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Mavic Crash Battery Overcharge

grizzard

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It's a crisp foggy day here in Idaho and I wanted to record the snow accumulation as well as do a Tap Flight. Lift off was normal, switched on Tripod Mode and then a slow rotation to record a 360 degree rotation. After that I ascended to above the trees and set up a Tap flight down the driveway. About 100' of forward motion the Controller started issuing "Battery Overcharge" and flashing red. I stopped the Tap Mode and hit RTH but the Mavic did not respond and started descending from that position. It hesitated as in normal landing sequence at 4' and I pulled the stick down to land immediately and the Mavic started spinning and then dropped like a rock from it's 4' position. It tilted just before plummeting into an icy driveway knocking off one of the leg extensions and breaking off one of the props. On close inspection of the propellers it appears that prop icing may have cause a loss of lift and the software's attempt to increase the motor speed was not enough to keep it airborne. Being a pilot this sounds reasonable. I attempted to find the appropriate logs and find out how to read, or where to send the logs to have them read, but I'm not sure how on that sequence. There may have been indications on the screen I did not notice, like the area being unsuitable for landing, which would be helpful to me so that I can correct my miscalculations.

Here is the recorded video ..... Notice that it actual started to spin a little just before ground contact ... then again after landing.

 
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Are you using a iOS device or Android? depending on the device you grab the logs differently.

Once you have the log you can upload it to:
https://www.phantomhelp.com/LogViewer/Upload/

Then we can analyze it and see what happen.

But remember the Mavic Pro is essentially a flying computer. Water and computers don't work well. So moisture in the drone could cause a short. Most likely there could have been a water issue.
 
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Temp?


Sent from my iPad using Tapatalk
 
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We are more than likely going to need the DAT file from the drone. That one will give us motor speed voltage draw etc. Use the instructions here, then upload the DAT to dropbox and provide the link. How to retrieve a .DAT
 
Are you using a iOS device or Android? depending on the device you grab the logs differently.

Once you have the log you can upload it to:
https://www.phantomhelp.com/LogViewer/Upload/

Then we can analyze it and see what happen.

But remember the Mavic Pro is essentially a flying computer. Water and computers don't work well. So moisture in the drone could cause a short. Most likely there could have been a water issue.
Ok, I was able to upload and then look at the picture and data ... All looked well from the picture and the last indicated a forced landing ....
upload_2017-1-27_18-57-32.png
 
Are you using a iOS device or Android? depending on the device you grab the logs differently.

Once you have the log you can upload it to:
https://www.phantomhelp.com/LogViewer/Upload/

Then we can analyze it and see what happen.

But remember the Mavic Pro is essentially a flying computer. Water and computers don't work well. So moisture in the drone could cause a short. Most likely there could have been a water issue.

Yes .... it is a Galaxy Tab S2
 
Temp?


Sent from my iPad using Tapatalk
Temps were about 24º with fog a misty air .............. Where do I find the display that shows what the sticks were doing at the time of the crash? I have seen YouTube postings where you could actually watch what motion was present throughout your flight.
 
Temps were about 24º with fog a misty air .............. Where do I find the display that shows what the sticks were doing at the time of the crash? I have seen YouTube postings where you could actually watch what motion was present throughout your flight.

On the DJI Go App itself, before you enter the bird, you can choose Flight Record (on IOS it's that 3-bar thing in the upper right).
2017-01-27 20.06.01.png 2017-01-27 20.06.04.png
Find the flight from the flight list at the bottom. Tap it.
2017-01-27 20.06.09.png
On the bottom you'll see an icon that looks like a controller. Tap it.
2017-01-27 20.06.16.png
 
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We are more than likely going to need the DAT file from the drone. That one will give us motor speed voltage draw etc. Use the instructions here, then upload the DAT to dropbox and provide the link. How to retrieve a .DAT

Instructions say I need to run a cable from the Mavic to my computer and run the DJi Assistant 2 to access the dat file. Can't find a download link for that even on DJi's site nor in the Play Store for Android.
 
I flew in feeezing fog last week. -10°c. Fight was 30 seconds, blades had ice on them after landing and inspecting. Won't be flying in freezing fog again. Didn't have any warnings but also didn't fly for long.
 
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We are more than likely going to need the DAT file from the drone. That one will give us motor speed voltage draw etc. Use the instructions here, then upload the DAT to dropbox and provide the link. How to retrieve a .DAT

Ok .... here are the dat files ... not sure which was the exact one so this is all 5 this morning. I'm new to dropbox so hope this works ... if not I'll use my MS Cloud with a link.
Dropbox - Mavic dat Jan 27
 
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Also keep in mind the minimum operating temp in the manual is 32 F. Admittedly many of us have flown in much lower but they might give you grief, if trying to call malfunction.
 
Took a look - holy cow! No wonder it said over discharge... It was drawing over 310 watts / 27 amps out of the battery - You can see in the graph on the bottom left that the motors were having to work a little harder to hover as the flight progressed but even running 4 motors flat out shouldn't draw that much power from the battery. I'm assuming you had some sort of short due to condensation of fog in the motors (didn't think this was possible because the windings should be shielded...) - may also be an internal short. My advice would be to (if it's flyable) wait for a nice day and have it hover ~3 feet from the ground; if it was the fog nothing will happen and you will be free to go, however, if it is an internal short and it has a similar issue you should contact dji immediately for an RMA ticket.

Hope this helps!
 

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Oh wow ... Thanks for looking at that. I will definitely do what you said the first flyable day.

Sent from my Nexus 6P using MavicPilots mobile app
Didn't mention this but I'd advise at least one full battery to hover with! It took a few minutes to happen last time so give it a chance to happen again.. It wouldn't be fun if it fell out of the sky later :/
 
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Ok, I was able to upload and then look at the picture and data ... All looked well from the picture and the last indicated a forced landing ....
View attachment 5152
Took a look - holy cow! No wonder it said over discharge... It was drawing over 310 watts / 27 amps out of the battery - You can see in the graph on the bottom left that the motors were having to work a little harder to hover as the flight progressed but even running 4 motors flat out shouldn't draw that much power from the battery. I'm assuming you had some sort of short due to condensation of fog in the motors (didn't think this was possible because the windings should be shielded...) - may also be an internal short. My advice would be to (if it's flyable) wait for a nice day and have it hover ~3 feet from the ground; if it was the fog nothing will happen and you will be free to go, however, if it is an internal short and it has a similar issue you should contact dji immediately for an RMA ticket.

Hope this helps!
It appears that both front props had trouble. The motorCommanded (PWM) increased to 100% finally causing Cell3 to dip below 3.50 volts. That's probably when the overcharge message came.
upload_2017-1-28_4-42-49.png
upload_2017-1-28_4-43-8.png
upload_2017-1-28_4-43-17.png
 
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