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Automatic RTH and low battery warning with 73% battery?

Discussion in 'Pro/Adv Discussion' started by iahphantom, Jun 13, 2015.

  1. iahphantom

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    Can someone please help me understand what happened ?

    [​IMG]

    [​IMG]

    How can it initiate RTH and give me a low battery warning when I have 73% battery? Does it take into account the distance from home point ?
     
  2. msinger

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    Correct. The yellow "H" on the top bar is the point where you should turn around and start coming back. Otherwise, you might not have enough power to get back before your battery reaches the low battery level.
     
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  3. envisionabove

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    First thing that came to mind for me was the need to get back? But yeah 73% does not compute.
    When it came back did you shut down and then recheck the battery?
    How did the lights look on the bars when you pressed the button?

    Yeah 17.+ mins total with the 10% critical now it makes sense.
     
  4. iahphantom

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    That makes total sense as to why it was about 1500 feet short of the home point and landed safely
     
  5. iahphantom

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    It didn't make it to the home point. It landed about 1500 feet away once it reached 10%
     
  6. envisionabove

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    That's the emergency Auto land bet your glad you were not over water. :)
     
  7. Serpent

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    By my calculation you had covered about 1KM per minute straight out from your home point. If this is correct then you did well to still have a signal at 5KM.
    Given wind factor it's probably a reasonable safety margin for it to want to come home.
    \
     
  8. iahphantom

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    At the time it didn't make sense. So I canceled the RTH. But oh man did it make a whole lot of sense when I was 5000 ft out and realized what was about to happen
     
  9. tonyt76

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    Just curious... your flight log says 795ft height? Doesn't the FAA regulate us to 400ft max?
     
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  10. iahphantom

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    Suggested. But it wasn't intentional.
     
  11. RoyVa

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    Best thing to do is calculate distance out and back for flight time. Then you will know how far you can do and be able to return safely. You need a little margin too to make it back.
     
  12. Nannerz

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    curious if it was the stock battery or one of the new ones they're sending out.

    Wonder if the new batteries they're pumping out have some flaws....in order to "cash in" and meet demand?...hmmm?

    Alot of sudden battery "freak out" stories surfacing....
     
  13. Brianroberts

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    First off, this sounds like a veiled scolding. Secondly, is the indicated alt MSL or AGL? FAA guidelines are in regards to AGL, and I really don't know what the pilot app reading is.

    Also, FAA only encourages their guidelines of 400ft for model aircraft. Class G airspace is pretty unrestricted and varies, but is generally 1200ft AGL. Of course it's wise to follow their guidelines to not cause unneeded issues, but they are just guidelines at this point.
     
  14. caffeinated

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    Read the thread title and thought 'youch'. Saw the first pic and went 'Jeepers! Fair call DJI!'
     
  15. Phantom751874

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    How many cycles does the battery have on it? Believe DJi recommends taking a battery from 100% to 8% every 20 full cycles. This is to "calibrate" the battery so that it knows the reported battery percentage is accurate.

    Apple and and many other manufacturers that make devices with LiPO batteries recommend the same kind of calibrations albeit with different cycle counts.

    And make sure on long flights out like that you always go against the wind on the way out. DJi's calculation on when you need to turn around and head home (the bar) is great but it doesn't really know you went out against a 15mph headwind and that on your return trip you'll be able to easily double your speed coming back. This builds in a bit of a safety for you.
     
  16. tonyt76

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    Brian,

    I was not scolding anyone, I was simply asking a question.
     
  17. Brianroberts

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    Then I am curious, what was the intent of the question?
     
  18. tonyt76

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    I am new to flying and trying to learn. When I saw the picture of max height and saw 795ft I thought, doesn't that contradict all of the posts here stating that 400ft is the max allowed by the FAA? It is for my own knowledge. I want to ensure that I am following the proper guidelines.
     
  19. Brianroberts

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    Fair enough, sorry I misinterpreted the intent of your post.

    The FAA guidelines state to stay under 400ft. They are guidelines and not laws. It's a good idea to stay below this if you don't want to stir up trouble. However, class G airspace (typically under 1,200 ft AGL which means Above Ground Level) is not really regulated, although it IS the FAAs jurisdiction. Class G is much shorter near and around airports and other areas. You could take a look at aeronautical charts if you are really curious, but there is no need unless you are an actual pilot at this time.

    I'd recommend staying under or around 400ft unless you are in the middle of no where where you will not draw attention. If someone complains and the cops come, it's easier if you just say that FAA guidelines say whatever, and you are adhering to them. It's not that you'd be breaking any laws necessarily, it's just an easier argument to authorities.

    My serikous question though, and I don't have my Phantom here to see, is the reading in the pilot app AGL (Above Ground Level) or MSL (above Mean Sea Level)?

    EDIT: I THINK that the phantom has a max ceiling (Pilot app settings) of 400m AGL, but I could be wrong. This is just a bit above 1,200ft
     
  20. N017RW

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    The altitude is reported as height above take-off elevation thus it is a relative measurement to the ground and not exact.