check my battery wiring

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Cpfarr
Cpfarr Registered Users Posts: 19 ✭✭
in Off Grid Solar & Battery Systems #1
hey gang,

wanted to have everyone take a look at my battery bank wiring to make sure I have things right. let me know if you think i should do things different.

The bank is made of three strings of 8, 6v for a 48 v system

string 1= battery 1-8
string 2= battery 9-16
string 3= battery 17-24

because of my buildings layout, I'm stuck with a row of batteries as the diagram shows.

As always thanks, Chad
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: check my battery wiring

    Chad;

    I can't see that clearly on my tiny netbook, but it looks a tad messy. I'll throw the standard Smartguage wiring link at you :phttp://www.smartgauge.co.uk/batt_con.html

    With three parallel strings it's time to think about busbars. Very important to get the wire lengths on each string equal to maintain even current flow to/from all batteries.

    Heck, you may have it right: but it's only a 2" picture on my screen! :cry:
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #3
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    Re: check my battery wiring

    It appears to be a balanced wiring...

    You should have a fuse or breaker on each parallel connection point to each series string. You have appropriate gauge wiring for the peak current and voltage drop for the inverter and charger?

    And I would get an AC/DC Current Clamp Meter so you can monitor each string to ensure that current is is balanced when charging discharging.

    Are you going to add a battery monitor?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cpfarr
    Cpfarr Registered Users Posts: 19 ✭✭
    #4
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    Re: check my battery wiring

    Thanks guys!

    Bill, what is the purpose for the fuses between each string? Not arguing I've just never been taught why they are important.

    Thanks
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #5
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    Re: check my battery wiring

    If you have there or more parallel strings of batteries or solar panels, if you get a short in one string, the other two strings can supply enough current to melt the wiring in the first bank.

    Also lead acid batteries have the ability to output huge amounts of current into a dead short. The fuse/breaker will protect the wiring from the battery.

    With a car battery, it was assumed the cable to the starter was heavy enough to survive a dead short long enough to drain the battery.

    With large battery banks for of grid power systems, the battery banks are more than large enough to fuse the interconnect cabling in most setups.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Cpfarr
    Cpfarr Registered Users Posts: 19 ✭✭
    #6
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    Re: check my battery wiring

    Thanks Bill. That was what I needed to know. I was thinking of it in terms of auto batteries instead of the ones were dealing with. What do you recommend as far as accomplishing the fusing? Do you have a tried and true that you suggest? I'm running 4/0 cable between each string and to the inverter and 2/0 cable between the batteries in each string. Sorry i forgot to answer you on my last post.

    Thanks, Chad
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #7
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    Re: check my battery wiring

    Talk with whomever you will be purchasing your hardware from...

    In general, a couple good places to start:

    High Amperage Inverter Fuses & Breakers

    And here are some smaller circuit breakers.

    Our host does not sell these--but they are really neat fuses for battery strings--both one and two fuse versions.

    Figuring out if you are going to use cut and stripped cables or swaged fitting on your cables will affect your choice in fuse/circuit breaker hardware too...

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