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$1000- dollar lession learned

Discussion in 'Phantom 2 Vision + Discussion' started by yali, Jul 24, 2014.

  1. yali

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    Lession Learned: RTH will stop working when battery hit 20 %
    20% was thought to be enough for a RTH mission until I lost one in a river !
     
  2. cahutch

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    Sorry to hear that. That's a hard lesson.

    I thought it was 15% for that to happen.
    What is your critical battery threshold set to in the Phantom Assistant? The default level is 15% but it can be raised or lowered as low as 12%

    At critical battery level it will auto land wherever it is.
    Maybe it started back but got to 15% before it could reach home.? In my limited experience, there's not much time between 20 and 15%. No more than a minute or two.

    I'm told that if you have manual control at critical battery level, you can throttle up and keep it in the air, but when flying on auto-pilot, it will auto land wherever it is.

    I appreciate you posting this lesson for the benefit of others. I will keep it in mind myself and caution others to read as much as you can on the functions and operation of the phantom so you know what to expect in every situation.
     
  3. cahutch

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    Makes me consider lowering my critical battery threshold to 12% just to prevent auto landing until there's no other choice.
    I don't see a downside except that running the battery that low is not good for the battery longevity.
     
  4. Awilson18

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    This is why I bring mine home at 30%...
     
  5. cahutch

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    +1
    At 30% you should be home or on your way home.
     
  6. Dirty Bird

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    Very sorry to hear that. Did you raise your second battery threshold to 20% from the 15% default? At the second limit, the bird will begin descending, but you can still force it to maintain altitude if you hold the throttle up at 90% or more up. I have my second alarm set for 12%, and its a good idea to be close to home and ready to land by 15=20%.
     
  7. kymedic121

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    I am still overly cautious and will probably will always remain so. When that sucker alarms at 30% I am headed home and landing ASAP.
     
  8. samd012

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    Actually you are suppose to drain your battery down to 8% or below every 20 uses per page 10 of the manual.

    I always head straight home at the by the time the 30% alarm chimes in, have not pushed it much yet.
     
  9. cahutch

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    I changed my critical alarm threshold to the lowest possible value (12%) tonight in an effort to avoid this situation. I don't see a downside to it.
    It's not much but it's an extra 3% before it starts to auto-land. More time is always better.

    I drained a battery down to 8% tonight, so I know she'll stay in the air that long if I keep the throttle up.
     
  10. RedRyderMedia

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    I don't understand the need to fly below 30%.

    When the horn goes off, my heart rate goes up......I look to land before getting to 30%.

    Go buy a second or third battery and live to fly another day.

    This seems to be an unnecessary expensive lesson to learn......particularly when your Phantom is on the other side of a River or tree or building or anything that represents a barrier. I just don't get it.

    Sorry to hear you lost your Phantom, but learn some simple common sense......OBTW, don't by yourself a gun next.
     
  11. DBS

    DBS

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    Don't know where you're getting that from but it's not really true... 12% on the Phantom battery meter doesn't mean 12% of the lipo itself... it's more of a flight time meter telling you how long you have to get home and land... I fly mine down to 0% on a regular basis and they still show well above 10 volts after landing and 99% healthy on the assistant software after more than 60 flights ... DJI manual tells you to run it down blow 8% or until the battery won't turn on any more every 20 flights or so to keep the battery in best condition... I do it even more often than that and now I notice my flight times are longer before it starts to auto descend.
     
  12. Mori55

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    Why didn't you fly it home instead of RTH.
     
  13. yali

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    I turned off my transmitter for the RTH when it is reaching 20 % and waited. when I realized it won't come back anymore, it was too late.
    I could not see it, so, hadno idea what it was doing, so did not throttle it up. ... When I went to the Find My Phantom for its location, it's icon was in the middle of a river. I asked one standby and he said he saw it hovered above the water for a few seconds and slowly descended into water. :( never saw it anymore. It was only on its 4th flight : )
     
  14. EMCSQUAR

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    Not a good idea to do when flying. I do it when it's in front of me and on the ground.
     
  15. happydays

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    Ouch!
     
  16. BlackTracer

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    +100

    I am sorry to hear about this loss. This is just more sauce for the knowledge goose. On my very first phantom flight (P2V), I glossed over this auto-land "feature" in the manual. So I was flying along at 20% thinking "I've got plenty of battery left I'll just keep flying". Little did I know what would happen at 15%. Luckily it was right in front of me at 10 ft height and just auto landed right before my eyes. Had no idea at the time that throttle up was even an option. After that, went home and scoured the manual again and found the part about auto landing at second battery alarm level. Then it all became crystal clear what had happened.
     
  17. cahutch

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    We'll if that's true (and I believe you) then why in the world would DJI limit the minimum value at 12%? The only logical reason for the "feature" is to give you a "gentle" landing before the battery dies completely and you fall out of the air. With 12-15% left, you still have time, and auto landing can't be any advantage at all until 2-5%

    How soon are you measuring that 10 volts? If more than a few seconds, I suspect you're seeing battery rebound after the load is removed. 0% is probably 9 volts under load.
     
  18. Mori55

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    I would have used home lock , if I didn't see it very well. Tough lesson to learn.
     
  19. BlackTracer

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    This may not have mattered. His craft was lost because it dropped below critical battery level and auto landed on its way home. Pretty sure he would have lost it either with HL or RTH.
     
  20. tedw123

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    Although manual says that, I've heard many professionals say draining these type batteries as low as 8% could actually do more harm than good, who knows best answer?