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Setting boost reconnect charge voltage

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  • Setting boost reconnect charge voltage

    I have my charge controller almost completely setup for my battle born lithium batteries. The only setting I'm not sure about is the boost/absorption reconnect charge voltage. I'm guessing this is the voltage the batteries need to hit before the charge controller starts charging the batteries again? Factory is set to 13.2 volts which I believe is around 70% SoC. If kept at this setting, will the batteries not charge again until 70% SoC or lower? Is this a good number or should it be set higher? I plan to contact battle born about this setting but I'd also like other people's opinion on this.

  • #2
    After doing some more reading I think I better understand this now. I also believe I should have provided more information so here it is.
    Absorption: 14.4v
    Float: 13.6v
    Equalization: off
    Boost Duration: 40 minutes (20 mins per battery based on what battle born is telling me)

    These are all numbers I received from Battle Born.

    Am I better off turning my boost off completely and just doing bulk charge then float? I understand the batteries won't fully charge doing this but it will reduce the risk of overcharging the batteries. They have a built in BMS so I'm not sure I even need to worry about this?

    They also state the batteries do not require a float charge. But to my understanding, it wouldnt be smart of me to turn off my float charge if I'm charging the batteries with solar. Otherwise the batteries could be charged at noon and the controller will cut off power. Then if my fridge or something kicks on, I'd be using strictly battery power until I hit my boost reconnect voltage of 13.2v even though I have plenty of sun power there to be used.



    • #3
      This is called outsmarting your BMS because you know better and also know it's going to rain for the next 4 days

      You have to know exactly how your BMS works, how / when it shunts, disconnects (you only want it to disconnect in an emergency) and if you want to have a rain boost.

      Adding 20 min "boost", does not seem right, 40 min would be too long for 2 batteries, they should both share the power.

      You are going to have to solve it on your own, because B.B, may never give you a correct answer.

      Once you know the chemistry makeup of your cells, that can be used to develop your own safe voltage setpoints
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



      • #4
        Thank you for the reply. I asked BB about just shutting off the absorption charge and they stated I should not do that. They stated, "This ensures that the batteries get to 100% full and you will want to do this at least a couple times a month when in regular use. This will internally balance the cells."
        I'm not really worried about getting 100% charge, 90% would be just fine. I'm not really worried about shortening the life of the batteries if charging them to 100% either. This will be for an off the grid cabin which at most would be used a couple days a week. So the batteries might cycle 100 times a year. If they last 3,000-5,000 cycles as stated, I would not have to replace these for a very long time. They also have a 10 year warranty, so my original plan was to set the charger as they stated and let it ride.....