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2/0 or 4/0 for 3000W inverter

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  • 2/0 or 4/0 for 3000W inverter

    I see many wiring diagrams (e.g. explorist.life) that show 4/0 cable to the inverter when upgrading from a 2000W inverter to a 3000W inverter. 2/0 I believe can handle up to 400amps. Is 4/0 really necessary? The reason I ask is I will be temporarily using a 2000W inverter that will not be wired in to the panel and 2000W and 2/0 is overkill even for that. But the long-term plan is to wire in a 3000W inverter to the panel. Even then, I don't see myself running the AC units on the battery. My BattleBorn GC3 270Ah battery is rated for 300amps. Just trying to figure out what would be drawing all these amps that would require 4/0 cable.
    2020 Reflection 303RLS

  • #2
    You can use 2/0 for a 3KW inverter if you distance from the battery(s) to the inverter is less than 5-6ft. Anything further than that and I would go to the 4/0 to avoid line loss.
    Jeff and Debbie
    2021 Imagine 2250RK
    2015 Ram 2500 6.7 CTD Crew Cab Short Bed Factory Air-Ride Auto Level
    USMC Veteran

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    • #3
      Most 3K inverters I have looked at call for 4/0 COPPER and 400 amp fuse. What do the instructions say to use. Also if you get 4/0 welding cable it is much easier ti use than std battery cable.
      Last edited by Yoda; 04-09-2021, 10:00 AM.
      2018 Reflection 150 Series 220RK 5th wheel. Reese R20 Titan hitch, Steadyfast system, 2004 F350 King Ranch dually

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      • #4
        I'd review the instructions that come with the inverter. Some inverters have surge capacity which requires larger wire sizes.

        Jim
        The moderators for this site are not GDRV employees, but we do own GDRV products.

        Jim and Ginnie
        2017 Reflection 297RSTS

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        • #5
          Thanks all. I decided to go with 4/0 cable.
          2020 Reflection 303RLS

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          • #6
            Originally posted by herman View Post
            Thanks all. I decided to go with 4/0 cable.
            I think that is a good choice. I did 4/0 between inverter and distribution and battery switch etc. I did 2/0 between individual batteries to distribution. Can find my thread here: https://gdrvowners.com/forum/operati...-and-questions

            I did it to where it is maybe a hair oversized. It may have worked with 2/0...but the larger cable will also give you more efficiency. Copper vs aluminum also matters. Here is a chart that may help you in the future:
            https://www.cerrowire.com/products/r...pacity-charts/
            2020 Imagine 2400BH
            2014 Ford F150 FX4 4x4 Supercrew 3.5 Ecoboost and tow package (not max tow)

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            • #7
              Originally posted by bellis View Post

              I think that is a good choice. I did 4/0 between inverter and distribution and battery switch etc. I did 2/0 between individual batteries to distribution. Can find my thread here: https://gdrvowners.com/forum/operati...-and-questions

              I did it to where it is maybe a hair oversized. It may have worked with 2/0...but the larger cable will also give you more efficiency. Copper vs aluminum also matters. Here is a chart that may help you in the future:
              https://www.cerrowire.com/products/r...pacity-charts/
              I could be wrong but I think when the batteries are wired in parallel you want the interconnecting wiring to be the same size as the largest feed leaving the bank. The idea being as I understand it is the power going out to the inverter in your case could be traveling on the 4/0 to the first battery and then on 2/0 to the next battery (it should be split, but wire sizing is worst case). If your 4/0 is overkill, you’re probably fine, but I think you normally want them the same.

              Neil Citro
              2018 Reflection 28bh
              2019 F350 6.7L Long Bed Crew Cab

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              • #8
                Originally posted by ncitro View Post

                I could be wrong but I think when the batteries are wired in parallel you want the interconnecting wiring to be the same size as the largest feed leaving the bank. The idea being as I understand it is the power going out to the inverter in your case could be traveling on the 4/0 to the first battery and then on 2/0 to the next battery (it should be split, but wire sizing is worst case). If your 4/0 is overkill, you’re probably fine, but I think you normally want them the same.
                That's not how Garret Towne configured my system, Neil. Interconnect between the batteries is 2/0 as the maximum sustainable amperage a Battle Born (BB) 100aH will output (or input) is 100 amps. 2/0 is more than sufficient especially with the very short lengths I'm using. Obviously if using batteries like bertschb's new 270aH BB battery (capable of 300amps output?), that would be a different story. Put a few of those together in parallel and you could light up a small city.

                The 4/0 from where the batteries come together to the inverter is because with four batteries and a 3000AH inverter the sustained amperage is 250. Surge can be up to 500! (The Battle Borns and Victron will do it--but only for about a second and then will say "No Mas!")
                Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

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                • #9
                  Originally posted by howson View Post

                  That's not how Garret Towne configured my system, Neil. Interconnect between the batteries is 2/0 as the maximum sustainable amperage a Battle Born (BB) 100aH will output (or input) is 100 amps. 2/0 is more than sufficient especially with the very short lengths I'm using. Obviously if using batteries like bertschb's new 270aH BB battery (capable of 300amps output?), that would be a different story. Put a few of those together in parallel and you could light up a small city.

