Older Battery Water Usage

plongson

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!! 

Estragon

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.

mcgivor

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.

plongson

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?

Estragon

I'm hoping for ~10 yrs on mine, so hoping for 12 doesn't seem so overoptimistic.