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Billinwoodland's avatar
Billinwoodland
Explorer
Aug 21, 2015

wire size, 4 6v batteries in series

Hi folks. In anticipation of some boondocking this fall, i'm upgrading my battery bank from 2 6v to 4 6v in series. I have a Monaco Monarch on the ford chassis, and have room for the additional two batteries in the battery compartment. From my reading, it looked like the appropriate cable size for this addition was 4/0 size wires. I was going to have all new cables made to help eliminate any voltage loss from unequal cable size and length. I just came from my local NAPA auto store who usually are much more knowledgeable than the other chain auto parts stores, and they told me the 4/0 size cable was huge and not needed for my application. I'm no expert, what say you?
Also, should these be copper wires? I'm wondering if I can just go to home depot and buy the wire and connectors and make them myself. Thoughts?
Thanks
Bill
Class A

26 Replies

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  • donn0128's avatar
    donn0128
    Explorer II
    Aug 21, 2015
    Go to a welding store, buy sufficient length of welding cable and then at a decent electrical supply house and buy some solder lugs in the right size. At home cut the cables to length and using a propane torch solder lugs to cable. Now, you have battery cables big enough for any situation.
  • 2oldman's avatar
    2oldman
    Explorer II
    Aug 21, 2015
    Billinwoodland wrote:
    my mistake, its a 12v system. I do have an inverter, but it is the portable variety.
    Thanks.

    Ok, that's a small inverter then, right? The 'correct' way of sizing the load cables to your coach is determined by the largest amp draw expected, and we don't know that either.

    The interconnect wires on the batteries can be 50% smaller.

    As an aside, it's unusual to upgrade to a large bank size sans inverter, as 2 batteries are usually sufficient to handle 12v loads and a small inverter.
  • Billinwoodland's avatar
    Billinwoodland
    Explorer
    Aug 21, 2015
    sch911 wrote:
    Hopefully you mean 4 six volts in series/parallel (2 pairs) right? 4 six volters all in series would give you 24 volts!

    my mistake, its a 12v system. I do have an inverter, but it is the portable variety.
    Thanks
    Bill
  • sch911's avatar
    sch911
    Explorer
    Aug 21, 2015
    Hopefully you mean 4 six volts in series/parallel (2 pairs) right? 4 six volters all in series would give you 24 volts!
  • 2oldman's avatar
    2oldman
    Explorer II
    Aug 21, 2015
    Billinwoodland wrote:
    I just came from my local NAPA auto store who usually are much more knowledgeable than the other chain auto parts stores, and they told me the 4/0 size cable was huge and not needed for my application. I'm no expert, what say you?
    I'm somewhat of an expert! Answering this question without knowing how you use your batteries is folly.

    First, large cable is usually recommended for large inverters. Do you have one of those?

    And, 4 6v batteries in series is 24v. Is that what we're talking about? I doubt it, but it needs to be asked, and you don't want to pump 24v into your 12v systems.

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