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Switches, Breakers, and Fuses – Oh My!

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  • Switches, Breakers, and Fuses – Oh My!

    I’m making some modifications to our 2022 GD 280 RS fifth wheel and need some advice on the placement of switches, breakers, and fuses. This is my first venture into the world of low voltage systems, so please pardon my basic lack of understanding of the system. This group has been a great source of information, so I think that I have a workable plan, but need to make sure that I’ve interpreted the advice correctly.

    The first change is to replace the Furrion 50A MPPT controller with a Victron SmartSolar 100/30 controller in order to provide information and monitoring of the solar charge system. Adding another panel in the future is a possibility, but we first need to conduct some trials with what we have and the Furrion controller is just a black box. I definitely see the need for a disconnect switch between the 165W solar panel and the controller, but should there also be a fuse between the panel and controller? If so, how would I determine the size?

    Coming from the Victron controller and going to the OEM bus bar, I’m thinking that a 40A breaker should suffice.

    I’m replacing the 12V 80AH lead-acid battery with two 12V 200AH lithium batteries and adding a battery disconnect between the batteries and the OEM bus bar. Should there also be a fuse between the battery and the system or is that the purpose of the breaker box in the galley to which the converter is connected?

    As a side note, to complete the system I’m replacing the Furrion branded shunt with a Victron Smart Shunt 500A and adding Victron Smart Battery Sense units to provide battery temperature to the controller via Bluetooth and to me through the Victron app. All this gives me the ability to monitor the electrical system during the few days of boondocking we do each year.

    I’ve drawn diagrams of the existing and proposed wiring and have added pictures of the controller and the current state of the bus bar.
    Attached Files
    2022 Reflection 280 RS
    2020 Silverado 2500 HD

  • #2
    Fuse and breaker size is determined by the wire current rating, though it’s fine to go with a smaller protection device if the wire is oversized to eliminate voltage drop. You put the breaker or fuse close to the source of power, though this can become confusing in systems with multiple power sources. Usually batteries are the biggest concern, so breakers closer to them is better. Generally, very short wires or connecting jumpers protected in housings or non-flammable conduit may not need a circuit protection device.
    John & Kathy
    2014 Reflection 303RLS
    2014 F250 SC SB 6.2

    Comment


    • #3
      Originally posted by BR549 View Post
      ...should there also be a fuse between the panel and controller?
      IMHO, no. A solar array is a constrained power source. We know what it's maximum output will be in ideal conditions. (In contrast, a 12v RV battery is an unconstrained power source because the instantaneous output could be extremely, uncontrollably high.)

      If the wiring between the array and controller can handle the highest output of the array (with a safety factor) what's the purpose of the fuse? If the fuse is rated less than the maximum output of the panel there could be nuisance failures of the fuse. If the fuse is rated over the maximum output of the array, when will it blow?

      Originally posted by BR549 View Post
      Coming from the Victron controller and going to the OEM bus bar, I’m thinking that a 40A breaker should suffice.


      The maximum output of the Victron is 30 amps, so assuming the wiring is gauged sufficiently a 40A fuse (or breaker) sounds right. A quick look at https://footprinthero.com/fuse-size-calculator confirmed my guess.

      Originally posted by BR549 View Post
      I’m replacing the 12V 80AH lead-acid battery with two 12V 200AH lithium batteries and adding a battery disconnect between the batteries and the OEM bus bar. Should there also be a fuse between the battery and the system or is that the purpose of the breaker box in the galley to which the converter is connected?
      ​​​

      No additional fuse is required IMO. If you think of the battery as a gas tank, all you're doing is putting in a larger tank. The demand from the tank ("flow of gas") will still be the same, so the OEM connections will still suffice. Note that there are self-resetting circuit breakers near the battery (usually in the 30A range) that are the safety devices before the output of the battery reaches the Power Distribution Panel.

      Originally posted by BR549 View Post
      As a side note, to complete the system I’m replacing the Furrion branded shunt with a Victron Smart Shunt 500A and adding Victron Smart Battery Sense units to provide battery temperature to the controller via Bluetooth and to me through the Victron app. All this gives me the ability to monitor the electrical system during the few days of boondocking we do each year.
      ​​

      The SmartShunt has the ability to monitor battery temperature. Are you sure you need the Smart Battery Sense? https://www.victronenergy.com/batter...av-secondimage

      Click image for larger version

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      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.

