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4S2P "12V" Accessory Battery Pack HELP!

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  • 4S2P "12V" Accessory Battery Pack HELP!

    I'm brand new to learning how to construct and wire up Lithium battery packs. After trying to charge a couple packs using a lithium-specific car charger (and frying cells each time), I bought a hobby charger and some BMS'.

    Today I built my first 4S2P battery to power the stereo on my electric scooter. I followed a DIY guide from the internet for building the battery and connecting the BMS (Images attached). After everything was connected I took my multimeter to test the voltage:

    B+ to B2 = 4V
    B+ to B3 = 8V
    B+ to B4 = 12V
    B+ to B- = 16V
    P+ to P- = 16V

    I also tested the voltage on each battery and each series, which were all 4V. I then connected the pack to my Hobby Mate Lithium Charger (for 1S to 6S lithium batteries) and ran several settings, but none would work. Not LiIo or LiPO, not Charge or Discharge. Every time I try and start the charging the charger beeps several times and displays "Battery Check Disconnect". Disconnecting and re-connecting the battery does absolutely nothing.

    I got frustrated and connected the battery up to a standard SLA 3A charger... It connected and began charging immediately until it reached "Fully Charged". I tested each cell and all were functioning perfectly; however the SLA charger does not achieve a full 16V and thus could never bring this pack up to its full voltage.

    I would appreciate any help some of you experienced battery builders can offer on why I am not able to charge this batter pack using my Lithium charger. I can't figure out what I'm doing wrong. Thank you in advance for your feedback
    Attached Files

  • #2
    Follow up images
    Attached Files

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    • #3
      Based on the output wiring of my hobby charger for LiPo 3S batteries there are 4 wires. One for each of the Strings and one for the return circuit. Remember the BMS will "balance" each string so they charge up to equal levels.

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      • #4
        Smoking lithium batteries is very bad for your health. The hydrogen fluoride (HF) gets inside you, is odorless and depending on the amount, takes from a couple hours to a couple days to get you really sick. Unless you alert the hospital you were exposed to degrading lithium batteries, they can't figure why you are dieing.

        Hydrogen fluoride (HF) is a colorless gas or liquid substance. It is the principal source of fluorine, a feedstock for pharmaceuticals, polymers (Teflon) and assisting petrochemical industries. Hydrogen fluoride is a highly dangerous gas, forming corrosive and penetrating hydrofluoric acid with moisture. In large quantities, gas can cause blindness by destruction of the corneas.

        Interesting read:
        http://www.candlepowerforums.com/vb/...s-from-battery!!!
        30 min after exposure, coughing started !
        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

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

        Comment


        • #5
          Originally posted by Mike90250 View Post
          Smoking lithium batteries is very bad for your health. The hydrogen fluoride (HF) gets inside you, is odorless and depending on the amount, takes from a couple hours to a couple days to get you really sick. Unless you alert the hospital you were exposed to degrading lithium batteries, they can't figure why you are dieing.

          Hydrogen fluoride (HF) is a colorless gas or liquid substance. It is the principal source of fluorine, a feedstock for pharmaceuticals, polymers (Teflon) and assisting petrochemical industries. Hydrogen fluoride is a highly dangerous gas, forming corrosive and penetrating hydrofluoric acid with moisture. In large quantities, gas can cause blindness by destruction of the corneas.

          Interesting read:
          http://www.candlepowerforums.com/vb/...s-from-battery!!!
          30 min after exposure, coughing started !
          I have never had any smoking lithium batteries, nor any that caught on fire. Just a few that I killed (voltage wouldn't go past 1.5V or they wouldn't accept any amperage) in some experiments I ran with various chargers and charging methods. But thank you for the valuable information for anyone working with lithium batteries. You definitely want to be cautious with them.

          Comment


          • #6
            STOP. Have you verified the individual cell grouping voltages with a multimeter? The charger is balking because of that and/or the bms wiring.

            Most important is the shoddy DIY wiring. BAD. See your "straps"? And how there is only a sliver of cell sleeve material between the case and the positive terminal? One tiny hole develops, either from aging, or shrinkage / weakness in the sleeve and you have instant short. Your solder blobs nearly bridging between the positive terminal and casing don't inspire me either.

            I'm going to be brutal here in an attempt to keep you safe. Don't take this personally, but blindly following some project without really knowing what you are doing with lithium is not only dangerous to yourself, but also to others perhaps in your own household.

            I want to see you around. Don't fool around and come back from work / vacation and find your house burned down. Right now, you don't have the necessary skills to be safe.

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