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  1. dpackham

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    I've seen a few times a warning to not start a flight with a partially full battery... what's the reasoning behind that if I know I am doing so and have less time for flight? Like I just want to take a 5 minute flight?
     
  2. Dacon Productions

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    I took off many times with battery between 30% and 15% because I forgot a shot. The flight was very close to me but did not have any problems.
     
  3. SteveN76

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    I don't know but after all the horrible things I've heard happen here why chance it. You can get pretty high and far in 5 mins and if it falls it's could be a total loss.


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  4. phantom13flyer

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    Most problems occur with batteries that have begun their auto discharge cycle. Never use a battery that has been sitting around long enough to auto discharge . It's a good habit to charge your batteries an hour or 2 right before flying .


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  5. msinger

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    As long as you're not running firmware version 1.5, you shouldn't have any trouble with your battery shutting off mid-flight. When the battery reaches the critical low level, it'll auto land at its current location. In most cases, that gives the Phantom plenty of time to make it to the ground (or a tree/lake in some unfortunate cases).

    To answer your question, you can take off on a partially charged battery if you take care to land by the time the first battery cell reaches 3.4V. If you fly beyond that, you really need to know what you're doing because you can get into some tricky situations when trying to fly on batteries in the 3.0V - 3.3V range.

    As phantom13flyer pointed out, you should never use a battery that was last charged more than the number of days set in the "Aircraft Battery" section of DJI GO (see my screenshot below). For example, if you have that setting set to 10 days (the default setting) and you fully charged the battery 5 days ago, you could safely fly on it today. Or, if you used the battery for a few minutes yesterday and wanted to do a quick 5 minute flight tomorrow, that would be okay too.

    DJI-GO-Battery-Time-To-Discharge.jpg


    The most important point to keep in mind is that your battery will start to auto discharge when the button on the battery has not been pressed for whatever "Time to Discharge" time period is set in DJI GO. After that auto discharge process has started, you should not fly with that battery again until you fully charge it.
     
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  6. jwt873

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    I once plugged in the wrong battery and took off with one that only had a 40% charge. It worked fine. The only thing was that I was surprised to see a low battery warning pop up so soon after takeoff. I returned and landed with no problems.

    I was only 1500 feet away when the battery warning appeared. I guess if I had been 3000+ feet away there might have been a problem getting back.

    Since then tapping the battery button to check the charge has become part of my pre-flight checklist.
     
  7. Michael Stuart

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    What do you mean "as long as you're not running fw version 1.5"?


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  8. atariman

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    I have flown with 40% in batt. Just as long as u are aware u have less time all is good.


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  9. msinger

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    It contains an undocumented bug that could allow the battery to shut off mid-flight.
     
  10. John Locke

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    YES, DJI was pretty adamant at CES when I asked them about the cases of mid flight power shut down, they said never fly 1.5. However this was for phantom 3s.
     
    #10 John Locke, Jun 26, 2016
    Last edited: Jun 26, 2016
  11. Argyle

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    When they auto discharge what % do they go down to?


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  12. Norval

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    50%


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  13. Argyle

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    Good to know. Any special practice needed for long term storage?


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  14. Stealthmatt

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    The issue is with the auto discharge system. The battery slowly discharges and gets into a state that says 50% remaining, but when a load is put on it it doesn't have the grunt behind it and rapidly loses charge which can catch a pilot out.

    They have attempted to rectify this in newer firmware revisions by chaining the calculations of remaining battery, but it has still been known to occur.

    As long as the battery has not been auto discharged, you will be ok to fly at 50% capacity, but if its been auto discharged and sitting around, then you are better to charge it first.
     
  15. msinger

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    As far as I know, this issue did not show up in the P4 firmware yet. So, any P4 firmware is safe to use battery-wise. My 1.5 reference above only applies to the Phantom 3.
     
  16. henick

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    Lots of people seem to take an adverse stance to the half battery thing. Not sure why. Anybody that understands the issue of voltage sag exasperated by cold temperatures as evidenced by the content of the cold weather update would know that in ideal temperatures yeah, you can probably fly at low battery. But is it worth the possibility of anybody saying told ya? Probably not.

    Voltage sags to critical in less than ideal temperatures maybe caused by their intelligent crap trying to protect the cell. That's why they limited propulsion based on some sanity checking. People saying don't fly low battery are simply helping you sanity check whether you know why to do it or not. The reasoning of everything DJI did is fairly clear, IMO.
     
  17. John Locke

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    The key point msinger made was to watch your single cell voltage level. That's way more reliable than trusting the percentage bar for battery life. It's my belief DJIs algorithm for the percentage bar isn't reliable, especially if the battery has discharged itself. However, I believe the P4 battery meter is more reliable than P3, it's more conservative, which is why we don't get the advertised 28 min P4 flight time, IMHO.