      2017 Ford F-350 DRW, '19 315RLTSPlus

      Comment


      • #4

        The SmartShunt has the ability to monitor battery temperature. Are you sure you need the Smart Battery Sense?
        What I understand from the Smart Shunt manual is that you can add the BMV 712 or BMV 702 temperature sensor, but it's not clear if that will communicate with the SmartSolar controller. It would be great if it does, but the manual for the SmartSolar controller says that the controller will communicate with the Smart Battery Sense for temperature but it doesn't say that it will communicate with the Smart Shunt.
        Last edited by howson; 01-26-2023, 04:09 PM.
        2022 Reflection 280 RS
        2020 Silverado 2500 HD

        Comment


        • #5
          Originally posted by BR549 View Post
          What I understand from the Smart Shunt manual is that you can add the BMV 712 or BMV 702 temperature sensor, but it's not clear if that will communicate with the SmartSolar controller. It would be great if it does, but the manual for the SmartSolar controller says that the controller will communicate with the Smart Battery Sense for temperature but it doesn't say that it will communicate with the Smart Shunt.
          According to a Victron SmartSolar Charge Controller manual in my files:
          Optional external voltage and temperature sensor (range -20°C to 50°C) The Smart Battery Sense is a wireless battery voltage-and-temperature sensor for Victron MPPT Solar Chargers. The Solar Charger uses these measurements to optimize its charge parameters. The accuracy of the data it transmits will improve battery charging efficiency, and prolong battery life Alternatively, Bluetooth communication can be set up between a BMV-712 battery monitor with battery temperature sensor and the solar charge controller. For more detail please enter smart networking in the search box on our website.​


          The SmartShunt is the BMV-712 without the little screen. The SmartShunt manual even has a diagram with the VE.Smart Networking.

          Click image for larger version  Name:	Smartshunt ve network.jpg Views:	0 Size:	180.6 KB ID:	104282

          Howard
          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.

          2017 Ford F-350 DRW, '19 315RLTSPlus

          Comment


          • #6
            I just want to suggest a negative bus bar to go along with your set up. If you follow the white wires from the factory bus system to the foam underneath the bus system and remove a little bit of that foam you will find a wire nut with all of those white wires connected. Wire nuts are not the best solution for wire connections in a moving vehicle. I mounted a negative bus bar similar to this Amazon.com: Blue Sea Systems 2304 100 Amp Mini BusBar with 5 screws : Industrial & Scientific​ right beside that group of wires and bolted to the metal, this is where all of my grounds connect and then from there to the chassis. You can see this in the first picture in this thread Solar Install, Reflection 29RS Fifth Wheel - Grand Design Owners Forums (gdrvowners.com)​. You can also see that I just used a battery disconnect switch between panels and controller and breaker between controller and battery.

            Brian
            Brian & Michelle
            2018 Reflection 29RS
            2022 Chevy 3500HD

            Comment


            • #7
              Click image for larger version

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ID:	106103 howson Jkwilson Country Campers - before I disconnect something that I may need, I wanted to ask if you recognize what looks to be a relay. It has a red wire connected to the negative side of the bus bar; a black wire that goes to the grounding block with the white wire bundle; and a purple and a purple/white wire that goes into the foam sealant. It doesn’t appear to be part of the Furrion battery meter that I’m removing, but I don’t want to leave something that no longer functions.
              2022 Reflection 280 RS
              2020 Silverado 2500 HD

              Comment


              • #8
                BR549 I believe that is the relay for the 12V holding tank heaters.
                Ken & Sandra
                2021 303RLS | 2020 F350 Lariat 6.7L 4x4 SB SRW

                Comment


                • #9
                  That looks to be a standard 12V Relay. It can be wired NO or NC. It would be worth tracking down what activates this relay. Schematic is typically printed right on the relay.

