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Taking Off With Less Than 100% Battery?

Discussion in 'Pro/Adv Discussion' started by Just Mark, Sep 25, 2016.

  1. Just Mark

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    In the manual for the P3A, it says "Don't take off with a battery less than 100%" (or something very similar to that).

    So am I really risking something if I take off with a battery at 70% or 65%? Does the take-off portion of a flight strain a battery so much that it is particularly dangerous to take off with a battery closer to 50% than 100%?

    I try to fly responsibly and cautiously. I would rather NOT fly over people or houses or cars if I DON'T have to. (What's the saying; "There are old pilots, and there are bold pilots, but there are no old bold pilots")

    So I often will put the craft up and fly / photograph one side of a park quickly, bring the bird down, walk it over to the other side of the park, and then put it up again. So that second time I put it up, I will be taking off with 60% or 70% battery life.

    Is that wrong?

    Yes, I know I COULD fly it over people and houses (and I sometimes do) and I know that the possibility of the P3A falling from the sky is low as long as I have done my pre-flight check. Still I would rather error on the side of caution.

    My flights tend to be short; maybe two or three short flights of 5 to 7 minutes on one battery, then change to my second battery.

    Thanks in advance.
     
  2. NimpoCub

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    I believe that the thing is, if you take off with less than 100% charge, the battery will lose it's power faster (for the remaining charge). So, do it but keep a closer eye on your voltage.
     
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  3. alokbhargava

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    Its not that you can not start flying with 65% charged battery. The main problem is in the phantom remaining battery calculations. It is not able to calculate remaining battery correctly if you start your flights say with 65%. You can start with 100%, let it land at 65%, don't switch off phantom and initiate another flight, thats OK as phantom will remember last readings and the capacity loss rate point on the curve.
     
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  4. Just Mark

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    Ok, so just to make sure I understand you (I am a slow learner so I like to double check everything):

    As long as I leave the craft (and the transmitter and the app) ON while walking it over to my new launch spot, it should be ok to take off with only 70% or 65% battery, right?

    And is this a sound strategy when it comes to utmost safety? I know with "real" airplanes that landings and take-offs are the most dangerous. I like to fly with an abundance of caution.
     
  5. Just Mark

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    Ahhh... I remember reading that somewhere... I think they said the battery discharge rate from 75% down to 50% is faster than the battery discharge rate from 100% down to 75% (or something like that). Even though technically they are both a 25% drop in remaining capacity.
     
  6. alokbhargava

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    Yes you understood correctly.

    I normally don't do this as I like to fly until battery drains down to the low level. Some of the professional photographers wanted this and have claimed to have done it successfully. This may be a good strategy but I keep extra batteries in case I need to land.
     
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  7. Just Mark

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    Thank You!

    P.S. Didn't realize you are located in The City. I am across the GGB over in Marin.
     
  8. alokbhargava

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    We will meet one day. :)
     
  9. flyNfrank

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    The easiest way to explain the battery situation is, the aircraft requires a set amount of voltage to operate. Regardless of how much the battery displays for the remaining charge, you have the ability to exhaust the voltage below the required voltage needed. So now the more the battery has drained from flying, the faster or sooner you will reach that "No Longer Safe Voltage Amount" I mentioned as being required. Flying into a strong headwind at full throttle would most likely end in a failure.

    If at any point you feel you don't trust the dji battery, just know you have a option to do a dual battery mod that several can point you to the info.
     
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  10. Cactus Wren

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    It does it seem almost scandalous that DJI charges you SO much ($169.00 through their online store, but cheaper with other retailers) for batteries that only give you about 15 to 20 of comfortable flight time. It's the major downside to these drones for me.


    Sent from my iPad using PhantomPilots
     
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  11. NimpoCub

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    No matter what you fly, you must keep aware of your "fuel".
    Batteries are (still) heavy. Buy several.
     
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  12. Meta4

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    That's the limit of current (affordable) battery technology.
    It's not like other manufacturers are offering 30+ minute performance.
    When the P2 was released with 20 minute flight times, it was a breakthrough.
     
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  13. Just Mark

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    Thanks to everyone who has replied so far.

    I guess to clarify my question just a little bit further, would taking off require MORE voltage than normal flight?

    I tend to fly VERY conservatively.

    And will probably buy a THIRD battery so as to not tempt fate.
     
  14. Just Mark

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    Thank you.

    Yes, I appreciate your message that as capacity lessens, the voltage drops as well, and while the app might display a certain percentage of capacity remaining, there might be flight maneuvers which require more voltage than the battery can put out when the capacity gets below a certain point.

    Do you have a personal cut-off limit in terms of remaining capacity where you try to land the bird down ASAP? Meaning, at what point do you look for the absolute closest spot to the craft to put her down?
     
  15. msinger

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    Check out this thread.
     
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  16. cyberthingy

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    Maybe I'm pressing my luck but I have flown after takeoff with less than 80% quite a few times. This however has been after a previous short flight on the same battery that was within a day or hours of the subsequent flight. I probably would not try it at anything less than 50%. I also very rarely fly below 30% capacity. I would agree with others that monitoring the voltage rather than focusing solely on the percentage left is a lot safer. I also have 4 batteries so if they too are fully charged then I am more likely to swap them as a first option. It seems that battery drain rates are an inexact science and caution should always prevail but sometimes risk taking is part of the game if you need just a few minutes more in the air to get your shots.
     
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  17. Just Mark

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    Thank you for the link!
     
  18. Just Mark

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    Thank you for your thoughts.
     
  19. flyNfrank

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    You should concerned at 3.3 per each battery cell if looking the GO app. If you are in a heavy use and left off the stick the volts will recover. But the longer you fly, the less it will recover. Set the option to show voltage on main screen and keep an eye on it.
     
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  20. Just Mark

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    Will Do! thanks again!