Advice needed on 24 volt Battery Bank Diagram Included

cdrudge
cdrudge Registered Users Posts: 5 ✭
in Off Grid Solar & Battery Systems #1
I would value input and advice on my battery bank.

Attachment not found.:::blush:
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Re: Advice needed on 24 volt Battery Bank Diagram Included

    The problem is that the center strings that is your connecting points on a post doesn't have to go the extra 48 inches, so has the least resistance. Better to have them all go to a bus bar or common point, then connect there.

    Outer strings have 80 inches of wire, inner strings have 32 inches.

    I guess you've read that having more than 2 or 3 strings is nuts?
    Just too many problems, you should have each string fused somehow.

    What happened to your FM60? Now that you are at 24 volts it should handle your <1200 watts of panels.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #3
    Re: Advice needed on 24 volt Battery Bank Diagram Included

    WOW! Like Photowit suggested, anything over three parallel strings is asking for trouble. You have 8!
    Best you can do is have equal length of cables with identical ends, all going to one common point for the + side and the same for the Neg side, then hope for the best but expect trouble.
    Good luck.
    Oh, and if these are Flooded type batteries, you have 96 cells to regularly check for SG and electrolyte levels. I find it a pain in the butt to check and water the 18 cells in my L-16 batteries, couldn't imagine having to check and water almost 100. WOW again!
    Let the fun begin.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: Advice needed on 24 volt Battery Bank Diagram Included

    If you must use more than two parallel strings you really should use common connection points/bus bars as per Smart Gauge method #3: http://www.smartgauge.co.uk/batt_con.html

    Each string should have its own post terminal fuse for safety.

    It is far, far better to use higher Amp hour batteries than to parallel lots of smaller ones. For example using 220 Amp hour 6 Volt batteries (four in series) would give 880 Amp hours @ 24 Volts with only four parallel strings. Less wiring, fewer cells to check.

    For that much battery you would want to run an FM80 or MidNite Classic as you'd want to try for 80 Amps peak charge current (about 2500 Watt array). Are you sure you need that much battery? That's like 9.6 kW hours of stored power.
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