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DC-DC Charge install Reflection 29RS

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  • #16
    Originally posted by Jkwilson View Post

    You are missing the entire key point. A battery is not a fixed load. Boosting the voltage at the battery INCREASES the current flowing into the battery. 100% absolutely and always. You can’t increase the voltage without increasing current, and you can’t increase the current without increasing the voltage.

    The voltage drop in the wiring causes the battery to draw less current. That means the battery is not getting all of the power that the tow vehicle charging circuit can provide. By boosting the voltage, the battery draws more current and receives more power, up to the ability of the charging circuit to provide power because the alternator sees a load it responds to.

    Numbers you might see with direct wiring to the trailer might be 13V and 6A providing 78W to the trailer battery. With the DC-DC converter you’d theoretically see 14.6V and 20A, though the circuit usually is current limited to more like 12A, providing ~175W to the battery.
    Thanks. But I'm not missing the entire point. I was not questioning on what is needed to charge a battery. I was questioning on why it appeared there was a belief the Renology part will put out 20A regardless of the capacity of the tow vehicle can provide to the input.

    I agree the Renology part is good (and pretty much necessary) as it performs two functions (especially in relation to LiPo RV batteries). It increase the Voltage as, yes, that is needed to actually put charge into the batteries AND it is intelligent in that it steps thru the 3 phases of battery charging and adjust the voltage according.

    My whole original response, and what I was still trying to explain, is that the Renology part does NOT and can NOT boost either power or specifically current "magically" when used with a tow vehicle that can only put out 6 amps. That is what I was (over?) reacting too.

    The OP latter responded with perhaps not a good choice of words.

    I just didn't want anyone thinking they could get 20A of charging out of the Renology device while the vehicle was limited (either due to Alternator output, wiring or fusing) to just 6 amps.

    Then the other people posting confused me more in some cases, so I continued to try and clarify (but I guess I failed)..

    I apologize, as hopefully we are all together now. Renology DC to DC Battery Charger is a good part of the solution. But it doesn't fix if your tow vehicle charging design is deficient. A user needs to understand if they want to provide 20A to their batteries from Renology part, then they need to provide (at least) 20A from their tow vehicle.

    Thanks,

    Comment


    • #17
      BLoflin

      I am pretty sure we are all on the same page, just each individual input and understanding is kind of hard to do in short posts, better discussed around a campfire. I will surely post some numbers once we get out of the winter funk and get to camping.

      Great discussion and input by all.

      Brian
      Brian & Michelle
      2018 Reflection 29RS Oct.2017 build date, EMS-HW50C , Lippert Remote
      2015 Chevy 3500HD CC LB Duramax , Reese Elite 18K
      630 ah battery, Victron Multiplus 2, 800 watts solar

      Comment


      • #18
        My Renogy was verified to deliver 20amps through my 7 way connector. It can draw up to 30amps depending on the TV output voltage so in the GM case (no promotion) when the tow haul mode is active or the headlights are on, the TV output voltage will be increased which helps to lower the overall load on the 7 way.

        Jim
        2017 Imagine 2600RB
        2015 GMC Sierra 4x4

        Comment


        • #19
          First question here on this DC-DC charger install. Thanks for the insight thus far.

          We have a 31MB Reflection, I upgraded the stock Progressive Dynamics power converter to the PD9100L (Lithium model). We have two 105Ah 12v lithium batteries in the RV. I am installing a Renogy 20v DC-DC battery charger. I used 4AWG from the truck batteries and opted to run that 4AWG line to a connection in the truck bed that will connect to a 4AWG run into the battery compartment and into the Renogy charger. I am not using the 7-way wiring.

          Thoughts on:

          Can I keep the PD9100L connected to the system via the current 7-way pin connection and will the converter's TCMS manage the PD9100L charging voltage output based on the volts the batteries are receiving from the tow vehicle/Renogy battery charger? Thus, with the TCMS, will the PD9100L adjust to not overload the battery because it senses the voltage of the battery at any given time/mode?

          Another instance- say, if the battery is 25% full (~12v) and I start charging it via the tow vehicle thru the Renogy battery charger and say I am getting a max of 14.1 v, will the PD9100 kick in and increase the volts to 14.6 (adding .5 volts) to that mode of the charging logic?

          Thanks
          Jason & Brittany
          2022 Reflection 31MB

          Comment


          • #20
            Originally posted by Wasatch View Post
            First question here on this DC-DC charger install. Thanks for the insight thus far.

