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  1. #11
    Setting Up Camp
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    Quote Originally Posted by SolarPoweredRV View Post
    Chad,

    Here are a couple of threads that discuss switching to Lithium and adding an Inverter in great detail:

    Affordable-Solar-How-To-Design-and-Install-an-Affordable-Solar-System

    Installing-a-Solar-System-in-Phases
    Thanks for the input, your thread on installing in phases is great info.
    2018 Momentum 397TH
    2021 Ford F350 DRW

  2. #12
    Seasoned Camper
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    Quote Originally Posted by Chad74 View Post
    Yea solar is another topic and probably wont be done on this trailer.
    I'm at the very beginning stage of this possible project and haven't compared prices but if I can get 2-200AH for the same or close to 4 100AH then I will go that route. But now I'm just getting an idea of what is needed.
    A couple of things to consider...
    If your ultimate goal is to someday run the entire RV from an inverter, sometimes more batteries is better. Most LiFePo4 batteries limit the output to 100 amps continuous. Two, 200ah batteries may only get you an output of 200 amps - not enough to properly power a 3k inverter. The four 100ah batteries connected in parallel will get you an output of 400 amps.

    In my location, solar is not necessarily a great option. Most of our summers are overcast (May gray and June gloom). When I started down this rabbit hole, I tried to imagine the ultimate end game given the conditions I have to deal with. I ended up going with a 60 amp DC-DC Charger and 3k inverter. I currently have a single 200ah LiFePo4 so my inverter is limited to about 1k at this point - larger battery bank to come later.

    I guess my point is, plan ahead and overbuild everything. As you have already seen, there are some great resources here.
    2022 Ram 2500 4x4, 6.7 Cummins, RamBox, Air Lift 5000 Ultimate Plus, B&W Companion
    2022 Reflection 303RLS, Progressive hardwired EMS, Airborne Sidewinder
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  3. #13
    Fireside Member
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    Quote Originally Posted by Chad74 View Post
    2018 Momentum 397th, no solar
    Current lead acid battery is the original, so I know it is on borrowed time. So I am thinking about going lithium.
    I have read that some people don't change their charging system but that isn't utilizing the batteries to their full abilities.
    My question is kind of a two part question.
    1. What exactly is needed to convert to lithium?
    2. What is needed to run TV off the batteries if not hooked to shore power? I don't want to run generator just for the tv.

    TIA
    Chad
    You can go cheap for now as I have to run tv. Bought 2 AGM batteries and a 500watt portable pure sine inverter to watch tv and charge phones when boondocking. This gives me a few years to design my lithium project with 2000watt inverter to run all outlets and microwave in my Momentum 21g. Good luck
    2022 Momentum 21G
    300ah LiFePo4, 525 watt solar
    2015 Ram 1500 5.7 Hemi

  4. #14
    Left The Driveway
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    I added a small automotive inverter the car lighter type I think it is rated at 125w, it is zipped tied to the TV mount. Added lighter plug at the stereo 12v power, the Roku tv only used about 50watts. Have a apple to too. Works for now. I’ll upgrade later.

    I went lithium batteries as well, changed out the converter charger, biggest pain is I had to install larger 12v (2gauge) wire since my charge/converter is in the main cabin on our imagine 2400BH.

    Not the best pic
    Click image for larger version. 

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  5. #15
    Setting Up Camp
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    Quote Originally Posted by Toy Haulen View Post
    You can go cheap for now as I have to run tv. Bought 2 AGM batteries and a 500watt portable pure sine inverter to watch tv and charge phones when boondocking. This gives me a few years to design my lithium project with 2000watt inverter to run all outlets and microwave in my Momentum 21g. Good luck
    How did you integrate that into the existing system?
    2018 Momentum 397TH
    2021 Ford F350 DRW

  6. #16
    Site Sponsor SolarPoweredRV's Avatar
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    Quote Originally Posted by Jomani View Post
    A couple of things to consider...
    If your ultimate goal is to someday run the entire RV from an inverter, sometimes more batteries is better. Most LiFePo4 batteries limit the output to 100 amps continuous. Two, 200ah batteries may only get you an output of 200 amps - not enough to properly power a 3k inverter. The four 100ah batteries connected in parallel will get you an output of 400 amps.

    In my location, solar is not necessarily a great option. Most of our summers are overcast (May gray and June gloom). When I started down this rabbit hole, I tried to imagine the ultimate end game given the conditions I have to deal with. I ended up going with a 60 amp DC-DC Charger and 3k inverter. I currently have a single 200ah LiFePo4 so my inverter is limited to about 1k at this point - larger battery bank to come later.

    I guess my point is, plan ahead and overbuild everything. As you have already seen, there are some great resources here.
    It is important to understand that when you parallel Lithium batteries, the output might be limited by the internal BMS (Battery Management System), i.e.: stringing 4, 100 amp (current draw, not amp hour rating), batteries may be limited to only 100 amps of current draw because, all the power is going through a single battery that is attached to the load and the BMS is limiting the amount of power that can be drawn to 100 amps (you would still get 400amp hours of energy storage, only be limited to drawing 100 amps).

    The way to get around this limitation is to use Buss Bars. Attach each cable from the battery to the Buss Bars (one positive and one negative) and then attach the load to the Buss Bar. This way, each battery can contribute their entire 100 amps to the load instead of being limited by the Internal BMS of the first battery.

