44 or 51 amps

ingoldsby
ingoldsby Registered Users Posts: 19 ✭✭
in Off Grid Solar & Battery Systems #1
Good morning  everyone     I would like   to ask if anyone would  no what my bulk amps should  be    my system  consists  of   8 . Surrette ss550 6  1 string        mag 4448 pae  inver charge     pt 100 mmpt   120/ 240    48 volt    max chargeis at 70 %   which is 44 amps     should  be   raised  80%  is 51 amps   or 90% ????                   thanks  for you help  cheers
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #2
    It seems to me those batteries should be able to take ~60a.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • ingoldsby
    ingoldsby Registered Users Posts: 19 ✭✭
    #3
    Thanks for your input my fine freind    come to think of  my last 2 batteries  on end of string always seems to be lower in sg   maby I haven't  had the max charge rate  set properly    I will change  amps  thank you  
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #4
    Are you running a battery temperature sensor on your charge controller (if it has the option)?

    More or less, keeping track of the battery temperature is as (if not more) important as your concern over the maximum charging current.

    If your charger cannot measure battery charging current (vs the total DC loading of battery + your loads), limiting your charging current can be an issue--Especially if your loads are during the daytime solar peak (i.e., water pumping, cooking, computers+working+printing, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • ingoldsby
    ingoldsby Registered Users Posts: 19 ✭✭
    #5
     Thanks  again for the reply   . B.B,       my charge  contrller   is a pt 100 magn  I have the temp sensor  that  came with inverter  ,  also bmk       temp right  now is 62 far  is that good ?  Winter is here in ontario   my crawl space houses batteries  summer temp doesn't  get above 69 is that good?    Thanks man
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #6
    The temp sensor, when properly connected to the controller and batteries, will adjust absorb charging voltage up (if cold), or down (if warm). As Bill said, getting that voltage right is really more important than a current limit. A cold bank will have a lower effective capacity, need higher absorb voltage, and tolerate lower state of charge for longer. Not really "good", just different.

    I haven't tried it, but I'm not sure a FLA battery will take enough current in bulk to hurt it. I'm always limited by PV or generator current, so I set limits based more on my sources than the limit of the bank. Given unlimited current though, I'd limit ~15-20% of ah capacity. In your case ~60a.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • ingoldsby
    ingoldsby Registered Users Posts: 19 ✭✭
    #7
    Right on  thank you for feedback ,  again  really appreciated . I  have set  current  to 57 amps     and charged  today with gene 7000 honda     go to 60 absorb    100% soc      after   1  . 1  /2      hour tapers down to  6  or 7 amps  I guess depends on batteries temp   which in the  morning  is 59 f        when charge 100%    doesn't  exceed  62 f         does that seem   good to you Estragon   ?...
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #8
    Sounds about right to me. 6a is ~1.5% of capacity, a reasonable current to end absorb. Presumably ~60v for absorb - about right for those batteries.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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  • ingoldsby
    ingoldsby Registered Users Posts: 19 ✭✭
    #9
     That's great   again thank you    for sharing your knowledge      Happy Holidays 
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