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  1. #1
    Rolling Along
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    Lithium and charger

    I have tried in the past but the answers tend to be confusing to me and it may have been how I asked it so I am going to go into detail.

    I have a 231RK and it has the WFCO 9855 converter in it (not AD). I have a lead acid battery in the TT and all is happy.

    I was thinking of doing a LiFePO4 battery. I know if I just throw it in, the charger will not fully charge the battery. The solar could because I can switch it.

    So, here is the question in detail. If I just install the LiFePO4 battery, hook it up to the TT as is, can I just go purchase a Victron Smart IP22 12-Volt 30 amp charger and connect that to the battery?

    I am just wondering and don't need the, "just swap everything out" answer. This is actually one of my, "I wonder...." questions.
    Upstate NY
    2022 Ford F150 with trailer tow package
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  2. #2
    Site Team Redapple63's Avatar
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    Quick answer is yes this will do a good job charging your lithium’s. The 9855 is a deck mount converter charger so not sure what you would do for a converter (12v). Maybe you could just rely on the batts for 12v even when on shore power. I think this would work.

    Bill
    2019 GMC 3500 SRW Sierra Denali Duramax
    2020 Reflection 315RLTS

  3. #3
    Seasoned Camper
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    Quote Originally Posted by Redapple63 View Post
    Quick answer is yes this will do a good job charging your lithium’s. The 9855 is a deck mount converter charger so not sure what you would do for a converter (12v). Maybe you could just rely on the batts for 12v even when on shore power. I think this would work.

    Bill
    I agree. There is a common misperception that running more than one charge controller will cause them to fight between each other, especially when they will often be operating in different modes.

    Each charge controller will attempt to measure the internal resistance of the battery (or more accurately the entire circuit). The lower the resistance, the more discharged the battery. As the internal resistance increases, each charge controller will independently change to different modes of operation - in this case that will happen at different times because they have different charging algorithms. Because it is a LiFePo4 battery, the stock charge controller will enter float mode long before the lithium compatible charge controllers. Your solar charge controller should also continue to charge after the stock charge controller has entered float mode.

    Depending on cable length and size (remember they measure circuit resistance) each charge controller may read the internal resistance of the battery differently. Will Prowse does a very good job of explaining it in this video.
    https://youtu.be/rSj6-JSxoD4
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  4. #4
    Rolling Along
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    Quote Originally Posted by Redapple63 View Post
    Quick answer is yes this will do a good job charging your lithium’s. The 9855 is a deck mount converter charger so not sure what you would do for a converter (12v). Maybe you could just rely on the batts for 12v even when on shore power. I think this would work.

    Bill
    Thanks for the information. I was wondering how it would work because in theory you would have three chargers. Although, adding the specific LifePO4 charger would be about the same cost as replacing the Stock converter.

    I am still working the math out in my head. In theory, I could get a 100% charge on the battery with the Stock converter and the solar panels set to lithium. From what I read the solar set up should charge a 100AH LifePO4 (from 0%) in about ten hours. Since there is no drain on the battery when plugged into shore power I would assume the battery could get to 100%.

    This is a tough subject in my opinion because most would just swap out everything.
    Upstate NY
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  5. #5
    Site Team Ynot4me2's Avatar
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    Quote Originally Posted by docque View Post
    Thanks for the information. I was wondering how it would work because in theory you would have three chargers. Although, adding the specific LifePO4 charger would be about the same cost as replacing the Stock converter.

    I am still working the math out in my head. In theory, I could get a 100% charge on the battery with the Stock converter and the solar panels set to lithium. From what I read the solar set up should charge a 100AH LifePO4 (from 0%) in about ten hours. Since there is no drain on the battery when plugged into shore power I would assume the battery could get to 100%.

    This is a tough subject in my opinion because most would just swap out everything.
    This is correct. You can add a separate charger.
    I'm currently building my own DIY Lithium battery and plan to only use it as a drop in replacement for the first season or 2. Since my current converter/charger is the all in one and not lithium compatible, I'll be bringing my lithium charger (120v 10amp) NOCO charger along. I plan on using that while hooked up to shore power to top off the battery. I dont have solar but if you do, that will also top off your lithium.
    Steph & Lise
    2019 F150 Lariat 2.7 EB
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  6. #6
    Seasoned Camper
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    Quote Originally Posted by docque View Post
    In theory, I could get a 100% charge on the battery with the Stock converter and the solar panels set to lithium. From what I read the solar set up should charge a 100AH LifePO4 (from 0%) in about ten hours. Since there is no drain on the battery when plugged into shore power I would assume the battery could get to 100%.
    If you have a 12v fridge and stock solar, you will most likely never reach 100% charge until you turn everything off. Since the stock charger will go into float mode (essentially stop charging) long before you reach full charge, the solar charge controller will end up powering the refrigerator instead of fully charging the battery. By adding the third charging source, you will be providing more power than the fridge draws and will be able to achieve 100% charge.

    I am currently using a 200ah LiFePo4 battery with the stock 165w solar panel (charge controller set to lithium) and stock converter. With full sun, I can see the SOC go up (BMS shows the battery taking a charge). As soon as the sun goes down, the BMS shows negative amperage which tells me the refrigerator is being powered by the battery and not the converter. As a test, I turned on all of the 12v lights inside and out one night and added a bunch of stuff to the refrigerator and freezer to make sure it was running at full capacity. The battery continued to discharge until it reached 67% SOC then began to receive a significant charge from the converter.
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  7. #7
    Site Team Soundsailor's Avatar
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    Yes, I have a separate charger that I use to top off my LiFePo4 battery bank and it works fine alongside the converter/charger and solar.
    Stephen and Judy
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