    Here is an example of the type of Buss Bar I am talking about. Additionally, I have attached a research paper that explains the advantage of using Buss Bars in detail (I also included a Wire Gauge Chart):
    Attached Thumbnails Attached Thumbnails 81yMvCyIUXL._AC_SL1500_.jpg   Parallel Battery Wiring.pdf   Color Wire Size Chart.jpg  
    David and Peggy
    2019 Ford F350 Lariat, 6.7L Diesel, Dually, Long Bed
    Running with 20k Reese Goosebox (Love It) and Ford Factory "Puck" system.
    Stopping with 8,000 lb Disc Brakes and Titan Hydraulic over Electric Brakes system.
    Powering all this fun with 1200 Watts of Solar, two Tesla, Model S, battery modules, 24 volt Victron Inverter.
    2018 Solitude 310 GK

  7. #17
    Fireside Member
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    Quote Originally Posted by Chad74 View Post
    How did you integrate that into the existing system?
    I added an SAE plug under control panel wired to the 12 volt buses. Then I can plug my] inverter directly into SAE plug.
    Click image for larger version. 

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    Attached Thumbnails Attached Thumbnails 20220819_112003.jpg  
    2022 Momentum 21G
    300ah LiFePo4, 525 watt solar
    2015 Ram 1500 5.7 Hemi

  8. #18
    Seasoned Camper
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    Quote Originally Posted by SolarPoweredRV View Post
    It is important to understand that when you parallel Lithium batteries, the output might be limited by the internal BMS (Battery Management System), i.e.: stringing 4, 100 amp (current draw, not amp hour rating), batteries may be limited to only 100 amps of current draw because, all the power is going through a single battery that is attached to the load and the BMS is limiting the amount of power that can be drawn to 100 amps (you would still get 400amp hours of energy storage, only be limited to drawing 100 amps).

    The way to get around this limitation is to use Buss Bars. Attach each cable from the battery to the Buss Bars (one positive and one negative) and then attach the load to the Buss Bar. This way, each battery can contribute their entire 100 amps to the load instead of being limited by the Internal BMS of the first battery.
    Each individual BMS controls the output of it’s specific battery. When connected in parallel (connecting all positive together and all negative together), the external cabling creates a version of the bus bar you are talking about. Each battery will output the max allowed by the BMS. Series and series/parallel circuits will certainly produce the the effect you describe.

    When passing high current such as feeding an inverter, an external bus bar can certainly improve battery efficiency and help to eliminate the problems outlined in the article. Best case would be to use identical cable lengths from each battery. Doing so would help to create identical voltage drops across each cable and, in theory, pull the same load from each battery.
    2022 Ram 2500 4x4, 6.7 Cummins, RamBox, Air Lift 5000 Ultimate Plus, B&W Companion
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  9. #19
    Site Sponsor SolarPoweredRV's Avatar
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    Quote Originally Posted by Jomani View Post
    Each individual BMS controls the output of it’s specific battery. When connected in parallel (connecting all positive together and all negative together), the external cabling creates a version of the bus bar you are talking about. Each battery will output the max allowed by the BMS. Series and series/parallel circuits will certainly produce the the effect you describe.

    When passing high current such as feeding an inverter, an external bus bar can certainly improve battery efficiency and help to eliminate the problems outlined in the article. Best case would be to use identical cable lengths from each battery. Doing so would help to create identical voltage drops across each cable and, in theory, pull the same load from each battery.
    You need to read the research paper shown above. The authors state "If we draw100 amps from the first battery (In the configuration you describe) we will effectively be drawing 25 amps from each battery. OR SO WE THINK.

    In actual fact what we find is that more current is drawn from the first battery (the battery attached to the load) with the current getting less and less the further we get from the first (load) battery".

    This is why the BMS in the first battery can, in fact, limit the power output (amperage) of the entire string.
    David and Peggy
    2019 Ford F350 Lariat, 6.7L Diesel, Dually, Long Bed
    Running with 20k Reese Goosebox (Love It) and Ford Factory "Puck" system.
    Stopping with 8,000 lb Disc Brakes and Titan Hydraulic over Electric Brakes system.
    Powering all this fun with 1200 Watts of Solar, two Tesla, Model S, battery modules, 24 volt Victron Inverter.
    2018 Solitude 310 GK

  10. #20
    Seasoned Camper
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    Quote Originally Posted by SolarPoweredRV View Post
    You need to read the research paper shown above. The authors state "If we draw100 amps from the first battery (In the configuration you describe) we will effectively be drawing 25 amps from each battery. OR SO WE THINK.

    In actual fact what we find is that more current is drawn from the first battery (the battery attached to the load) with the current getting less and less the further we get from the first (load) battery".

    This is why the BMS in the first battery can, in fact, limit the power output (amperage) of the entire string.
    I agree - at least until we get to the last sentence. If the load is connected to the first or last battery in the string, that battery will have a tendency to discharge at a higher rate up to the point where the BMS starts to limit the current. At that point, the remaining batteries will ramp up output to meet the demand. When charging, the inverse will happen.

    I think the point of the article is that every attempt should be made to balance the load by matching circuit resistance. As you point out, a bus bar is a good way to do this.
    2022 Ram 2500 4x4, 6.7 Cummins, RamBox, Air Lift 5000 Ultimate Plus, B&W Companion
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