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  • As long as the normal resistance of the 7-pin charge circuit doesn't change there would be no reason for over-current.

    howson ,is there a reason for a second, redundant breaker in the 12 volt + line?
    Ted
    2021 Reflection 310RLS
    2020 F350 PS,CC,LB,SRW

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    • Originally posted by Jlawles2 View Post
      Yoda Keith, do we really want to know how many fuses you melted?

      Now Relays with a bad slide motor, I will say at least 4. Then after the dealer magically fixed it (they only replaced the relay which promptly went out the next time I ran the slide), I took the slide motor out, polished the burnt armature and it never missed a lick again.

      Dealers who run slides in and out on just the 7 way should be tied to a ground rod, soaked in salt water and forced to hold the hot line on an electric fence. The 7 way may run the cable type slides, but it's more likely to cause issues with the less than stellar brushed motors.
      Joseph - you would mention electric fences For another time

      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


      • Originally posted by TedS View Post
        As long as the normal resistance of the 7-pin charge circuit doesn't change there would be no reason for over-current.

        howson ,is there a reason for a second, redundant breaker in the 12 volt + line?
        Should the Renogy fail and allow power to backfeed (with the trailer disconnected from the truck) that second breaker will trip should there be an inadvertent short. I'll admit it's a highly unlikely scenario, but I didn't have any other experience or someone else's experience to fall back on with this config...so went super-conservative.
        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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        • Yoda I'll even play nice and let them use the solar ones.

          Charging batteries from the truck via a dc - dc charger, one needs to consider if they are creating the infinite loop of truck batteries powering the charger, and the coach batteries back charging the truck. I wonder if anyone has ever considered adding a large diode (or several) to prevent the back flow of power into he truck?

          https://www.etrailer.com/Accessories...RoCZ6oQAvD_BwE they are not very expensive and will prevent the coach from back feeding into the TV.
          Joseph
          Tow
          Vehicle: 2024 GMC K3500 Denali Ultimate Diesel
          Coach: 303RLS Delivered March 5, 2021
          South of Houston Texas

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          • Originally posted by Jlawles2 View Post
            Yoda I'll even play nice and let them use the solar ones.

            Charging batteries from the truck via a dc - dc charger, one needs to consider if they are creating the infinite loop of truck batteries powering the charger, and the coach batteries back charging the truck. I wonder if anyone has ever considered adding a large diode (or several) to prevent the back flow of power into he truck?

            https://www.etrailer.com/Accessories...RoCZ6oQAvD_BwE they are not very expensive and will prevent the coach from back feeding into the TV.
            Joseph
            I thought that back feed to the truck was already prevented in the charging circuit (at least by Ford), but maybe that's to the alternator. That will make for a good search tonight.

            Keith
            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.

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            • Originally posted by Yoda View Post

              WOW has this evolved - excellent discussion. After doing my own research I am convinced the its a CYA to disconnect the 7 pin charge line form the truck. When I do my 60A install I will not be disconnecting that line - it will be left alone Other than adding a power stud to one battery terminal I am not messing with the stock system. Besides it already fused at 30A at the truck regardless of the current direction......so how could there be an issue?

              SNIP
              Keith - without knowing the "smarts" incorporated by Ford into the circuitry which powers the 7 pin's + charge line I'd recommend disconnecting it. Your DC/DC charger is going to step up the voltage (a volt or two, perhaps) to properly charge a lithium battery (assuming that is the setting on the DC/DC). This voltage will be, at least at times, higher than the truck's voltage. Current will try to go backwards through the 7 pin's + wire, if the truck's circuitry and/or fusing will allow it. It's likely Ford has anticipated people inadvertently hooking up trailers with 24v batteries, etc., and has built in protection for this (on top of the 30a fuse), but I haven't proof of this. It seems like risk for no gain to not disconnect it.
              Ottertail, Minnesota
              2022 Imagine 2500RL VIN 573TE3029N6637046
              2022 Ford F-150 Lariat, SuperCrew, long box, max tow

