Specific gravity, temperature and cell position

cosmicray
cosmicray Registered Users Posts: 24 ✭✭
in Off Grid Solar & Battery Systems #1
This morning I finished an overnight charge on my 6-month old pair of GC-2's (210 Ah private labeled).

6.5 hours at 14.2V and 8 hours at 13.6V. The overnight low was 50F, which coincided with the 8 hour finish at 13.6V.

I then let the batteries rest for 3 hours. After the rest, both batteries showed 6.5V on the meter. When I checked the SG, the outside cells (all 4, 2 per battery) showed 1.275, while the center cell read 1.28 (or possibly a bit higher).

Is this an effect of the center cell being slightly more insulated from the 50F low this morning, or is this something to do with the design of the battery ? The center cells also have no large terminal attached to them.
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Comments

  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #2
    Re: Specific gravity, temperature and cell position

    They sound perfectly normal, having a .05 of spread is about as good as it gets most of the time. You could be correct about the temperature, but there probably 10 other things it could be. Even with 2v cells there always some difference.
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  • cosmicray
    cosmicray Registered Users Posts: 24 ✭✭
    #3
    Re: Specific gravity, temperature and cell position

    What made be wonder about insulation, is the Ford Transit I purchased last year has (what appears to be) an insulating blanket around the battery. Never seen that before, but as I learn more about battery chemistry and various factors, it makes sense.
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  • scrubjaysnest
    scrubjaysnest Solar Expert Posts: 175 ✭✭✭
    #4
    Re: Specific gravity, temperature and cell position

    The insulating blanket is because of high under hood temperatures. According to some battery suppliers it doesn't help much in the south.
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