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P3p entered landing mode on its own.

Discussion in 'Pro/Adv Discussion' started by SeabrookBill, Mar 2, 2016.

  1. SeabrookBill

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    I was flying my P3p using Litchi way stations when all of a sudden the plane started to auto land. I was in f mode at the time so switched to p mode and stopped the descent and was able to fly the 500 feet back to me. Battery was freshly charged that day and I was on my second short flight when this happened. To my untrained eye, the log was fine. It was a bit gusty that day. My firmwares are current and the battery has been charged 27 times. I use a galaxy s6. My hands were not on the controls as I was watching the GS in action. The RC was chiming at the same time and I think it was chiming to let me know about the landing. In the Litchi log, line 1118 the mode switches from navi to landing at about 62 percent battery. The P3p would have landed in a river, had she continued. Any insight as to why this was happening is greatly appreciated.
     
  2. ryantrax

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    Did you upload your log to healthydrones.com ? Were there any geofences in your flight area? I'd be interested to know what happened as I use Litchi pretty regularly too and haven't encountered this issue yet...knock on wood.
     
  3. SeabrookBill

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  4. ryantrax

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    I don't see your log.
     
  5. SeabrookBill

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    I tried to upload the CSV file, but apparently this forum does not accept csv files. Here it is as a .txt file using tabs as a delimiter. Excel will have no issue reading this
     

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  6. ryantrax

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    Everything looks kosher as far as hardware goes. Did you save your POI's in Litchi? It looks like you were navigating at the time it happened, maybe your last point was a little wacky? You were technically in a no-fly zone there because of the MUSC hospital heli-port but you were in it when you took-off too. That is just a category C heli-port so I don't think geofencing would come into play there.
     
  7. SeabrookBill

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    I did save the POI in Litchi, but after the P3P descended to about 38 feet I switched out of F mode and took the P3P back up and flew it from then on. I flew for another several minutes and had no more issues.
     
  8. Mark The Droner

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    "On your second short flight..."

    This is the same battery?
     
  9. John Locke

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    It would be good to load your .txt into msinger's flight log reader and take a look at the voltages at the time it triggered auto land. I'm finding that your 62% can vary greatly in voltage, from one battery and craft to another, especially if you land at 85%, turn off the battery, turn it back on and fly on the same battery again. That's a no no, even though it would seem to be perfectly acceptable. The percentage in the gas gauge is whacky IMO. I believe the auto landing defaults to a certain voltage, not percent, and everybody watches the percent bar because that's the default method. Make sure to enable the VOLTS to display in the upper right corner under the Percent level. Start coming back for landing around 3.6V (lowest voltage of the 4 cells will display). Of all the issues with P3, I worry more about the whacky battery issues more than anything. Even with 1.6 firmware I see inconsistencies in the battery voltage versus percentage, it makes no sense, so I don't think the firmware algorithm is fixed, 100%.
     
  10. SeabrookBill

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    Yes same battery, but I landed and didn't even shut down. I've done this before, but it now seems like its almost a must to change the battery even when doing short (2-3 minute) flights.
     
  11. SeabrookBill

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    Thanks John, I am getting the idea, that the intelligent battery needs to be handled intelligently. That must be why it's called an intelligent battery.
     
  12. Mark The Droner

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    What about temp? How cold was it outside?
     
  13. SeabrookBill

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    It was mid 50's F but the wind was gusting a bit to maybe 20 MPH. I was flying with just a long sleeve shirt on, so not too cold. ome of my ideas is that the P3P had to fight some wind to stay on course and that created some sort of power spike which put the P3P in landing mode.
     
  14. Mark The Droner

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    Okay - there's a bit of a risk flying with a battery whose temp is under 20 C (68 F). And it's even worse with a battery that's under 15 C (59 F). It's been discussed in several threads. The problem has sometimes been called "internal resistance" and sometimes called "voltage lag." But it's the same problem. While your battery's voltage will normally drop under load, the drop is significantly more if the battery is cold as defined above. And if an individual cell drops too far, you'll get a critical battery warning and the auto-landing. So that may have been what happened. Normally this problem solves itself when you have a fully charged battery because the voltage is high enough that a voltage lag isn't enough to give you a problem. And as you fly, the battery is warming itself up. But to take a partially discharged battery that's been allowed to cool and install it into an aircraft cold - that is inviting trouble. So that may be the explanation.
     
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  15. SeabrookBill

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    I believe your assessment is what happened. I will be careful to ensure that I only use fully charged batteries and that they are at least 20 C. Thank you for such a complete assessment.
     
  16. DroneDaddy

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    This same thing just happened to me. I used a 60% discharged battery that was cool. I started a mission, flew around, then at about 50% it started to auto land. I couldn't get it to stop either but had enough altitude to just make it back. Temp outside was 55F.

    Lesson learned. Use full batteries.