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  • Looking for critique of my solar plans for 22MLE

    Hello all,

    I have already gotten some input from Howard in a previous thread concerning the connections between the solar panels and the charge controller, but now I am posting my "full" plan/schematic and would appreciate some of the more knowledgeable solar veterans to give it a once-over.

    On a previous trailer I installed 1 panel with a PWM controller and went straight to the lead-acid battery on the trailer tongue and did not alter any of the existing wiring. But this time I am going a little more in depth and will be making alterations to factory wiring too.

    We do not need a "full blown" setup like some of you full time boon-dockers have, but rather just enough to get us through a 3 day boon-docking trip. So we really have no need for much in the way of AC power, as we aren't looking to run the microwave or anything like that. I just want to have all the normal 12v DC functions of trailer working and possibly running the furnace at nights. If anything, I might add a small 800 watt inverter down the road if it ends up that we have power to spare. But right now I just want to get the DC part of the puzzle all worked out and done correctly.

    Yesterday I took out a few of the bolts and pulled down the underbelly chloroplast just far enough to see in there with a flashlight. I "think" I can see how the factory wiring is done, and how it feeds to the disconnect switch in the pass-thru. But I am still not 100% sure, and probably won't know until this Spring when I can fully drop the underbelly and have a good look. So it might end up being that some of my wiring plans back to the WFCO will need to be altered if I find things aren't run the way I think they are right now.

    Any and all suggestions and fault finding is most appreciated. You will not hurt my feelings
    And I apologize in advance for my lack of schematic drawing skills. Hopefully it is not too jumbled and confusing.

    Thanks,
    Billm321

    Click image for larger version

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    Last edited by BillM321; 02-21-2021, 07:20 PM.
    Bill M.
    2021 Imagine XLS 22MLE
    2021 F-150 3.5L EcoBoost

  • #2
    A couple of things I see, Bill.

    The OEM configuration has the emergency brake on a self-resetting circuit breaker. That breaker's being replaced with a fuse?

    The WFCO 8735P can output 35 amps while charging the Battle Born. That's .35C, or 35aH, which is a good rate since Battle Born recommends .5C (50 amps) or less. If you install a second (or more) battery(ies), a higher capacity charger and wires > 8ga between the charger and battery bank should be considered. Why? Because two Battle Born batteries charging at .5C can consumer 100aH if the charger can provide it. The time saved when hooked up to shore power may be worth it.

    Finally, solar is an unreliable resource to know your battery will be recharged the next day when at a location without shore power. A small inverter generator might be a consideration for an emergency charge source. (Lots of threads recently on that topic.)

    Keep in mind that even a "small" 800W inverter can sustain about 6 amps of 120vAC which means the inverter is drawing 60 amps of 12vDC from the battery. In less than an 1/2 hour about 50% of the Battle Born will be depleted at that rate.

    I'm sure others will chime in here soon, like Guest , ncitro and TucsonJim among others...
    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

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    • #3
      Originally posted by howson View Post

      The OEM configuration has the emergency brake on a self-resetting circuit breaker. That breaker's being replaced with a fuse?
      Thank you sir !

      In regards to the emergency break-away.....I am not sure I understand your question.

      I think the way it is wired now is that it is on the same post of the circuit breaker as the battery is (wires 2 and 3 are the Jack and emergency break-away, and wire 4 is the battery). So there is no breaker "in-between" the battery and the emergency break-away right now. I may be wrong, but I don't think there are any in-line fuses on either battery (wire4) or the break away (wire3). The electric jack certainly has an in-line fuse. I will have to take a look again next time I get a warm day.

      Click image for larger version

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      Billm321
      Attached Files
      Bill M.
      2021 Imagine XLS 22MLE
      2021 F-150 3.5L EcoBoost

      Comment


      • #4
        What Howard is pointing out.....with the original battery feed removed and the switch installed on the battle born battery, your battery switch much be in the on position to power the break away switch. This switch in its OEM configuration is wired directly (bat side of breaker) to the battery and is not fused. Your configuration is similar to mine where based on your diagram, you are back feeding the dotted purple circuit.

        Two ways to handle this.

        1) Be certain your battery switch is on for travel and cannot be inadvertently shut off.
        2) Install a dedicated break away unit with integrated battery and charger.

        Jim

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        • #5
          BillM321

          Jim is even more conservative on the issue of emergency brake power than I am. He (rightfully) points out the OEM configuration has it wired prior to the cutoff so it is always powered if the battery has power.

          I was wrong (and Jim right) about where the brake system is wired--sorry 'bout that. He's also right that the system wasn't protected. That's been a subject for debate on this forum in the past.

          When my brakes were converted to disc by MorRyde, they installed a 40A self-resetting breaker between the HydraStar hydraulic brake fluid pump and battery bank but still left the switch (that signals the pump to fire) unprotected. Some may see the 400A fuse before that wire, but the 400A fuse is not going to blow before the wire melts.

          If a system is protected what I've seen in my (very) limited experience is a self-resetting breaker, not a fuse. Just something to consider and maybe this will generate more info on "why" for those with more experience on this topic.

          For reference, here's diagrams I found in my files of my 12v system. Original config from GD on the left, how it is currently wired on the right.

          Click image for larger version  Name:	12v DC Wiring Diagram v4 with OEM for comparison.jpg Views:	0 Size:	161.0 KB ID:	43598

          There's a PDF version attached so you can zoom in easily on any area of interest.

