I too need help with loss of battery storage.

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  • LndSchneid
    LndSchneid Registered Users Posts: 31 ✭✭
    #62
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    Hello again Bill,
    I hope these last few months have gone well for you.  A flurry of activity here and a parental passing have occupied me.  

    I have been heartened by your previous approval of our set up as it was, and when I checked this morning to see what the percentage was I was a bit mortified to find it 43%. Especially given the fact that we're running everyday at 100% with surplus.  I know you mentioned that wasn't preferable so I keep trying to add on things to lower it, but I just don't have enough amps during the day.

    I have a list of nighttime use with as much info as I could compile:

    Low wattage LED lights run for 1-2 hours, three to six of them.

    Cell phone charger, almost all night.

    Piano heater, 24/7  25 watt

    Chest freezer, kilowatt hours per year - 251 --but set higher to serve as refrigerator 

    Cell signal booster - 1 AH


    Any ideas on how to keep more a.m. battery power?  Winter is around the corner.

    Thanks again.

    Linda



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  • BB.
    BB. Super Moderators, Administrators Posts: 33,440 admin
    #63
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    Hi Linda,

    I am surviving...

    Looking at your night time loads:
    • 9 Watt lamps * 2 hours * 6 each = 108 WH
    • 1 Watt * 18 hours per might = 18 WH (probably 1/4 that much in reality)
    • 25 Watt piano heater * 18 hours = 450 WH
    • 500 Watt (est chest fridge load) * 2/3rds (over night) = 333 WH 
    • 1 Amp (cell booster) * 12 VDC (guess) * 18 hours = 260 WH
    • 20 Watts (AC inverter tare losses) * 18 hours = 360 WH
    • Total Watts overnight = 1,529 WH overnight
    • 1,529 WH * 1/0.85 AC inverter eff * 1/12 volt battery bank = 150 AH @ 12 volt DC battery bus loading (overnight)
    • 150 AH load / 1,950 AH battery bank = 0.08 = 8% load overnight
    So, your system should not be "dropping" like a rock overnight... Maybe 10% or less. Looking at the post you made a few months ago, that was a good charge (14.7 volts for ~3-4 hours absorb cycle).

    I would suggest you look at each battery in your battery bank. Take the DMM (digital multimeter) and measure the voltage across each battery (in the evening under load, and sometime during the day when charging). Assuming 6 volt batteries, you should see something like 6.3 volts (evening) and ~7.3 volts when charging after 12pm (sunny day).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • LndSchneid
    LndSchneid Registered Users Posts: 31 ✭✭
    #64
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    Thank you. I will pass that onto my handyman.  What might the remedy be if dropping like a rock can be avoided?

    Glad you are surviving.  That usually means life's challenges have us in their grip.

    Linda
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,440 admin
    #65
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    I fear your battery bank is having problems.

    Insufficient charging was an issue. Causes battery sulfation.

    Could also be bad or dirty wring connections.

    Could also be one or more bad cells...

    It feels like sulfation (relatively fast charging and very fast discharging).

    If so, that would generally need a new battery bank.

    If you are needing a new bank, then I would suggest looking at your whole off grid system vs your loads. And a backup generator for winter.

    A 1,950 AH 12 volt battery bank is just not a good design in general.

    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • LndSchneid
    LndSchneid Registered Users Posts: 31 ✭✭
    #66
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    Well that's disheartening.  I will pass along the information.

    Linda
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