the same make , size , and capacity, and ideally the same age . What will happen with one larger battery is it will try to equalize with the smaller one and charge /discharge at different rates .

    As for you charging problem, I would check and double check the grounds and power wires , make sure there is a heavy gauge charge wire from the alternator to the batteries and the same or larger size wire from the engine to the batteries .

  6. naturalgreen

    naturalgreen Senior Member
    Messages: 404

    it is complicated but the batteries will compete and draw against each other and ruin everything.
    check in searches there are pages of why. Electricity may seem to work similar to water if you want to simplify it but batteries and electricity in a vehicle is a complex thing. you will actually ruin you battery and could cause damage to vehicle. as far as ground definately read those past posts it is the most important part and should be done correctly. Shortcuts cost in the end. If only a small battery fits get two of those and fix ground and you are on your way.
  7. Bugs

    Bugs Junior Member
    Messages: 5

    Green Frog,

    Can you please post a picture of where you located your second battery in your 95 Ford? If you have no picture, please explain where your mounted it. I understand how to wire it, just looking for best place to mount. I have the same truck.
  8. Sears Diehard Plantinum

    Get one good battery and dont worry
    This is my third season and this battery is amazing
    I had duals in the 92 but there was no room in the 95 Bronco and this solved the problem
    12-14 hours each run and we have had 7feet of snow so far this year

    btw: large cable to alternator and same from neg to alt ground -- Jerre's best idea