Efficient bank wiring? 32 x 12v for 24v: 4 12v banks, or 4 24v, or 2 x 12v & 2 x 24v?

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  • mevsmyself
    Junior Member
    • Oct 2016
    • 1

    Efficient bank wiring? 32 x 12v for 24v: 4 12v banks, or 4 24v, or 2 x 12v & 2 x 24v?

    Before you answer please understand my question. I know that final voltage can be 24v no matter which way I wire them, but when discharging and recharging will a different combination of wiring help increase efficiency? 32 x 12v batteries (final voltage 24). I am planning on wiring them in 4 x banks of 8 batteries each. I was thinking of basically making each bank of 8 batteries like this:8 x 12v down to 4 x 24v batteries and then connecting the 4 24v cells together to make a total of 8 batteries for 1 bank 24v. Hope this makes sense.
    My main question is about building a better bank. Would wiring 8 x 12v batteries to 12v making each of the 4 x banks 12v then wiring those 4 banks to make 24v.?? Or 8 x 12v wired at 24v then wiring the 4 banks to 24v?? I am thinking that the batteries stepping up and down in voltage depending on where in the wiring harness could allow electricity to flow more efficiently. Or handle the amps better going in and out. I have only basic knowledge, but have read that the more solar panels the higher voltage set up is desired so it is easier on the batteries. Something like that.
    If anyone knows what I am talking about please chime in, I am about to wire these batteries as soon as possible and set up my panels. Thanks!
  • inetdog
    Super Moderator
    • May 2012
    • 9909

    #2
    For more information on connecting batteries in parallel, see this helpful site: http://smartgauge.co.uk/batt_con.html

    But your first step must be to realize that putting 16 two battery sets in parallel to produce a large 24V bank is a very very very poor design. With that many batteries or battery pairs in parallel the current distribution during charging and discharge will never be well balanced and the battery life will suffer as a result.

    It is also possible for a single cell failure in one battery to produce a catastrophic fire unless you include a complicated system of individual battery fuses.

    Instead of 32 12V batteries at, say, 120AH each, you should consider a much smaller number of 2V batteries at more like 700AH each. You would put 12 of them in series to get 24V. If you have to go to two parallel strings to meet your power needs, at least that will be far better than 16 parallel units.

    The detailed way you subdivide the groups of batteries to make your parallel system has very little effect on the functionality of what is a bad idea in the first place.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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    • mevsmyself
      mevsmyself commented
      Editing a comment
      Thanks for the input. I should add that I already have these batteries and would like to use them. They are very small 12v 8 ah. Maybe not ideal, but I assume it should work.
      Also a fire danger, would it not be a danger with any battery bank? I understand more batteries increases the odds of it happening, but any bank has a possibility of fire due to failure I assume.
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