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Nearly put inspire in ocean

Discussion in 'Inspire 1 Help' started by Wiski23, Mar 10, 2015.

  1. Wiski23

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    View attachment 746 View attachment 747 View attachment 746 Hi pretty alarming day, was cruising around the harbour on this fine Auckland day. No wind just blue skies. I was filming boats cruising about from a wharf.
    I had 25% battery left, the inspire was only 500 metres away so plenty of return battery, but out of nowhere with zero warning it started beeping battery critical. Then landing gear came down and it started to land in the ocean. Luckily I stayed calm and spotted a wharf near by. But for some reason the inspire wouldnt fly straight, I was looking at my height on my iPad,it was dropping fast! I managed to just make the wharf as it semi landed slid on the edge of the wharf.
    Luckily the near by wharf was a secure zone so I raced over in my van and they collected it. I was relieved but semi fuming to say the least as this shouldn't have happened.

    In my pictures you'll see the battery goes from 25% to 7% to 3% to 0% all in the space of less than a minute. Exactly 53 seconds to be precise going by the numbers on the iPad.

    I also have video.

    Why did the battery voltage drop?
    Why couldn't I control it?
    Would Dji have covered this if it went down?

    image.jpg image.jpg image.jpg image.jpg
     
    #1 Wiski23, Mar 10, 2015
    Last edited: Mar 10, 2015
  2. Kilrah

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    Many threads about the battery voltage drop, best would be to search for those as the reasons have been explained multiple times.
    You can control it, just differently (need 50% stick up to maintain alt).
     
  3. Wiski23

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    Will search that up. Still going to lodge this with dji, being 2 seconds away from loosing something worth 5k it's not something I'd expect and it shouldn't have happened.
     
  4. Kilrah

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    How many flights do you have?

    Did you follow the recommendation of doing a full discharge of a battery every 10-20 cycles (precisely meant to recalibrate the % meter that will otherwise get wrong with time)?

    Also the original battery warning is set at 35% and that's when you should land, anything beyond that would be your own responsibility.
     
  5. Wiski23

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    Yes i understand all of that. But at the end of the day the battery shouldnt have dropped from 25% to 0 in 53 seconds. I set my return to 20% which serves me well. This battery is new its had aprrox 4 charges so no it hasnt been discharged which I know about mate.
     
  6. Kilrah

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    Did you look at the detailed battery info page to see what the problem actually was, low voltage, dead cell or anything?
     
  7. Wiski23

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    No not as yet.
     
  8. RolandRSA

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    As a rule of thumb never go below 30%, I agree the battery should not suddenly drop from 25% to 7% but your dealing with a Lipo battery so it is always best to play it safe in my mind...just my two cents.
     
    m1ch1gan likes this.
  9. Tahoe Ed

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    I had something similar happen to me this week but I was flying in lower temps. I discharged all my lipos to 0-5% and did a full recharge. I checked the battery history and found nothing abnormal. I would be extremely careful when flying over water and land no later than 25%
     
  10. Wiski23

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    Yep im changing it back to 30%. I checked the batteries and they are all fine
     
  11. bradjward

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    Same thing happened to me over a lake this week. Went from ~40% to 7% critical warning in a matter of seconds, had to gun it back, barely made it off the water and across the road to where I was standing.
     
  12. jon b

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    First of all, nice recovery and congratulations. Seen the thread about battery drop, but all of those were in cold conditions (around and below freezing). Was it that cold? There is a very good write up in the mentioned thread about lipo chemistry and what to do/expect. There have been a number of posts about exactly this kind of occurrence.
     
  13. jhardway

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    I know the spec say that on a t47 (4500mha) battery you will get 18 min, there is enough people here flying these things so I would like to ask on there opinion, what do they think a good flight time is for that battery with the Inspire. I like to keep a time, I believe it can keep me more honest. The other day I flew mu I1 and got about 14 min out of it and the battery on the app was reading 25%
     
  14. Wiski23

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    28*celcius. Nice warm day
     
  15. The Editor

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    Very difficult to quantify but NEVER take a manufacturers battery timings as your guide (the same as a car manufacturers mpg figures..... it will never happen)
    Dependent on temperature, wind conditions and how aggressively you fly I would say anywhere between 14-16mins is about right. I land at 20% and regularly achieve 15 mins.
     
  16. jhardway

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    Ya so over the last few days I have been timing things out, and figured with constant movement flying at varying altitudes and speed. I believe I am looking at 13.5 min to hit the 30% mark and roughly 14.5min to be just on the north side of 20%. I am planning to do the same with my T48 battery and see what that is and I will post that results when done.

    best
     
  17. jon b

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    Thanks for doing this. Nice to have expected benchmarks to go by. Of course, temps and battery condition (to name a couple) have an effect. Then there's the mysterious voltage drop some have seen. 14 min is plenty of flight time for shooting per battery.

    for those who want to go the farthest they can, maybe a purpose build copter is the way to go exploring. Cheaper too should you calculate wrong.
     
  18. The Editor

    The Editor Moderator
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    I get between 18 and 19 mins comfortably with my TB48's. If I push it I can squeeze 20 mins out of one but that's running the pack down to around 18% which I don't like doing too often (unless I'm calibrating the battery)
     
    #18 The Editor, Mar 18, 2015
    Last edited: Mar 18, 2015
  19. Ferdi

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    Hey Wiski23. Glad you got your bird back safely! That is scary! How did you get permission to fly there? That's within the 4km no-fly radius of 4 heliports located in Auckland. I'm curious as I'd love to fly there for a client of mine, but with a $30,000 fine for breaking the airspace law I am hesitant to even think about flying there.
     
  20. Wiski23

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    It's all about who you know buddy.
     
    mdomeny likes this.