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Found some 4AWG in my vehicle! - Use it for my control board?

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  • Found some 4AWG in my vehicle! - Use it for my control board?

    Hey All,
    I'm slowly putting together my "control board" which will house the main components of the system; charge controller, inverter, battery hookup and solar hookup... It's hard to say what the system will "become" but right now I'm building around my MPPT controller which is a SolarEpic Tracer4215BN which allows for 40A in and 20A out. I'm designing a 24V 1.2Kw array and battery bank. Based on my reading on wire sizing so far, it sounds like it's hard to, if not impossible to use wire that is too thick. Is this true?

    I recently bought a used vehicle that had a hard wired inverter run from the battery. I don't have a need for it so I pulled it out and with it came about 12ft of stranded 4AWG wire. The wire is in good shape so I'm considering using it to tie together my components. Based on some number crunching I could get away with 8AWG for this system so I'd be oversizing the wire a bit here. My gut feeling says this is cool but I don't know for sure.

    Are there any pitfalls for using oversized wire?

    Side question.
    When connecting this wire to the charge controller do I just stuff the raw stranded wire in the screw terminal? Seems dangerous. Tin the end? Or is there some kind of end crimp on end connector for this kind of application?

    Thanks!
    Rich
    12V 12W panel, SolarEpic Tracer4215BN, 12V 18Ah

  • #2
    I've been continuing my research and found this guy who does a bang up job of explaining how to size and purchase the right wire.
    https://www.youtube.com/watch?v=p1bnHu14SMs
    12V 12W panel, SolarEpic Tracer4215BN, 12V 18Ah

    Comment


    • #3
      Originally posted by Richiep View Post

      Are there any pitfalls for using oversized wire?

      Side question.
      When connecting this wire to the charge controller do I just stuff the raw stranded wire in the screw terminal? Seems dangerous. Tin the end? Or is there some kind of end crimp on end connector for this kind of application?

      Thanks!
      Rich
      Well, you've run into one pitfall... if the wire is thicker than the terminal can handle. I'm a fan of using ferrules to tame stranded wire (with a hexagonal crimping tool), but some types of terminals handle stranded better than others. If the terminal is only rated to accept smaller wire, it is proper to use a split bolt connector (or something like it) to transition from the heavier wire to something lighter than can be accepted by the terminal. Please don't just cut off strands to make it fit.

      Another related pitfall is that bigger wire takes more crimping force to terminate properly. 4 awg isn't too bad, but the bigger you go, the more difficult it will be to crimp properly.


      CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

      Comment


      • #4
        Originally posted by Richiep View Post
        I've been continuing my research and found this guy who does a bang up job of explaining how to size and purchase the right wire.
        https://www.youtube.com/watch?v=p1bnHu14SMs
        And he is totally (criminally) wrong about terminating the wires. Beware of youtube idiots

        Powerfab top of pole PV mount (2) | 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

        Comment


        • #5
          Probably the worst example if terminating cables out there. You could (literally) do a better job with a rock. I'm surprised this video has been allowed to remain on Youtube. At least the comments pretty much all, call this guy out on his bad advice.
          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

          Comment


          • #6
            Originally posted by Mike90250 View Post

            And he is totally (criminally) wrong about terminating the wires. Beware of youtube idiots
            I'm a noob over here so please point me in the right direction. I see they make a crimper that you bash with a hammer to install the crimp, $20

            Thanks!!!
            Last edited by Richiep; 09-28-2017, 09:03 AM.
            12V 12W panel, SolarEpic Tracer4215BN, 12V 18Ah

            Comment


            • #7
              Originally posted by Mike90250 View Post
              And he is totally (criminally) wrong about terminating the wires. Beware of youtube idiots
              Wow, that's pretty bad. Haven't seen the "put the terminal in a vise" thing in years.

              Comment


              • #8
                Originally posted by jflorey2 View Post
                Wow, that's pretty bad. Haven't seen the "put the terminal in a vise" thing in years.
                U-tube == The new idiot's bible.

                Comment


                • #9
                  To really, properly crimp cables larger then 6ga, you need a hydraulic crimper in the 6-15 ton range. The idea is not to simply deform the lug so it sticks to the wires, but to apply enough pressure with a 6 sided die, to fuse the copper strands to the tinplated copper shell and make it all gas tight. Can't do that with a "hammer/anvil" crimper.
                  You don't want a plain copper lug, tin plate is required for UL as it keeps the copper from oxidizing.
                  Soldering causes the solder to wick along the wire, making it stiff, and concentrates all bending forces at the end of the solder, usually causing a break in the cable in a couple months.
                  Solder can also melt and the connection falls apart in an overcurrent situation,
                  Powerfab top of pole PV mount (2) | 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

                  Comment


                  • #10
                    Originally posted by Richiep View Post

                    I'm a noob over here so please point me in the right direction. I see they make a crimper that you bash with a hammer to install the crimp, $20

                    Thanks!!!
                    bad connection especially on the thick wire (large current) is sure way to start fire, please listen to advice given here, $20 won't cut it.

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