            We have a 31MB Reflection, I upgraded the stock Progressive Dynamics power converter to the PD9100L (Lithium model). We have two 105Ah 12v lithium batteries in the RV. I am installing a Renogy 20v DC-DC battery charger. I used 4AWG from the truck batteries and opted to run that 4AWG line to a connection in the truck bed that will connect to a 4AWG run into the battery compartment and into the Renogy charger. I am not using the 7-way wiring.

            Thoughts on:

            Can I keep the PD9100L connected to the system via the current 7-way pin connection and will the converter's TCMS manage the PD9100L charging voltage output based on the volts the batteries are receiving from the tow vehicle/Renogy battery charger? Thus, with the TCMS, will the PD9100L adjust to not overload the battery because it senses the voltage of the battery at any given time/mode?

            Another instance- say, if the battery is 25% full (~12v) and I start charging it via the tow vehicle thru the Renogy battery charger and say I am getting a max of 14.1 v, will the PD9100 kick in and increase the volts to 14.6 (adding .5 volts) to that mode of the charging logic?

            Thanks
            Congrats on the project sounds like it'll be a good system. I assume you meant the 20A Renogy not the 20V.

            Keep in mind the converter does not affect the factory 7 way pigtail. That charge wire goes directly to the battery and has no charge profile built into it. Some people (myself included) run both the Renogy and 7 pin and some remove the 7 pin charge wire. howson recently had a write up on that process.

            Your converter will only do anything when you are connected to shore power or generator power.

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

            Comment


            • #21
              Thanks ncitro!

              Yes, 20A (oops)

              Appreciate the logic description of the converter only in the system during shore/generator power. I installed a PD 50A transfer switch to bring in an inverter and resolve the batter charging battery loop. The converter is on the shore power to ac panel side of the switch.

              From what I read, I believe the Renogy charger should read the battery charge level and even with the 7-way giving some juice, adjust the charge mode- is that what you are experiencing with your set up?
              Jason & Brittany
              2022 Reflection 31MB

              Comment


              • #22
                Wish people would stop saying the stock 7-pin can damage the lithium batteries, made it very confusing when I was spec'ing a system. That's simply not the case. It just won't charge them to 100% SOC.
                2022 Momentum 21G with factory 300w solar and generator
                2022 F-350 Lariat 6.7 PSD
                x2 206ah SOK LiFePO4 batteries

                Comment


                • #23
                  Originally posted by NickinCO View Post
                  Wish people would stop saying the stock 7-pin can damage the lithium batteries, made it very confusing when I was spec'ing a system. That's simply not the case. It just won't charge them to 100% SOC.
                  I haven't followed every post closely--who is stating using the 7-pin with the truck's OEM-provided charge will damage a lithium? Not my intent to "call someone out" but it is important, especially on this forum, to provide accurate technical information.
                  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


                  • #24
                    Originally posted by Wasatch View Post
                    Thanks ncitro!

                    Yes, 20A (oops)

                    Appreciate the logic description of the converter only in the system during shore/generator power. I installed a PD 50A transfer switch to bring in an inverter and resolve the batter charging battery loop. The converter is on the shore power to ac panel side of the switch.

                    From what I read, I believe the Renogy charger should read the battery charge level and even with the 7-way giving some juice, adjust the charge mode- is that what you are experiencing with your set up?
                    You will want to make sure that the converter is OFF when you are using the inverter, you do not want to take battery power to the inverter to the converter and charge the battery, the electrons will get confused and you will probably deplete your batteries.

                    Brian
                    Brian & Michelle
                    2018 Reflection 29RS Oct.2017 build date, EMS-HW50C , Lippert Remote
                    2015 Chevy 3500HD CC LB Duramax , Reese Elite 18K
                    630 ah battery, Victron Multiplus 2, 800 watts solar

                    Comment


                    • #25
                      Originally posted by Wasatch View Post
                      Thanks ncitro!

                      Yes, 20A (oops)

                      Appreciate the logic description of the converter only in the system during shore/generator power. I installed a PD 50A transfer switch to bring in an inverter and resolve the batter charging battery loop. The converter is on the shore power to ac panel side of the switch.

