Should I replace my cart batteries?

bc buck
bc buck Registered Users Posts: 59 ✭✭
in General Solar Power Topics #1
I posted this in June-
   
While doing maintenance I noticed positive terminal side of all 4 of my wet 6 volt cart batteries slightly bulged. They where put on line January 2017 and not abused. Only get about 50 50% discharges a year. Did get down to -15f once this winter but should have been fully charged. Also batteries seem to still hold close to new on the AH.

Now with full charge was not able to run microwave and thought something was up. Tested all 4 batteries with hydrometer and found one center cell not reading. All other cells test like new. Is it safe to run this bank or should I replace all 4 cart batteries. Was hoping to get another year out of these to give me time for research into lithium upgrade.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,634 admin
    #2
    Are these batteries in series or parallel?

    The battery with the cell near 1.00 SG, it is not doing you any good (the "Dead" cell is not supplying voltage to that string--And depending if it is "open or shorted", may also be under/over charging the rest of the cells/batteries in the string). If these, were for example "cheap" Golf cart batteries, you may want to replace the one with the dead cell for $100 +/- and if this lasts 1-2 years--And you are happy--Then why not (it is always possible for another cell/battery to fail down the road--No guarantees here).

    3-5 years is good for Golf Cart/Lower cost Lead Acid batteries... In cold regions you may get as much as 7+ years.

    The positive terminal "bulge" is common as FLA and AGM batteries age. Don't think the -15F hurt anything.

    May also be time to review charging for bank. Do you get 10% rate of charge? Or at least >=5%? Do you get the batteries "on charge" after discharging (don't set at less than 75% State of Charge before recharging)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • bc buck
    bc buck Registered Users Posts: 59 ✭✭
    #3
    This is 4 6 volt batts in series parallel. These are from Sams and cost about $100 each 4 years ago. Thought would have had more life out of these because they where not abused. Maybe Missouri 4 summer months over 80+F shortens there life. I dont think I want to add a new battery to the other three with them bulging also. I guess I need to see if the one with a bad cell has any voltage output. If It does maybe limp along like it is or drop those two in series and see how many AH I can get out of the other two.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,634 admin
    #4
    Measure the voltage across the battery with the "dead" cell... If the voltage is higher (than its other good mate)--It means the cell is open and not affecting the rest of the bank--Other than supplying little current/energy to the loads.

    If the bad battery is low voltage, it can be sinking current during charging--Over charging its mate (over heating, using too much water, gassing too much, etc.), and possibly limiting charging to the other parallel "good strings". And will not supply much "useful" current until the battery bank is near 10 volts (i.e., other batteries are "dead").

    In any case--disconnecting that battery/string is probably the best bet.

    In general, the rule of thumb for battery aging (not talking about cycling life here) is: For every 10C over 25C (18F over 77F), the batteries age 2x faster... 80F bank is not that hot (vs 77F standard temperatures). Conversely, for every 10C under 25C, the batteries have 1/2 as fast. This accelerated aging only occurs when the batteries are "hot" (i.e., 95F for 3 months of summer, they have "lived/aged" 6 months).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #5
    I think that I would give it a try with a new sams club battery . 
     Its easy to have one bad cell  in 12 
    you mite get a year or so out of it. 

    (  Another thought )
        Sams club sells a lot of battery’s  and people are returning there old battery’s for the 5 dollar core charge . 
     I’ve seen a pallets of battery’s going for recycle . 
     And they have lots of there gc series  stacked up . 
      People replace a bank when one or 2 battery’s  go bad  in the bank  I’m sure there are usable  battery in the stack
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,174 ✭✭✭✭
    edited September 2021 #6
    Wellbuilt has a point, but I will add that a golf cart shop would likely be your best source if you decide to go that way.
    I always have more questions than answers. That's the nature of life.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #7
    wellbuilt said:

    (  Another thought )
        Sams club sells a lot of battery’s  and people are returning there old battery’s for the 5 dollar core charge . 
     I’ve seen a pallets of battery’s going for recycle . 
     And they have lots of there gc series  stacked up . 
      People replace a bank when one or 2 battery’s  go bad  in the bank  I’m sure there are usable  battery in the stack
    FWIW - I think the core charge was $18 last time I was there for golf cart batteries. Oddly they don't require a GC battery in exchange and the core charge for car batteries was less.(old info but I used a tiny lawn tractor battery as an exchange)

    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.
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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #8
    I’m not really sure what they are doing with the core charge ? 
     I use a lot of these for GC and solar .
     Some times the core charge is 20 but I’ve payed 5 $ and I’ve bought a bunch with no core charge ? 
     Most guys that change out there own battery’s buy from sams club , and they return the battery’s at sams club 
     so you can get a good battery at Approximately the same age and same condition as what you have allready .
     My battery’s go to a recycler when they are paying top dollar $$$$ I get 45 bucks some times for a big battery
     
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,174 ✭✭✭✭
    #9
    wellbuilt said:

     My battery’s go to a recycler when they are paying top dollar $$$$ I get 45 bucks some times for a big battery
     

    We were getting $0.45/lb not too long ago, but I can't get over $0.30/lb. now. I suspect that the price varies regionally. 
    We don't collect core charges for our batteries because neither Concorde nor Fullriver requires it. On large projects for lots of replacement batteries, I do stipulate that I have the salvage rights to the old lead-acid batteries.
    I always have more questions than answers. That's the nature of life.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    #10
    Marc Kurth said:
    wellbuilt said:

     My battery’s go to a recycler when they are paying top dollar $$$$ I get 45 bucks some times for a big battery
     

    We were getting $0.45/lb not too long ago, but I can't get over $0.30/lb. now. I suspect that the price varies regionally. 
    We don't collect core charges for our batteries because neither Concorde nor Fullriver requires it. On large projects for lots of replacement batteries, I do stipulate that I have the salvage rights to the old lead-acid batteries.
    Wow! I thought I struck gold when I got 38 cents a pound for my last bank.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,174 ✭✭✭✭
    #11
    Thirty-eight cents is more than I have seen in a while! It really adds up when it involves a large battery bank - or a municipal solar lighting changeout.
    I always have more questions than answers. That's the nature of life.
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