                  The 4/0 from where the batteries come together to the inverter is because with four batteries and a 3000AH inverter the sustained amperage is 250. Surge can be up to 500! (The Battle Borns and Victron will do it--but only for about a second and then will say "No Mas!")
                  That’s true I forgot the battleborn batteries would limit the current so that would protect the wiring. I remember my Magnum inverter manual was very clear that the interconnecting wiring had to be the same size, but that wouldn’t take into account the BMS protecting.

                  Neil Citro
                  2018 Reflection 28bh
                  2019 F350 6.7L Long Bed Crew Cab

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                  • #10
                    I would guess depending on how the system is connected. If wired in parallel battery to battery, you would need to look at the sizing increasing toward the distribution point as amperage is added at each battery. If using a bus bar for the paralleling, then battery to bus bar needs to be capable of carrying what the battery can sustain, then the bus to device would need to be capable of the combined of all batteries or max amp draw of the device that is connected.
                    Tow Vehicle: 2018 GMC K2500 Denali Diesel
                    Coach: 303RLS Delivered March 5, 2021

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                    • #11
                      Originally posted by howson View Post

                      That's not how Garret Towne configured my system, Neil. Interconnect between the batteries is 2/0 as the maximum sustainable amperage a Battle Born (BB) 100aH will output (or input) is 100 amps. 2/0 is more than sufficient especially with the very short lengths I'm using. Obviously if using batteries like bertschb's new 270aH BB battery (capable of 300amps output?), that would be a different story. Put a few of those together in parallel and you could light up a small city.

                      The 4/0 from where the batteries come together to the inverter is because with four batteries and a 3000AH inverter the sustained amperage is 250. Surge can be up to 500! (The Battle Borns and Victron will do it--but only for about a second and then will say "No Mas!")
                      Howard - The maximum discharge for Battle Born batteries is 100 amps continuous, 200 amps for 30 seconds and higher loads for ½ second. The wiring should be sized for 200 amps if there is a possibility of a draw that high.

                      Jim
                      The moderators for this site are not GDRV employees, but we do own GDRV products.

                      Jim and Ginnie
                      2017 Reflection 297RSTS

                      Comment


                      • #12
                        Originally posted by TucsonJim View Post

                        Howard - The maximum discharge for Battle Born batteries is 100 amps continuous, 200 amps for 30 seconds and higher loads for ½ second. The wiring should be sized for 200 amps if there is a possibility of a draw that high.

                        Jim
                        That would mean I was pulling 800 amps from my four battery setup...if that was happening something's cooking. In the unlikely scenario the Multiplus pulls 500 amps for 1 second (or until the 400 amp fuse blows), the maximum draw from each of my four Battle Born batteries will be 125 amps (500/4). Based on charts I find online, this is under the max of ~175 amps the 2/0 can handle.

                        Given the 400 amp fuse protecting the circuit in my camper, that's the maximum amperage it should experience. Even if I "only" had three 100aH batteries (the minimum battery configuration suggested tied to a 3000W inverter) 2/0 would "work" since the maximum any single 2/0 (connected to a single battery) will experience (before the fuse blows) is about 133 amps. (400 / 3 = 133.33)

                        Heads are probably spinning right now with all the math--but again--the point is each configuration must be analyzed and configured as you noted for the maximum draw the circuit could experience before the safety device kicks in (aka "fuse").

                        One more example to drive home the point: an individual puts two 100aH batteries in parallel and connects to a 3000W inverter. The user inadvertently puts the inverter into an overload condition drawing 390 amps from the battery bank, which is just below the 400A fuse threshold. The Battle Borns and (Victron) inverter will do it--for a short time--thus the wires could experience 190 amps. That's just over (or right at) the 2/0 wire maximum specification. This configuration (number of batteries, wiring, and inverter) is not ideal.

                        Length of the wire used is a critical criteria, too. The same battery and inverter setup that is 12" apart will likely use a different wire from one that has the battery and inverter 50' from each other!

                        The point (and well made, Jim) is that each setup must be evaluated and wired based on it's configuration and capability. There's not a "one size fits all" answer. If my initial response gave that impression to the OP, I apologize...not my intent.

                        Howard
                        Last edited by howson; 04-10-2021, 12:31 PM.
                        Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                        Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

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                        • #13
                          I think you nailed the key point howson with "each setup must be evaluated and wired on its configuration and capability. Anyone working on electrical circuits should always design the protection method (fuse or breaker) to be the sacrificial failure point. Not the wiring or devices or under load.

                          Jim
                          The moderators for this site are not GDRV employees, but we do own GDRV products.

                          Jim and Ginnie
                          2017 Reflection 297RSTS

                          Comment


                          • #14
                            Really good points. Distance matters. Each configuration matters and maximum load. I would emphasize the shorter the wiring the better off you are with DC power. With AC power (and higher voltage) it's not as significant. Lower volts will always have more amps for the same wattage. Volts X Amps = Watts. More amps (or lower volts) mean bigger wires and shorter runs needed.
                            2020 Imagine 2400BH
                            2014 Ford F150 FX4 4x4 Supercrew 3.5 Ecoboost and tow package (not max tow)

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