Battery Cable Gauge and Type

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porch13
porch13 Registered Users Posts: 68 ✭✭✭
in Off Grid Solar & Battery Systems #1
I'm getting ready to upgrade my batteries for my little palace in the woods with a pair of the Crown 305Ah batteries. These batteries have dual terminals, with one being the standard, automotive type connector. I'd like to use those terminals to connect the charge controller to the batteries, leaving the other terminals free for the other assorted wires. My question is....is there any reason why good quality Napa 4 AWG battery cables wouldn't work? The cables would see about 30A max at 12v.

Thanks guys!
Northern Arizona...4050 Watt off-grid system - Outback FP1 - Rolls 605 in a 48V bank
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
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    Re: Battery Cable Gauge and Type

    how is it presently connected? any buss bars?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • porch13
    porch13 Registered Users Posts: 68 ✭✭✭
    #3
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    Re: Battery Cable Gauge and Type

    Right now the existing batteries are connected to the controller with 6 AWG (I think) with hand crimped 3/8 ring lugs on the end. It seems like I could get a much better connection with the big old lead automotive connector. I looked at going with 2 AWG, but the cables will only be a few feet long so I think the 4 gauge should be sufficient given what will be flowing through them.
    Northern Arizona...4050 Watt off-grid system - Outback FP1 - Rolls 605 in a 48V bank
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #4
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    Re: Battery Cable Gauge and Type

    you should base the cable size on the manuf. recommendations, as a minimum... so pick your inverter first then decide on cable size, keeping the length to a minimum...

    hth
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • porch13
    porch13 Registered Users Posts: 68 ✭✭✭
    #5
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    Re: Battery Cable Gauge and Type

    I'm using the manufacturer recommended 2 gauge wire from the battery to the inverter. The charge controller documentation calls for 4AWG but will take up to 2AWG. In looking at the voltage drop over the 3 feet between the batteries and controller, the difference between 2 and 4 gauge was minimal so I was hoping to go with the 4AWG because I have a few tight turns to make.
    Northern Arizona...4050 Watt off-grid system - Outback FP1 - Rolls 605 in a 48V bank
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #6
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    Re: Battery Cable Gauge and Type

    this is where buss bars come in, you use the 2 ga to the BB: then 4 ga to the CC and you can have 2 ga to the inverter, both connected to the BB.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #7
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    Re: Battery Cable Gauge and Type

    From 30A Charge Controller, to the batteries, you should be OK with 4ga cable. 99% of the time, at dawn, the PV's will start charging at low amps, and then by the time you get to solar noon, with the POTENTIAL for 30A, the batteries will be partly charged and not sucking full power from the PV. You may get a bit of voltage drop, but for 3', it wont be too much. I think 10 ga is safely rated for 30a, so 4ga should hold up OK
    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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