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FAQ: Charging Batteries

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    #16
    Here's a schematic of BMS I've wired up and personally watched balance.
    D167-16S-Li-ion BesTech Power datasheet.pdf

    I don't remember anything too specific but the bleed resistors turned on around 4.25V and turned off around 4.17V, IIRC?

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    • mrm
      mrm commented
      Editing a comment
      Kocho, "Or maybe your charger is always charging to full regardless of the 80 or 90% setting, so some balancing is always occuring at the end of the charge?" No, the pack is showing what it should be (after charging to 80 or 90%). The amount of charge has been verified with 3 different meters. My point; it is balancing regardless of charge level. If the battery was NOT balancing(and the banks levels were off) the charger would not shut down, or take a REALLY long time to. I think this "have to" charge to full (to balance) is because full charge deteriorates the battery. If you don't need a new battery, you won't buy a NEW one. Please someone, show some documentation, prove me wrong. I WANT to know.

    #17
    mrm: I do not want to have to start locking these threads and deleting posts, but the knowledgebase section of this forum is for official documentation used by Luna, not for your personal theories. If you wish to debate take it to the batteries section of the forum. In preparation of this, feel free to contact as many BMS manufacturers as you like and ask them how their balancing works, in order to prove some sort of standard bms operation (we use dozens of different bms from many different factories). I am sure you will find what we are describing is pretty much standard operation. Furthermore you can disconnect your bms and draw down one of the cell banks while it's at 50% or whatever, plug back in your bms and see for yourself whether it balances without charging to 100%. If you have this information then it is knowledge and appropriate for adding to the relevant knowledgebase but until then it is simply conjecture.

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    • mrm
      mrm commented
      Editing a comment
      It was said "just my observations" I never said scientific (validated) proof. I'm looking for scientific (validated) proof.

    • paxtana
      paxtana commented
      Editing a comment
      Implying our recommendations are intended to prematurely wear out your pack is not an observation, it is an accusation. The datasheet above from a well known BMS manufacturer explicitly states the voltage it balances at, as do many other datasheets. The burden of proof is not on us when stating common knowledge, it would be on you to disprove it.

      The functionality you describe typically only exists in BMS that costs around $150 each. We are working with an engineer to bring an affordable alternative to market but it'll be a while before then. When we do it will be a selling point, not something we hide from the public.

      Does your affordable pack happen to have an expensive BMS that works differently than typical? I don't know, maybe but I doubt it. It is not like you cannot find out. Or maybe your pack stayed in balance because you are not deeply discharging it. We don't even know the model of the pack you are talking about let alone important details like that.

    #18
    " my 52V 11.5A PF Cell Panasonic battery " = Luna Pack. And yes, I don't let my packs discharge deeply. I shut my packs down at 45V, +/-. The only BMS I was referring to is the one in the Luna pack.

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    • paxtana
      paxtana commented
      Editing a comment
      That's not a model. There's 3 different models fitting that description, using several different bms depending on when it was built

    #19
    I no longer have that battery. All I can find (checking my orders) is 52V Panasonic PF 11.5Ah Performance Pack. It was purchased 3/16. If I recall correctly, it was built about 1/16. Maybe it had the GOOD BMS. All I can say is that it always charged and discharged (each bank) within .01V of each other no matter what charge level I set it to charge. But frankly, it was a disappointment, getting only about 75% of the range of my 8Ah packs(under the same riding conditions). My current GA's are FANTASTIC.

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      #20
      Please direct any questions to this section: https://electricbike.com/forum/forum/batteries/18650

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        #21
        Can someone clarify if it matters whether the switch on battery cases should be "on" or "off" for charging? And if it matters, why? I can see why you might want to have it off if the pack is on the bike and connected to the electronics there, not interested I that - just want to know if the charging and balancing is affected by the battery switch being on or off. Thanks! Asking here, because this information should be in the how-to thread.

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          #22
          The answer varies depending on the battery. They all come from different factories with different bms, case etc.
          Generally you want the switch to be on when charging or it may not take a full charge. We had a few support issues where that was the case. With others, you would need it to be off, then plugged in, then flipped on. I would not be surprised to learn there's other packs out there that need to be switched off to take a charge, for whatever reason. And there's definitely a bunch where it does not seem to affect charging at all. Best advice is to get to know your pack and what works.

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            #23
            Interesting. I've always had mine (48V carbon shark) off, only because it made sense to me to do it that way. I'll have to try it turned on next time I charge.

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              #24
              I found This Image quite useful in Getting the most "Battery Cycle Life From Li-Ion Cells"

              I'm personally Using a I-Charger 4010 Duo Charger/Discharger/Balancer (NO BMS Needed) for Charging/Balancing a 15S/10P Battery Pack to "4.0v per cell" giving a Total Voltage of 60V and Significally increasing my Battery Life span, possibly 3 X more Cycle Life (upto 1,500 Cycles)

              Batteries are in Two Physical Parts : Battery 1 - 8S/10P & Battery 2 - 7S/10P ( NCR18650GA cells) 3500mAh Rating (60V at 35AH)

              A solid State Relay then switches together in series powered by a 3S/3P (Aux Battery) Off position Electrically isolates 2 x battery packs from each other so I-Charger can safely charge/Balance both Packs seperatly.

              The Relay latching is controlled by a 3 position Key Switch (Off-Charging/Balancing, On- EEB Operating, Lights- Running & Headlight for Night)

              I included a "Small scale Test" to prove that it will operate safely and Correctly (Photo Below)

              using 2 x 3S Li-Po Batteries to substitute Li-Ion Packs (Below) Currently building both Li-Ion Packs (see my battery build post)

              Note- Photo is not showing Batteries but they connect to each 2 x Deans Connector
              Last edited by Patrick1977; 1 week ago.

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