              Comment


              • Originally posted by AlexPeterson View Post

                Keith - without knowing the "smarts" incorporated by Ford into the circuitry which powers the 7 pin's + charge line I'd recommend disconnecting it. Your DC/DC charger is going to step up the voltage (a volt or two, perhaps) to properly charge a lithium battery (assuming that is the setting on the DC/DC). This voltage will be, at least at times, higher than the truck's voltage. Current will try to go backwards through the 7 pin's + wire, if the truck's circuitry and/or fusing will allow it. It's likely Ford has anticipated people inadvertently hooking up trailers with 24v batteries, etc., and has built in protection for this (on top of the 30a fuse), but I haven't proof of this. It seems like risk for no gain to not disconnect it.
                Alex
                Very timely. I posted the question on one of the Ford Forums. So far I get the disconnect to Renogy being second rate. Right now I am good as I have 4-6V Crown 260 batterys in a bank delivering 12V (520 AH). So with his set up the charging profile matches the truck so no issue. Its when I switch to Lithium I am wondering. However I can't imagine Ford not having the reverse flow covered. Tomorrow I will be calling my dealer to ask the service manager if he knows anything. With the experts here I know we can solve this. Worst case I will install a diode on the 7 pin charge line as Joseph Jlawles2 suggest. I just need to know what size as the circuit is rated 30A ( I hope I have that right) and just hope I don't put it in backwards....which I have done in the past.....long long long ago in a city far away.........

                Thanks for the help
                Keith
                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


                • Originally posted by Yoda View Post

                  Alex
                  Very timely. I posted the question on one of the Ford Forums. So far I get the disconnect to Renogy being second rate. Right now I am good as I have 4-6V Crown 260 batterys in a bank delivering 12V (520 AH). So with his set up the charging profile matches the truck so no issue. Its when I switch to Lithium I am wondering. However I can't imagine Ford not having the reverse flow covered. Tomorrow I will be calling my dealer to ask the service manager if he knows anything. With the experts here I know we can solve this. Worst case I will install a diode on the 7 pin charge line as Joseph Jlawles2 suggest. I just need to know what size as the circuit is rated 30A ( I hope I have that right) and just hope I don't put it in backwards....which I have done in the past.....long long long ago in a city far away.........

                  Thanks for the help
                  Keith
                  Regarding the diode... they have a forward voltage drop of somewhere around .5 to 1.0v, so it almost renders the 7 pin's charge circuit ineffective anyway. I couldn't find the spec sheet for those diodes linked in this thread, so I don't know the exact fwd voltage drop.

                  I suspect blank looks from Ford's service techs...but, maybe they'll have diagrams of the internal circuitry that they will let you snap a picture of.
                  Ottertail, Minnesota
                  2022 Imagine 2500RL VIN 573TE3029N6637046
                  2022 Ford F-150 Lariat, SuperCrew, long box, max tow

                  Comment


                  • Testing the 7 pin circuit for one way should be pretty easy. Set the multi meter to diode test mode. Worst case you have to pull the fuse at the panel and test back to that point.

                    Keith, the diode I linked is pretty high amp rating at 85 amps. Much more than the wiring in the truck, but the fuse protects that, you just want to prevent battery back flow from the charger.
                    Joseph
                    Tow
                    Vehicle: 2024 GMC K3500 Denali Ultimate Diesel
                    Coach: 303RLS Delivered March 5, 2021
                    South of Houston Texas

                    Comment


                    • I just talked to my trusted Ford service manager. He pulled up the schematic that shows everything goes through the trailer control module, but there is no information on what inside it. He said he would try and reach out to Ford cooperate.

                      He then asked the voltage of the lithium which I said 14.7 or a bit more max charge rate. He then mentioned that should not be a problem as the alternator output under full load can go over 15V. He has seen 14.8 all day long. He is pretty confident it should not be an issue.

                      This was posted on the Ford thread - hope it helps

                      Click image for larger version

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                      Keith
                      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


                      • Originally posted by Jlawles2 View Post
                        Testing the 7 pin circuit for one way should be pretty easy. Set the multi meter to diode test mode. Worst case you have to pull the fuse at the panel and test back to that point.

                        Keith, the diode I linked is pretty high amp rating at 85 amps. Much more than the wiring in the truck, but the fuse protects that, you just want to prevent battery back flow from the charger.
                        Joseph - I believe one would have to either actuate the relay or jump it (yikes!) in order to test for whether or not there is a reverse polarity diode or other such thing in the circuit.