                  Rob

                  Click image for larger version  Name:	133DC55C-799A-4B47-B2C4-208940E8FBE7.png Views:	0 Size:	302.8 KB ID:	106116
                  Cate & Rob
                  (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
                  2015 Reflection 303RLS
                  2022 F350 Diesel CC SB SRW Lariat
                  Bayham, Ontario, Canada

                  Comment


                  • #10
                    Originally posted by BR549 View Post
                    Click image for larger version  Name:	FD660188-9306-42AC-ADFF-ABF286F2E668.jpg Views:	0 Size:	125.4 KB ID:	106104 Click image for larger version  Name:	2CAAAA7F-6FDD-4E70-B87C-1CE697FF37D4.jpg Views:	0 Size:	102.1 KB ID:	106103 howson Jkwilson Country Campers - before I disconnect something that I may need, I wanted to ask if you recognize what looks to be a relay. It has a red wire connected to the negative side of the bus bar; a black wire that goes to the grounding block with the white wire bundle; and a purple and a purple/white wire that goes into the foam sealant. It doesn’t appear to be part of the Furrion battery meter that I’m removing, but I don’t want to leave something that no longer functions.
                    In case you wondering - in your first picture the 6 awg red wire attached to the circuit breaker (main one for trailer) goes down by the white wires. I am not sure why the second buss bar is there. That red wire is going to your disconnect switch. The 6awg black wire that comes back out of the same hole going to the far right that is connected to a second 6wag black wire is from the disconnect switch, The second 6 awg black wire is the positive feed to the 12v side of you distribution panel. I have no idea why GD changed wire colors at the disconnect switch, but in the 12V wiring in the trailer black is normally hot and white are the negative return wires sometimes called ground wires. On the AC side white is the neutral wires, Confused yet? If you don't have one I suggest getting a multi-meter to check.
                    Last edited by Yoda; 02-20-2023, 02:21 AM.
                    2018 Reflection 150 Series 220RK 5th whee, Star White 2022 F350 King Ranch CC Long bed (HAL) (CCC 4062lbs), B&W 25K OEM Companion,. SteadyFast system, Trailer reverse lights, rear receiver spare tire holder, storage tube, sumo springs, Victron MultiPlus 12/120/3000, Solar, Custom 6K axles upgrade, and other modifications.

                    Comment


                    • #11
                      Originally posted by BR549 View Post
                      Click image for larger version

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ID:	106103 howson Jkwilson Country Campers - before I disconnect something that I may need, I wanted to ask if you recognize what looks to be a relay. It has a red wire connected to the negative side of the bus bar; a black wire that goes to the grounding block with the white wire bundle; and a purple and a purple/white wire that goes into the foam sealant. It doesn’t appear to be part of the Furrion battery meter that I’m removing, but I don’t want to leave something that no longer functions.
                      KSC_Travels is correct. Found the image below on the Reflection Mini Auto Reset Breakers drawing GD provided to the moderators. Sorry I can't post the whole thing--not allowed.

                      Click image for larger version

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                      The relay allows a small switch to control the relatively high current of the heater pads. Once power is available, the pads are controlled by an internal thermostat (off at about 67F, on at about 42F).

                      Howard
                      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.

                      2017 Ford F-350 DRW, '19 315RLTSPlus

                      Comment


                      • #12
                        This is great information. As Yoda said it is indeed confusing, especially when you have zero electrical experience. I noticed the switch from red and black to black and white when I changed the converter. I assumed that trailer manufacturers use red/black near the batteries for that area to mimic automotive and black/white inside to mimic residential wiring. To me, it would be more logical to use red/black on all DC and black/white for AC power.

                        After I see how this project works out, and when I have more confidence, I’ll undertake moving the converter into the forward compartment with the batteries.

                        Thanks to all for your help and support.
                        2022 Reflection 280 RS
                        2020 Silverado 2500 HD

                        Comment


                        • #13
                          Originally posted by BR549 View Post
                          I assumed that trailer manufacturers use red/black near the batteries for that area to mimic automotive and black/white inside to mimic residential wiring. To me, it would be more logical to use red/black on all DC and black/white for AC power.
                          You have summed up the essence of wiring colour confusion in an RV! You are well on your way to making whatever mods you have in mind! Keep us updated.

                          Rob

                          Cate & Rob
                          (with Border Collies Molly & Angel + Kitties Hazel & Elsie)
                          2015 Reflection 303RLS
                          2022 F350 Diesel CC SB SRW Lariat
                          Bayham, Ontario, Canada

                          Comment


                          • #14
                            Is there a DC fuse between the forward compartment and the rest of the trailer? Everything is connected. The SmartShunt and SmartSolar check out and the DC light in the forward compartment works.

                            However, there is no current in the pass through or at the fuse box.
                            2022 Reflection 280 RS
                            2020 Silverado 2500 HD

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                            • #15
                              Oh yea. OEM disconnect. What a goof
                              2022 Reflection 280 RS
                              2020 Silverado 2500 HD

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