          Howard
          Attached Files
          Last edited by howson; 02-22-2021, 09:01 AM.
          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

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          • #6
            I looked into this a while ago and figured a good way to do this while keeping to the unprotected connection is to add on a dedicated break away kit. This kit contains an on board battery and charger where the feed wire can be protected from inside the rig, or simply connected to the original battery cable location and with the battery switch turned on for charging. Some do not feel comfortable with an unprotected wire being fed from inside the rig and directly connected to the break away switch. Other feedback I've received on this was an auto re-set breaker can be used for the break away switch but must be dedicated only to the switch and no other components. Some will back-feed as you are planning and just keep the battery switch on and not be concerned. One caution on the OEM switch though....is that it will eventually wear out the cam and will shut off while traveling. I ran across this when my Furrion camera kept failing intermittently while on the road.
            A quality replacement switch to directly replace the OEM switch is made by Sierra and can be purchased from West Marine.

            https://www.curtmfg.com/towing-elect...y-systems/kits

            https://www.westmarine.com/buy/sierr...58?recordNum=1

            Jim

            Comment


            • #7
              Count me in the "make sure the switch is on" camp. I have my shutoff wired to kill everything. That said I removed the factory shutoff (it kept getting bumped in the pass through) and have my main shutoff in the front bay with the rest of my 12V gear. I also have the landing gear going through the shutoff, so it is pretty much impossible to hook up without turning on power, so by extension I should never pull away with no power to the brakes.
              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.

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

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              • #8
                OK...you all have convinced me to have constant power to the emergency break-away with no chance of a switch forgetting to be turned on. And since I am not really looking for AC power on short boon-docking trips, I have decided to ditch the small inverter. So I think all I am going to do is re-use the existing trailer wiring for the most part. I will move the new LiFePO battery into the pass-thru area and then run some new 6AWG wires from the new battery to exactly the same points the OEM battery was wired to. The trailer won't know the battery is in the pass-thru versus out on the tongue.

                So here is "take 2" on my solar plans. This should be cheaper and easier to install. I think I can do without any bus bars too. I am still not 100% sure how the factory installed battery cut-off switch is wired, so that part of the wiring schematic may have to be revised once I get a chance to pull down the chloroplast and really delve into this when the weather warms up.

                Let me know what you think of this simplified design.

                I do have 2 questions though:

                1. Concerning the 30amp resetting breaker on the trailer tongue. Those things are bi-directional aren't they? I see in other schematics that is says gold terminal is power and silver terminal is load side. But they allow current in both directions don't they? How else would the +12v of the trailer/truck wiring ever trickle charge the battery if current couldn't flow from the "load side" to the "input side" ? Am I not understanding something here?

                2. Is a 50amp terminal fuse to much? Should I use a 30amp terminal fuse?

                Click image for larger version

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                Last edited by BillM321; 02-23-2021, 12:35 AM.
                Bill M.
                2021 Imagine XLS 22MLE
                2021 F-150 3.5L EcoBoost

                Comment


                • #9
                  Bill,

                  The copper post on the breaker is the battery feed side. For 6AWG I would calculate the max load and use an Ampacity chart to determine the size of the breaker and wire. I use 4AWG from my battery to a 60amp charger where the recommended breaker size is 80amp.

                  https://www.bluesea.com/resources/1437

                  Jim

                  Comment


                  • #10
                    I'm in the same boat as BillM321, I jus purchased (3) 210W 12v Panels from NewPowa, will be connected to my 50A MTTP.
                    The standard cabling is 10 AWG (30A) in a "Solar Prep" RV. Do I have a problem here?
                    Is my cabling under sized? Also Do I need a breaker or fuse between the panels and the MPPT? What size?
                    Do I need a breaker or fuse between the MPPT and the (2) 206Ah SOK lithium batteries? What size? Please advise.

                    Comment


                    • #11
                      Originally posted by TheGoletaLemon View Post
                      I'm in the same boat as BillM321, I jus purchased (3) 210W 12v Panels from NewPowa, will be connected to my 50A MTTP.
                      The standard cabling is 10 AWG (30A) in a "Solar Prep" RV. Do I have a problem here?
                      Is my cabling under sized? Also Do I need a breaker or fuse between the panels and the MPPT? What size?
                      Do I need a breaker or fuse between the MPPT and the (2) 206Ah SOK lithium batteries? What size? Please advise.
                      Assuming you are wiring all three panels in parallel, that could be a little over 52 amps. I think that would be over the limit for 10 AWG wire. You should consider larger wire or maybe putting them in series if your controller can handle it.

                      For fusing, check the manual for your controller. On my Victron controller, I used a disconnect on one side and a breaker on the other (switch on the panel side, breaker between the controller and the batteries). The size of the breaker would need to match the size of the wire you run from the controller to the batteries (the breaker protects the wiring).

                      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.

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

                      Comment


                      • #12
                        Originally posted by TheGoletaLemon View Post
                        I'm in the same boat as BillM321, I jus purchased (3) 210W 12v Panels from NewPowa, will be connected to my 50A MTTP.
                        The standard cabling is 10 AWG (30A) in a "Solar Prep" RV. Do I have a problem here?
                        Is my cabling under sized? Also Do I need a breaker or fuse between the panels and the MPPT? What size?
                        Do I need a breaker or fuse between the MPPT and the (2) 206Ah SOK lithium batteries? What size? Please advise.
                        Your questions are exactly why I consistently recommend folks buy Will Prowse's book Mobile Solar Power Made Easy. I did. For $15 it's well worth it. I spent many nights reading it and watching Will's YouTube videos. I also watched AMSolar's videos (the MPPT controller one is excellent).

                        Unfortunately there's no shortcut if you want to do it yourself, understand the capabilities of your system, it's configuration, and what to do when something goes wrong. Knowing why leads to what.

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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

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                        • #13
                          howson, Thank you I will check it out.

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