                        Yoda Thanks for the diagram - it appears that the relay is not used with the trailer tow module, whatever that is. One would surmise it goes with the various towing packages, but who knows? It seems the late model Fords will not connect the charge line without one application of the brakes after startup, maybe this module is involved somehow.
                        Ottertail, Minnesota
                        2022 Imagine 2500RL VIN 573TE3029N6637046
                        2022 Ford F-150 Lariat, SuperCrew, long box, max tow

                        Comment


                        • Originally posted by AlexPeterson View Post

                          Joseph - I believe one would have to either actuate the relay or jump it (yikes!) in order to test for whether or not there is a reverse polarity diode or other such thing in the circuit.

                          Yoda Thanks for the diagram - it appears that the relay is not used with the trailer tow module, whatever that is. One would surmise it goes with the various towing packages, but who knows? It seems the late model Fords will not connect the charge line without one application of the brakes after startup, maybe this module is involved somehow.
                          Alex
                          That is correct. It's my understanding that to activate the charge line is with the truck running, the door must be closed and the brake peddle pushed or the trailer brake controller manually activated. I am not sure it stays hot if the truck is put in park and door opened (truck running) . When the truck is turned off, the relay cuts the charge line to the trailer. I believes this prevents discharging the truck battery. If I get time today I might check a few things out with my multi-Meter.

                          I wonder if Rob Cate&Rob has verified any of this?

                          Keith
                          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


                          • Hi Keith, Joseph and Alex:

                            All that I have verified is that the truck charges the trailer battery when running and electrically disconnects from the trailer when the truck is turned off. I did not know about the sequence to activate the charge circuit . . . seems rather complex and unnecessary . . . but, wouldn't surprise me at all !

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

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                            • Originally posted by Cate&Rob View Post
                              Hi Keith, Joseph and Alex:

                              All that I have verified is that the truck charges the trailer battery when running and electrically disconnects from the trailer when the truck is turned off. I did not know about the sequence to activate the charge circuit . . . seems rather complex and unnecessary . . . but, wouldn't surprise me at all !

                              Rob
                              Oh, it's true. I found out after much frustration trying to figure out why there was no charge registering on the BMV. Closed the driver door--bingo. A whole whopping 9A.

                              Yoda (Keith) --respectfully--a lot of work for very little gain. With a DC-DC Charger the 7-pin's output is not relevant or needed. Are you sure the "juice is worth the squeeze"?
                              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


                              • Originally posted by howson View Post

                                Oh, it's true. I found out after much frustration trying to figure out why there was no charge registering on the BMV. Closed the driver door--bingo. A whole whopping 9A.

                                Yoda (Keith) --respectfully--a lot of work for very little gain. With a DC-DC Charger the 7-pin's output is not relevant or needed. Are you sure the "juice is worth the squeeze"?
                                Howard I have a bit of time to think about this and do more research (I find this subject interesting) as it only becomes a concern when I change over to Lithium in the future. So for now I am leaving things alone. As I mentioned worse case I will add a diode as Joseph Jlawles2 recommends if the voltage issue does present a real problem.

                                Are you changing your mind on disconnecting the 7 pin charge line?

                                Learning a lot
                                Keith

                                BTW Do folks have a recommendation on the size (type) and grade bolt to use on the positive battery terminal that does not have a factory aux stud. I was going to drill and tap a hole in the center of the dome embossed in the terminal and thread the new stud up from the bottom. I would then add a captive lock nut to the top so when making connections the new stud bolt does not move and maintains full connection.. I was thinking stainless as I believe the terminal is tin plated copper. I believe there would be a reaction with zink coated steel, I believe somewhere someone posted a good picture here, but I don't remember the details.
                                Thanks for any thoughts.

                                On edit. I talked to a Roadmaster tech and they say the 690 Single Park Light Diode will also work and has the same rating as the 790. Also he confirmed that putting this unit in line on the trailer charge circuit will solve any back feed issue. I did forget to get the power consumption number out of him though. https://www.roadmasterinc.com/produc...al/diodes.php#
                                Last edited by Yoda; 06-28-2022, 11:10 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.

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