checking my battery banks SG this AM, and have a ?

rgearhead
rgearhead Solar Expert Posts: 38 ✭
in General Solar Power Topics #1
Was checking water levels and taking SG readings, battery temp is at around 70 in my cool garage, and was getting readings of 1,300 on most cells and like a hair under 1,300 on 2 cells....

Is it ok to have them reading this high ??

the battery's are new in service, but sat on a skid for almost a year till i got to them...

thanks....
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #2
    Re: checking my battery banks SG this AM, and have a ?

    Have you checked the calibration of your hydrometer? Also be very careful that there are no gas bubbles stuck to the outside of the float.

    You can do the calibration by (carefully) mixing a standard solution of acid by adding concentrated acid to water. I will not go into all of the details of this, since the information is available.
    SMA SB 3000, old BP panels.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #3
    Re: checking my battery banks SG this AM, and have a ?

    rgear..,

    And in addition to what inetdog has mentioned, Do you know the target SG for your batteries?

    What brand/model # of the batteries?

    If you have a way of recharging the batts, often, batteries need to be cycled to 80% State Of Charge (SOC), or below a few times to help them settle down. Some manufacturers recommend a commissioning procedure for new batteries.

    Have these batteries been kept charged, periodically?

    And, regarding Hydrometers and bubbles inside of them, please always flush Hydrometers several times with Distilled Water after each measuring session -- this helps keep any sticky residue from building up inside the Hydro. This residue allows air bubbles to stick to the float, and the inside of the tube or chamber of the Hydrometer.

    IMO, the best Hydro to use is one that has a glass tube, with a glass float inside.

    Try to avoid any plastic Hydro with a pointer float, as these often do a very poor job, in general.

    FWIW, YMMV, 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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  • rgearhead
    rgearhead Solar Expert Posts: 38 ✭
    #4
    Re: checking my battery banks SG this AM, and have a ?

    Battery's are sam's club deep egc2
    http://www.samsclub.com/sams/duracell-golf-car-battery-group-size-egc2/prod3590220.ip?navAction=push

    my Hydro is the all glass with a built in temp compensate gauge, and i do flush and clean it after use, this is a actually only the second time I have used or checked these battery's, last time was early spring and it was pretty cold in the garage and I was only getting around 1260 sg in the cells, why I was kinda shocked when i checked today and almost had 1,300 across the board ....

    the battery's sat for a year on a skid (not being charged ) till i got around to them, and I just recently (4 weeks) got them charging off a 250 pv with a tri star mppt 45, as for discharge'' I only use the bank on the weekends to run a floor fan and a few lights in the garage, voltage is usually down to 12.5 at the end of the day while still under draw...
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #5
    Re: checking my battery banks SG this AM, and have a ?

    There was a time That I thought that the SG's wouldn't go above the fill strength unless it was skewed by battery temperature with a severe overcharge. I now believe that the acid used in the paste on the positive grid when it is formed will allow the SG level to go above the fill SG. Most of my battery banks just happen to be Sam's GC-2's and I see them at 1.275 -1.280 often under normal charging. Could I be fooled that they always had something above 1.265 as the original fill ??, I guess.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #6
    Re: checking my battery banks SG this AM, and have a ?
    Blackcherry04 wrote: »
    There was a time That I thought that the SG's wouldn't go above the fill strength unless it was skewed by battery temperature with a severe overcharge. I now believe that the acid used in the paste on the positive grid when it is formed will allow the SG level to go above the fill SG. Most of my battery banks just happen to be Sam's GC-2's and I see them at 1.275 -1.280 often under normal charging. Could I be fooled that they always had something above 1.265 as the original fill ??, I guess.
    Maybe.
    Also, though, if you let your batteries gas for a long time at a very slow rate you will just electrolyze the water and will not drive off an acid mist.
    The result is that until you top off the cells with distilled water you will have a higher SG solution than you could get to via normal charging.
    Was the fluid level in the cells low compared to the initial fill?
    Also, as you noted, if you put full strength electrolyte into a battery that is at partial charge, the end result will be a full charge SG which is on the high side of normal.
    SMA SB 3000, old BP panels.
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  • rgearhead
    rgearhead Solar Expert Posts: 38 ✭
    #7
    Re: checking my battery banks SG this AM, and have a ?

    haven't had to add water yet, checked all cells levels and there good....
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