Charge controller showing inaccurate state of charge

K1ngN0thing
K1ngN0thing Solar Expert Posts: 27 ✭
in Off Grid Solar & Battery Systems #1
My MorningStar Tristar TS-45 PWM is showing 0-35% SoC for my battery, even though it's at 12.6v or ~80%. I'm not sure how to fix this.
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    ancient proverb: Man with 2 watches never sure what time it is.
    in your case, you have the volt meter in the tristar and the meter in your hand, Which one is really right ?
    Can you tell us what your loads are ? How much solar ? Size of battery bank ?
    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

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • K1ngN0thing
    K1ngN0thing Solar Expert Posts: 27 ✭
    #3
    I don't even have a volt reading on the controller (didn't spring for the add-on). I have a 100w mono panel and a 125ah agm battery.VMax say the battery comes 80% charged, which checks out with the 12.6v reading.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    12.6 volts--Is that the battery resting at room temperature after a few hours of no load/charge?

    What voltage is the battery reaching during the middle of the day charging? Is it getting ~14.5 to 14.7 volts or so and being held there for 2-4 hours per day?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • K1ngN0thing
    K1ngN0thing Solar Expert Posts: 27 ✭
    #5
    That is the resting charge. It's been in the sun for a few hours now and it's the same. It doesn't look like it's being charged at all. I made the mistake of not testing my panel before mounting. Is there a way to test it after the fact? Can I measure the output at the end of the wires?

    EDIT: I just put the positive and negative ends of my meter on the positive battery and positive solar terminals on my controller, and got a reading of around 33 volts. Does this show that my panel is producing output?

    I've also randomly been getting the R/Y - G/Y fault sequence, and after following this flowchart: http://support.morningstarcorp.com/wp-content/uploads/2014/07/TS.TST_.RY_GY_Fault_Flowchart.01.EN_.pdf leads me to believe I might have a faulty controller.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    Voltage sounds ok.

    Next cover or put panel in shade. Set meter to 10 amp full scale and connect to leads of panel.

    Put in full sun and read short circuit current on full sun. (Assuming Isc of panel is less than meter full scale).

    If both Voc and Isc are ok, then 90% chance panel is ok.

    -Bill

    Ps, remember Isc is proportional to amount of direct sunlight. Isc is full sun current.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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