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Early 90's GM factory dual batteries?

Discussion in 'Chevy Trucks' started by t_jones98, Feb 8, 2012.

  1. t_jones98

    t_jones98 Junior Member
    Messages: 2

    Was posted in the dual batteries sticky but didn't think that got too many hits.

    Two questions:
    1. If both battery's positives are connected (via 2ga of course), do you need wires running from the alt to each battery, or just the main? If both, can a single in-line fuse be used and then "Y'd" from there to each battery?

    2. The early 90's GM's with factory duals came with an isolator of sorts, solenoid type that connected from the P-side (aux) battery through the solenoid to the term block on the firewall, where the pos(+) of the main battery attaches. Looks like this is switched through the fuse block (small wires running into the cab). Should this be taken out of the equation? Should it be wired up with 4ga? Do I still need to connect to the term block in some way?

  2. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    If you just want two batteries wired in parallel for better starter/plow performance, no isolator.

    Run the alternator wire to the nearest battery only. Don't forget a 2ga ground from each battery to the frame.
  3. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,739

    Yep what 2 said. The factory ISO is kinda. Ummmmmm stupid the factory uses like 10g wire, not super smart. Just run 2g all around and you'll be fine. 2g neg to the alt as well.
  4. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Not to the frame unless you're also running a 2G engine-to-frame ground, which isn't ideal either anyway. Ideal would be all high current grounds directly on the engine, therefore that's where they ALL should be.

    Then you can add an engine-to-chassis ground (8G is plenty) just for good measure for any/all OEM components that ground through the chassis. Which will only be the tail lamps and fuel pump, but only on specific applications.

    Never use the chassis as a "ground junction block", use the engine.
  5. leolkfrm

    leolkfrm PlowSite.com Addict
    Messages: 1,337

    the factory dual batteries were set up as a camper pkg....so you did not kill teh starting battery....as mentioned some good battery cable hooking them together without the isolater will give you the result you desire