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  • 0 gauge wire question

    I have a 6000w inverter connected to four deep cycle batteries. if I use o gauge cable from inverter to batteries can I use 4 gauge cable to connect the batteries to each other or do I need o gauge for every connection?

  • #2
    No, I don't think so. What is the input voltage of the inverter?

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    • #3
      Originally posted by doorricade View Post
      I have a 6000w inverter connected to four deep cycle batteries. if I use o gauge cable from inverter to batteries can I use 4 gauge cable to connect the batteries to each other or do I need o gauge for every connection?
      You have to use the same size wire or larger ones for the battery interconnect. What is the battery bank's voltage? are you sure 0 gauge wire can supply 6000 watts DC current? 48 volts battery you need 125 amps and 24 volts you need 250 amps.

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      • #4
        Inter-Cell Jumpers must be as large as supply conductors. Stop and think about ir for a second. The Inter-Cell Jumpers pass just as much current as the Supply Conductors. Think of it like a chain. You do not use 1000-lb test chain and put a 100-lb link ink in it would you?
        MSEE, PE

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        • #5
          Originally posted by paulcheung View Post
          You have to use the same size wire or larger ones for the battery interconnect. What is the battery bank's voltage? are you sure 0 gauge wire can supply 6000 watts DC current? 48 volts battery you need 125 amps and 24 volts you need 250 amps.
          1/0 or 0 AWG is rated for 150-170A depending on temperature rating (70C vs 90C).
          It will betting getting hot at that current, so you need to make sure everything in the system is rated for those temps as well.

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          • #6
            Originally posted by emartin00 View Post
            1/0 or 0 AWG is rated for 150-170A depending on temperature rating (70C vs 90C).
            It will betting getting hot at that current, so you need to make sure everything in the system is rated for those temps as well.
            Most connectors/lugs etc are rated for 60C which means the wire also must be rated for the current at 60C
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            • #7
              Originally posted by Naptown View Post
              Most connectors/lugs etc are rated for 60C which means the wire also must be rated for the current at 60C
              Cheap lugs, yes. But if you buy high quality ones, they will be UL listed for 90C

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              • #8
                Originally posted by emartin00 View Post
                Cheap lugs, yes. But if you buy high quality ones, they will be UL listed for 90C
                Maybe there are some lugs that have a 90C rating but if you use circuit breakers their terminals have only a 75C rating.

                To be safe you should never use the 90C value to determine the current rating of wire.

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                • #9
                  Originally posted by emartin00 View Post
                  Cheap lugs, yes. But if you buy high quality ones, they will be UL listed for 90C
                  Yes but I know of no equipment made to operate at 90C. You only use 90C for current derating purposes of cables, but the Terminals of all equipment is rated 75C.
                  MSEE, PE

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                  • #10
                    Originally posted by Sunking View Post
                    Inter-Cell Jumpers must be as large as supply conductors. Stop and think about ir for a second. The Inter-Cell Jumpers pass just as much current as the Supply Conductors. Think of it like a chain. You do not use 1000-lb test chain and put a 100-lb link ink in it would you?
                    +1 with an additional condition:

                    If you are using 1/0 wire for the supply connection because the current being drawn requires 1/0, then the same current will be flowing through the inter-cell connectors unless you have parallel batteries or strings of batteries. That means that you would need to use 1/0 wire for the inter-cell connections too.

                    If, on the other hand, #4 wire is large enough to handle the current, and you are just using 1/0 for the long run to keep the voltage drop reasonable, then you could get away with using #4 between the cells. Just add up the length of all of the inter-cell connectors and decide whether that voltage drop is going to cause you problems too.

                    Now, let us look at the parallel battery situation:
                    You might think that if you will be drawing 200A from your bank which consists of two parallel strings of batteries that you can size the wire for only 100A.
                    There are at least two problems with that thought.
                    1. The current will not be perfectly balanced, so do not cut the wire size too close to that 100A capacity.
                    2. More important, what will happen if one battery string opens (fuse blows, cell goes open, wire connection breaks)? The other string will do its best to carry the full 200A. Result: melted wire.
                    So, even when using parallel battery strings, you cannot safely cut corners on the inter-cell wiring.

                    And even if the use of 1/0 is just for voltage drop, it makes sense to use the largest wire that you can bend (and get good terminations to fit) for the inter-cell connections.
                    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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                    • #11
                      o guage cable

                      Originally posted by doorricade View Post
                      I have a 6000w inverter connected to four deep cycle batteries. if I use o gauge cable from inverter to batteries can I use 4 gauge cable to connect the batteries to each other or do I need o gauge for every connection?
                      my inverter is 12v to 110v 6000w 12000w peak, batteries 12v 155ah agm deep cycle, 40 amp charge controller. renergy said 4 gauge is good enough for the batt. connections and to charge controller. i was told o gauge was better and what size fuse should i use and where would it be placed. thanks for the help.

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                      • #12
                        Originally posted by doorricade View Post
                        my inverter is 12v to 110v 6000w 12000w peak, batteries 12v 155ah agm deep cycle, 40 amp charge controller. renergy said 4 gauge is good enough for the batt. connections and to charge controller. i was told o gauge was better and what size fuse should i use and where would it be placed. thanks for the help.
                        Well that 6000watt 12v inverter can draw more than 500amps. That 1/0 wire can handle maybe 230amps which means it will melt when your load gets to 3000 watts.

                        So IMO I would install a fuse rated no more than 200amps at the battery on the wire going to the inverter.

                        Or I would replace that 6000w/12000w inverter with one that is around 600w/1200w peak. Then you might be ok using that #4 wire and a 100 amp fuse.

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                        • #13
                          Originally posted by inetdog View Post
                          If, on the other hand, #4 wire is large enough to handle the current, and you are just using 1/0 for the long run to keep the voltage drop reasonable, then you could get away with using #4 between the cells. Just add up the length of all of the inter-cell connectors and decide whether that voltage drop is going to cause you problems too.
                          Us train drivers and inspectors do not see it that way. Anytime you up size conductors to compensate for voltage loss, you must up size all current carrying conductors, including equipment grounding conductors, to handle the higher fault current available imposed on the system by lowering the overall system impedance......................................... .................................................. ............................................. So if Mr. Train Driver or Inspector passes by and catches it, we void your ticket and out the door you go. .................................................. .................................................. .................................................. .............. In a parallel situation makes us frown a bit because we have to do some math. If the Train Driver or Electrician did not put it in the Drawing Notes: but the sum of the cross-sectional area of the paralleled conducts must be equal to or greater than the single Feeder cable. Better hope it is right because Mr. Inspector is not happy having to use a calculator and take the time someone else should have done for him already. :P
                          MSEE, PE

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