48V battery bank help

csspring
csspring Registered Users Posts: 3 ✭
in Off Grid Solar & Battery Systems #1
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
    Re: 48V battery bank help

    Welcome to the forum.

    Your wiring is not optimal and will lead to charge imbalance in the batteries. You need bus bars.
    Look at method #3 on this page: http://www.smartgauge.co.uk/batt_con.html

    Also, you should read more about parallel batteries and buy a DC current clamp meter:
    http://forum.solar-electric.com/showthread.php?14674

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: 48V battery bank help

    It should look more like this (at least electrically).
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #4
    Re: 48V battery bank help

    It will be a little bit less messier if you orient all the batteries in the same direction.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,608 admin
    #5
    Re: 48V battery bank help

    With 3 or more strings, I would highly suggest a series fuse or breaker per string. Like these Bluesea fuse holders (fuses extra) at a minimum (breakers are very nice because you can turn of power for servicing--but even more expensive):
    Attachment not found.Attachment not found.

    I would suggest that each string's wiring+fuse be rated for 100% of your expected maximum sustained current (note: actually 1.25*100% or 125% of maximum load--NEC derating for wiring and protective devices).

    If you go with 4 or more parallel strings, You may get away with 50% of maximum bank rated current wiring (and fusing).

    Also--Each cable that leaves the bus bar should have (for safety) a fuse or breaker to protect down stream wiring in the case of a fault/short down stream. Lead Acid batteries can output 100's to 10,000's of Amperes into a dead short.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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