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Battery Re-Calibration

Discussion in 'Inspire 1 Discussion' started by Quadpilot, Aug 9, 2015.

  1. Quadpilot

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    There seems to be a lot of confusion about re-calibrating batteries with the release notes of FW 1.3.0 stating to take batteries down to 5% then fully charging back to 100% to bring batteries back up to full capacity (4500mAH for a TB47). In my experience, 5% does not work, since after doing 5 TB47s that way with FW 1.3.0 I saw anywhere from 4100-4400 mAH capacity after charging them back to full.

    So I did some research and found a post by @mixmaven on RCGroups Inspire thread here who stated that he found out from a DJI battery expert that the trick is to get the lowest cell voltage down to 3.30V, which in my case meant bringing the batteries to 0% (This has been confirmed by RCGroups DJI Forum Support @blade strike). Even then, once my motors stopped, lowest voltage climbed to around 3.40-3.45V before the voltage drained to 3.30V.

    Easiest way I found to do this: Fly a fully charged battery down to around 20% (turn your battery warnings down to 15% and 10% respectively), then hover just above ground with LG down and wait for the RTH message, cancel it, and when you get the critical battery warning at 10% and the craft wants to land, just hold the throttle up to hover until it shows 3.3V (probably lower than 5% showing) and let it land. Once the motors stop, the cells will probably increase about .10V, so just leave it powered on until you see 3.30V on the lowest cell. Be mindful of battery temp while doing this, it did climb pretty high in this procedure. If in the field and once the motors stop, take off the props and put Inspire in front of the A/C vents in your vehicle. The trick, once again, is to discharge in one cycle down to the desired voltage, leaving the battery on the whole time.

    That worked for me. Upon recharge to full, all my batteries showed a full 4500 mAH capacity. As mentioned elsewhere, battery life will probably drop a couple percentage points from previous value after the calibration. Since calibration, my impression is that I've gained about a minute or so in flight time on my batteries. :D

    Don't forget to reset your battery warning levels once you go fly again!
     
    #1 Quadpilot, Aug 9, 2015
    Last edited: Aug 10, 2015
  2. Scotflieger

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    Thank you for reiterating the process. I tried to make this clear in the first 1.3.0.0 post but people don't read and (or wish to) understand simple directions. They try to read too much into it.
     
  3. pfanni

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    How do I see if the re-calibration was successfull.
    I flew until 2%, Battery was very very hot. AC in the car was very helpfull to cool down the battery.

    Greetings from Germany.
     
  4. Scotflieger

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    As @Quadpilot says, your will see the max battery charge value (mAh) in the App Battery screen show a value close to the rated value for your battery 4500mAh for TB47 and 5700mAh for the TB48. Make sure you allow your batteries to cool to ambient temperature before re-charging them.
     
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  5. Quadpilot

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    The battery will get very hot. A couple of mine reached 56 deg C, which is higher than DJI specifies for battery operating temp, but it didn't seem to harm them. Cooling them with A/C will help. The measure of whether it worked is that after a full charge the capacity should reflect the full rated value, as posted above by @Scotflieger.
     
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  6. SultanGris

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    Did they not previously show full capacity? How many times were they charged and how far off were they? I have three tb47s charged 36 times and two still show full capacity 100% life and one is 96% life and showing 200ma less than full capacity at 100% charged. I'm running older firmware.
     
  7. Quadpilot

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    If it's showing 200 mAH less than full capacity at 100% charge, then it needs re-calibration.
     
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  8. Scotflieger

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    You should not need a recalibration if you are still using the older firmware. The values displayed are likely to be accurate. Your one battery with 96% will usually indicate that it is ageing faster due to being over stressed or having a weak cell. You should do the recharge deep cycle every 10 to 20 charges.

    The latest FW 1.3.0.0 has changed the way the battery discharge profile is modelled. I suspect this is linked the the sudden death reports that users have reported. The recalibration should be carried out AFTER UPDATING THE FW (I emphasise to stop the obvious question of when) as you will likely find that the maximum capacity will drop slightly (200-400mAh) and flight times (2-3 mins). The life remaining will also show a 'realistic' drop of several percent.
     
  9. Scotflieger

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    Not really. This is simply the cliff at the bottom end of the battery power curve.
     
  10. SultanGris

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    Right, I was just curious if your guys batteries were dropping total capacity with use and if so after how many charge cycles were you seeing how much of a drop, but I guess youre saying its the new firmware update that causes them to drop and the re calibration fixes them, is that correct?
     
  11. Scotflieger

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    After several attempts to get the process correct and continuous, all my battery maximum charge returned to near their rated charge. The battery life did lose a few percentage points.
     
  12. mixmaven

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    I was like "what did I do now..." :)

    Didn't know you could tag people. Nice @Quadpilot Hopefully it is helping.
     
  13. SultanGris

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    I understand this, but my question is what charge rare were they showing before you did this and how many times have they been charged? Thanks
     
  14. Scotflieger

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    I have updated 4 batteries to FW 1.3.0.0 (beta standard): 2 x TB47 and 2 x TB48. I did not record in my battery log the max charge before the FW update but I did before the recalibration. The data recorded is:

    Batt 1 - TB47 - total charges 46
    before FW update 90% life,
    after FW update 92% life, max charge 4402 mAh
    after recal 90% life, max charge 4461 mAh

    Batt 2 - TB47 - total charges 34
    before FW update 97% life
    after FW update 94% life, max charge 4377 mAh
    after recal 93% life, max charge 4474 mAh

    Batt 3 - TB48 - total charges 26
    before FW update 96% life, max charge 5511 mAh
    after FW update 97% life, max charge 5473 mAh
    after recal 95% life, max charge 5488 mAh

    Batt 4 - TB48 - total charges 21
    before FW update 98% life
    after FW update 96% life, max charge 5488 mAh
    after recal 95% life, max charge 5625 mAh
     
  15. SultanGris

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    Ok thanks. Interesting stats. At 36 charges two of mine are identical at 100% life and still full charge capacity, the other is 96% life with a couple hundred ma less than full capacity full charge. I'll have to check if firmware versions are different or something, was just trying to figure out why one is different.
     
  16. Scotflieger

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    My battery 2 has a weak cell 4 (-0.3V) which I will be keeping a good eye on. It is the one the turns red with the GO app 2.0.0 towards the end of a flight (30-20%).
     
  17. SultanGris

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    My cells only vary by .1 or .01, I forget how many decimal places display
     
  18. Adamastor

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    Hey everyone...

    Also had batteries misbehaving after the latest firmware update.
    Followed Quadpilot's advice in the first post and did a re-calibrate of my batteries.
    One of my TB47s refused to go back up to 100% and 4500mAh even after running down to 5% multiple times.

    Then I noticed there is a new version of the Inspire 1 User Manual (1.4) and decided to stick to my trusty "credo" - "when all else fails, read the instructions"...
    On page 22 of the manual you will find this - "How to discharge your Intelligent Flight Battery".

    I followed the instructions and allowed the aircraft to switch off by itself, recharged and voilĂ ! Battery back to 100% and 4500mAh
     
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  19. AlanVT

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    All this for 1 minute of flight time? Seems like a real wa
     
  20. AlanVT

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    All this for 1 minute of flight time! Seems like a true waste of time and effort. Just change batteries and move on.