My poor batteries...

timmartintimmartin Registered Users Posts: 2
So we had some gray/cloudy days as winter starts to get near... so as usual my battery bank wasn't getting fully charged every day like it does during the summer. I run the generator a bit here and there, but never to 100%. Finally there's a sunny day or two but even with some genny help the batteries don't get fully charged (not reaching my end-amps while holding voltage at absorb).

So finally I run the genny WHILE the sun is out and try to get them charged for many hours — but the charge amps just won't go down to 12.5 like it used to... went to ~18 and held steady. Then I realized I hadn't checked the water level in too long, sure enough the cells were all quite low (below the plates).

I filled them all up last night, and after letting them charge today spot checked the SG for a few cells. I got fair-to-good readings. But my charging curve today still bottomed out too high. It basically became a flat-line around 24 amps, but it used to regularly go down to 12!

So did I kill the batteries? or do they just need some more time and gentle handling to get back to their old performance? I figured I'd let them cycle a bit the next couple of days then maybe next weekend try again with gen+sun. Maybe even an EQ cycle to bubble/mix the acid, clean off the plates, etc.


  • mike95490mike95490 Solar Expert Posts: 9,358 ✭✭✭✭✭
    Re: My poor batteries...

    The trick is to not get behind - if you have a cloudy forecast, run the genset in the AM, and BULK the batteries, and hope for enough solar to get them part way through absorb. This might be 2 or 3 hours of morning run time. If it's a totally worthless day, just do 2 BULK cycles, a couple hours AM, and then couple hours evening, but try not to let the batteries get below 50%, you want to be able to skip a generator cycle if it's pounding rain and not have to dry your clothes afterwards.

    I've been doing 2 hours, AM and PM, this last week, trying to not get too far down, $20 of fuel is better then 90 days lost off the batteries because they went down to 30%.
    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

    gen: ,

  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: My poor batteries...
    timmartin wrote: »
    I realized I hadn't checked the water level in too long, sure enough the cells were all quite low (below the plates).

    Exposed plates? Oh Oh, this is bad, VERY BAD for the poor batteries. :cry:
    "Most batteries don't die, they're murdered."
    Time to start checking out what's available for new batteries. Perhaps a tear-jerking letter to Santa might be in order.
  • CALLDCALLD Solar Expert Posts: 230 ✭✭
    Re: My poor batteries...

    Perhaps invest in a good set of VRLA/AGM batteries? I've recently dumped flooded batteries in favour of the much cleaner looking better performing VRLA's and have never been happier with my batteries!

    Sure many purists here will quote the shorter cycle life, intolerance to over charging and inability to monitor specific gravity, but none of these bother me. A good voltmeter is all I need to estimate state of charge, my charge controller ensures they never over charge and the shorter cycle life is offset by the fact that mine were actually about half the price of an equivalent deep cycle flooded solar battery!

    Other pros I have found are a much lower internal resistencia which results in a more efficient charge/discharge cycle - 24.5v is now my new Low Voltage warning setting vs 23.8v for my old flooded set. I've never seen them ever dip below 24v even with my inverter pulling at it's maximum rated power (2500w from a 260ah/24v battery). Oh yes, and did I mention no messy SG checking or hydrogen fumes?
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