Replacing battery bank

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oglethorp
oglethorp Solar Expert Posts: 30 ✭✭
in Solar Beginners Corner #1
Seems like it s time. My 16 6v Golf cart are failing fast. Now down to one string of 8 fairly good ones. I ve found Trogen 105 s ..6v needing 16, 8v needing 12, and 12v needing 8 to make the replacing of the 2 strings. 440. ah. Total
Question is which is the best way to go? The pricing of the 12v makes that a deal or is it really. Big gray area here so be patient pleas.
Thanx,,,
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    Re: Replacing battery bank

    1) how old are they

    2) why are they failing 8years = old age, less than 8 years, whats wrong? too low of charge voltage, not topped off often enough, not equalized ....

    3) what's your system voltage ? 24, 48?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #3
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    Re: Replacing battery bank

    And how much do you use them? Standby for emergency power? Cycle them by 25-50% every couple days? What kind of loads (how many amps, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Replacing battery bank

    I'm judging you have a 48 volt system, based on the potential replacement combinations mentioned:

    16 @ 6V = 96/2 = 48
    12 @ 8V = 96/2 = 48
    8 @ 12V = 96/2 = 48

    Your current Amp/hrs are 440.

    You need to determine which of the combinations supplies you with around 440 Amp/hrs at the lowest price per Amp/hr. So add up the Amp/hrs for each combination. Divide the cost of the package by the # Amp/hrs. Don't forget that different combinations offer trade-offs in space, wiring, et cetera. All other factors being equal (which they aren't), the 12V batteries would mean fewer inter-battery connections and probably would take up less space. Also be sure that all the batteries you're comparing are truly comparable; real deep cycle, not "Marine/RV" and preferably from the same or at least same quality of manufacturer (Trojan or Deka as opposed to "Store Brand").

    (As Mike has pointed out, providing everything is working and they need to be replaced due to age. If they are failing for some other reason, that needs to be addressed first otherwise your new batteries will suffer the same fate.)
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