Old and new

Chris11Chris11 Registered Users Posts: 124 ✭✭
I have a 7 year old set of 4 Costco 6 volt GC bats.  I bought a new set of 4 Costco GC last year.  I asked on here about being able to parallel the old set with the new set and I was given the green light.  They have all worked nicely together for the last year.

My question now ....

Can I series them all and run 48 volts?  I do have a new 48 volt inverter so other than making up a couple of new wires, can I use old bats and new in series?

Thanks you.  Chris


  • PhotowhitPhotowhit Solar Expert Posts: 5,658 ✭✭✭✭✭
    I would not have recommended buying new batteries and mixing with old in the first place. I would have just run the first set into the ground before buying new.

    I certainly would NOT put them in the same string. If you go back to your thread asking, about adding old to new (as I did, to see if I had replied), Bill replied that way in your first response.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Chris11Chris11 Registered Users Posts: 124 ✭✭

  • RCinFLARCinFLA Solar Expert Posts: 1,399 ✭✭✭✭
    Old and new parallel strings just has variance in current sharing between old and new stacks. Do not cross strap middle cells between old and new, keep as totally separate series stacks that are top connected.

    Old and new in series has battery voltage variance, vs load/charge current, in the series stack.  For charging it can mean some bateries get overcharged, others undercharged.  Net result is battery damage.
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