Lost amp hours, rolls battery

UptownNZL
UptownNZL Registered Users, Users Awaiting Email Confirmation Posts: 1 ✭
in Off Grid Solar & Battery Systems #1

Purchased a couple Rolls Batteries a few months back, had them sit extensively for quite a while  because the building I was preparing to install them into hadn’t been completed yet. Finally, Sunday June 13. 2021 I hooked them up and had them charge for 3 days under a Morningstar MPPT 60 amp charge controller, yesterday which made it day 3 undercharge while on “float” mode I decided to plug in my deep freezer, around 1:21pm eastern standard time. And roughly around 7 pm‘ish. I noticed that they were being discharged at a pretty alarming rate, they were at 11.4-11.5 volts and were headed lower, which wasn’t normally, because I use this configuration a lot. I immediately then removed the freezer and it sprouted back to 12.7 volts, this mourning I had awaken to them at 12.5 volts. They’re brand new, first time mount. 4 Rolls battery by Surrette (6 FS GC-HC), 6 volts tied in series then parallel into a 12 volt system. I’ve currently got 124 watts coming in and they’re at 13.2 volts @ 7:30 am. Was adding a load/freezer while on “float” mode the problem? Should I manual “equalize” them to see if I’d get the dedicated amp hours tonight? 

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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    edited June 2021 #2
    Hi NZL..,  Welcome to the Forum.

    Download this Surrette Battery Manual.  The software is cranky,  and does not allow pasting the ACTUAL LINK to the manual,  so paste the following term into your fav search engine,  to download the manual:
    Surrette Battery User Manual

    Pay particular attention to the battery Commissioning requirements,   and the recommended charge voltages.

    This battery appears to be a Flooded type (easily-removed top caps),  so you will want to measure the SGs of each Cell,  and record them for later reference in your battery Logbook.   Number each battery,  and use a letter for each cell.  Mark these on each battery./cell with a felt tip marker.

    Since you said that you bought "a couple"  of these batteries,  it is possible that you added the new ones in parallel with some older ones ?   Depends on your definition of "couple".   Paralleling new with old LA batteries can cause issues  ...

    Please let us know how you are doing.  Getting SGs up to spec is very important. And getting off to a gpod start is very important.
    Good Luck,  Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,637 admin
    #3
    Welcome to the forum UptownNZL,

    How long did the batteries sit without charging? In general, in a warmish climate, flooded cell lead acid batteries should be recharged at least 24 hours once a month.

    If they sit longer, they begin to seriously sulphate and die after a few months. More or less, you want to keep them >75% state of charge in storage--And a generic FLA battery will self discharge below 75% in ~1 month at ~25C/75F.

    https://rollsbattery.com/wp-content/uploads/2019/11/Rolls-Battery-User-Manual.pdf

    Deep cycle lead acid batteries generally have a minimum rate of charge of 10% for best life... Your series/parallel 6 volt @ 235 AH is a 12 volt @ 470 AH battery bank...
    • 10% rate of charge * 470 AH (20 hour rate) = 47 Amp nominal charging current
    • 47 amps * 14.5 volts charging * 1/0.77 panel+controller deratings = 885 Watt array nominal (recommended minimum full time off grid)
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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