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Battery Cell Broken

Discussion in 'Pro/Adv Discussion' started by tome, Apr 17, 2016.

  1. tome

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    Had an interesting issue today. Went to charge my battery which has been sitting for a couple months now and when it finished charging the 3rd LED was blinking twice then off, pause, repeat. I pushed the on button and the battery showed all 4 bars. When I turned on the remote and powered up the P3 I get this message:

    "Battery Cell Broken", "Stop using battery and contact DJI customer service"

    Well, I did contact customer service so I'll see what they advise. The battery has only been used probably a dozen times.

    I tried another charging cycle but the same thing happens at the end. I was thinking I would discharge the pack and try again, but I can't run the P3 at all as the remote won't do anything at all when that battery is in the P3. So I'll wait to see what DJI says about it before attempting to discharge the battery manually.
     
  2. Phantom fool

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    That sucks.

    I wouldn't fly with a broken cell anyway
     
  3. alokbhargava

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    I had a strange battery behavior today. Battery was discharged to 16% during flight and when I put it to charging I noticed that last LED started blinking and not the first one. First 3 LEDs were off. I too it out of charger and put it to further discharge and rest. Next charging went smooth. I will analyze the details again before using my battery as I don't want to lose my bird because of it.
     
  4. tome

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    DJI replied today. They said that it would appear the battery has a bad cell. They suggested that I try the firmware update again on that battery. I did that and I put the battery in the charger and it seemed to charge and then the LEDs turned off. However, when I put it back in the P3 I still get bad cell. The second cell in the pack is very slightly below the other three. DJI says it is out of warranty and even though it has only been used exactly 16 times I am screwed. New battery time.

    I was able to get the motors to fire up and so I discharged the pack down to 4%, let cool down and then recharged. Again, this time, it seemed to charge up fine (no lights when complete). But once in the P3 it says bad cell. The voltage difference is only about 0.1V and the "bad cell" discharges down at the same rate as the other's. It appears it just won't get to max voltage with the other's for some reason. I have a couple good LiPo chargers so since I am hosed anyway, I might take the battery apart and see if I can charge the bad cell independently to match the others.

    Such is (battery) life...
     
  5. Geblo

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    The blinking light indicates the battery is to hot, over 40 degrees C.
     
  6. tome

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    Spent a bunch of time trying to get the one cell to charge but it isn't happening. So I took the battery apart. The cells all appear to be fine (no bulges or anything). Unfortunately, the cells are glued together in pairs and one of the inside cells is the one that is not being fully charged. So it will probably require some heat to get the cells apart which is always a fine line to be walking. It could also be that the transistor inside the Ti BQ30Z55 battery controller chip that controls balance charging for that cell has blown or the dissipation resistor on that balance lead is bad. Attached are some pics of the 4S configuration and bms. IMG_2669.JPG IMG_2668.JPG