Older Battery Water Usage

plongson
plongson Solar Expert Posts: 115 ✭✭
in Off Grid Solar & Battery Systems #1
I have an older set of (16) Rolls-Surrette L-16 batteries. they are 8 years old and have been taken care of meticulously. Never below 80 SOC or hammered in any way etc. I have detailed records of maintenance I've performed over the years and with a 6 week maintenance rotation, they usually need around 3 to 3.5 gallons of water. The last couple of maintenance rotations they have been needing more water with the same loading...about 4 to 4.5 gallons. Charge schedule and levels have not changed. Question: Do older batteries sometimes require more water?? They still perform as good as day one, this is the only odd thing happening. THANKS!! 
3500w solar, 800AH with Rolls Surrette, Magnum inverter, Midnite charge controller, Kubota 21kW diesel genset...private well...and just recently connected to city power for additional options...nice to have options 
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Comments

  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #2
    My L16s are ~5yrs old (used seasonally), and do take more water as they age.  IIRC, Rolls recommends somewhat high Vabs than many.  Mine absorb at 58.8v (+/- temp comp), and use ~2-3gals/6mos these days.  Initially it was <1gal/6mos.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #3
    My experience is as lead acid age they begin to use more water particularly if shallow cycled with a vigorous charging regime with long absorption periods. Because of this I actually had to reduce the bulk absorb voltage on a bank charged with a Morningstar TS 60 PWM on a lightly loaded bank or it would sit at absorption voltage, actually in PWM,  all day merely consuming water. Ambient  temperatures are high with no RTS so manual setting is utilized, at 35°C ambient,  28V for a 24V nominal bank seems to do the trick keeping SG readings perfect while minimizing water consumption, they are only 3.5 years old. Actually I'm hoping they will fail so I can replace with LiFePo4 but they are actually working extremely well, all things considered.

    Eight years is a very respetable life, if they are still performing well despite water consumption you must be doing something right, only thing that could be adjusted if nessersary, is the absorption time, particularly during summer when more sun is available. Then again every system is different, there is no one charging regime that fits all.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • plongson
    plongson Solar Expert Posts: 115 ✭✭
    #4
    THANK YOU very much for the reply's! It gives me an idea what's going on with them. The system was so well designed and has worked so well for so long, we feel like we're on city power...but then again, we're old pros at living off grid...lol. The system has not given us any problems in the 8 years of full time living here in Southern Utah. We did have two batteries STB early on an had to be replaced, but mostly it has been an amazing system.

    What do you suspect the life cycle of a battery bank like mine, properly cared for might be?? I had hoped from the get-go it might be 12 years...Am I too optimistic?
    3500w solar, 800AH with Rolls Surrette, Magnum inverter, Midnite charge controller, Kubota 21kW diesel genset...private well...and just recently connected to city power for additional options...nice to have options 
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #5
    I'm hoping for ~10 yrs on mine, so hoping for 12 doesn't seem so overoptimistic.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
    · Share on Twitter

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