                      From what I read, I believe the Renogy charger should read the battery charge level and even with the 7-way giving some juice, adjust the charge mode- is that what you are experiencing with your set up?
                      Thats correct. In my case I still see the 7 amps or so from the seven pin contributing to charge until the batteries get towards full. More commonly I do not enable the DC to DC charger unless I know I will need it (towing in rain or clouds with a low SOC) no reason to stress the trucks alternators unless needed. In those cases I leave charging up to my solar panels and the stock 7 pin charger and again, I see the 7 pin contributing until they get towards full, then the solar panels top them off.


                      NickinCO ​​​Note that while I have not had any issues there have been concerns raised in the past about harm to the truck when using the stock wiring. In particular I know howson linked a article from AM solar stating the always disable the factory wiring when they do an install. I will see if I can find that discussion and link it.

                      Edit: Post 138 here:

                      https://gdrvowners.com/forum/operati...e-borns/page10
                      Neil Citro
                      2018 Reflection 28bh
                      2019 F350 6.7L Long Bed Crew Cab

                      Comment


                      • #26
                        Originally posted by ncitro View Post
                        ... linked a article from AM solar stating the always disable the factory wiring when they do an install. I will see if I can find that discussion and link it.
                        AMSolar's concern was for the truck's wiring not the lithium battery. What they said in that post was it 's possible for more current to travel on the 7-pin's return ("ground") wire than what it was rated to carry. That's why they will not install systems like what we've got in our trailers. At least that's what my gray matter remembers...

                        Since we're ... if I understand what Garret is saying, by disconnecting the power wire I have not mitigated the post's concern. Current associated with the battery charger could still find it's way back to the battery via the 7-pin's return path. I judge this risk (for me) to be negligible since there is a robust and direct return path to the battery to and from the charger in my configuration. But I'm just a shadetree backyard owner/technician so each person should weigh and evaluate this topic/risk for themselves.
                        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


                        • #27
                          howson That's right, hey I did remember the discussion lol. I also agree that risk is minimal and for the utility I get leaving it connected I'm okay with it. Obviously like a lot of things in the rigs everyone has to make their own decision.
                          Neil Citro
                          2018 Reflection 28bh
                          2019 F350 6.7L Long Bed Crew Cab

                          Comment


                          • #28
                            Originally posted by howson View Post

                            I haven't followed every post closely--who is stating using the 7-pin with the truck's OEM-provided charge will damage a lithium? Not my intent to "call someone out" but it is important, especially on this forum, to provide accurate technical information.
                            It is common on rv forums. Not specifically here. There is a youtube video of an unregulated alternator trying to charge a lithium battery...direct connection...guess what happens. They don't mention that truck electrical systems are regulated.
                            2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
                            2021 Reflection 303RLS, Haloview RD7, Strong-arms, Micro-Air364

                            Comment


                            • #29
                              Originally posted by Scott'n'Wendy View Post

                              It is common on rv forums. Not specifically here. There is a youtube video of an unregulated alternator trying to charge a lithium battery...direct connection...guess what happens. They don't mention that truck electrical systems are regulated.
                              This. Not technically here, just the net in general. I may disconnect the 7 pin power wire but I kind of like having it there for running the power jack, etc. Without it plugged in the power jack is pulling 11 amps. When my 7 pin is plugged in it pulls about 0.5a. Both SOK and Connected Current said I'm doing no harm by keeping it plugged in. It's been a while since I reached out to them but I believe battleborne said the same thing.
                              2022 Momentum 21G with factory 300w solar and generator
                              2022 F-350 Lariat 6.7 PSD
                              x2 206ah SOK LiFePO4 batteries

                              Comment


                              • #30
                                Originally posted by Scott'n'Wendy View Post

                                It is common on rv forums. Not specifically here. There is a youtube video of an unregulated alternator trying to charge a lithium battery...direct connection...guess what happens. They don't mention that truck electrical systems are regulated.
                                Scott,

                                Was it the Victron video? If so the alternator they used was regulated but it overheated from the lack of cooling due to low RPM. They moved to a balmar marine alternator with temperature control that pulled back on the charge when it began to overheat.

                                The point is to not let engines idle with high loads for prolonged periods while charging a lithium battery via the auto alternator. Auto manufacturers do not use temperature compensation and need RPM and vehicle movement to cool. The 7 way will not cause overheating at idle in its original configuration while connected to a lithium pack.

                                Jim
                                2017 Imagine 2600RB
                                2015 GMC Sierra 4x4

                                Comment

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