The other day I was flying my DJI Mavic Mini in an open field.  There was no wind and the weather was good.  I few the drown out about a few hundred meters when I could see that it was losing altitude.  Inputs on the joystick to go up had no effect as the drone simply landed. After the drone landed I examined the props which appeared to be 100% normal.  I changed the battery even though the flight time was under 3 total minutes in length. This time I few the drone directly in front of me as I returned to my original launch location. After a few minutes, the same thing happened again.  As the drone touched down the props keep spinning and you could take off again only to have it land on its own a few seconds later even with full-up inputs to the joystick. This happened more than a half dozen times until I just packed up and went home.  I examined the logs when I returned home and the logs showed a message that the propeller was rotating too fast about 30 seconds into the 3 min flight. Like I said the drone props look fine, with no warping, cracks, or even scratches.  I have lost confidence in its ability to fly anywhere except within a few feet to me.  Frankly, a similar incident happened a few months back several subsequent flights were just fine so I assumed that it was just a glitch.  

Try uploading your log (.txt) file to airdata.com and maybe it will tell us more about the anomaly. Also check to make sure you are not in a restricted zone. Might want to post the .dat file here (inside a zip file).

Sometimes the propellers can cause the behavior you are describing. Here is some information on the subject :https://forum.dji.com/forum.php? ... D712%26typeid%3D712

The Mini was plagued by uncommanded descents early in its life but this was largely fixed with firmware 1.0.5.
Check your firmware version and if it's earlier than 1.0.5, update it.
Also, replacing your propeller blades would probably be a good idea.

Hi,

I had the same experience with my Mini1, even on the latest firmware.
Not only did the Mini1 suffered from rear deformed blades but also from a height failure in the 'system'.

DJI did replaced my mini1 for a new one. Probably is this height error written in the DAT file.

So my advice, contact DJI support for this.

cheers
JJB

GaryDoug Posted at 4-3 14:50
Try uploading your log (.txt) file to airdata.com and maybe it will tell us more about the anomaly. Also check to make sure you are not in a restricted zone. Might want to post the .dat file here (inside a zip file).

Doug, Thanks for the reply.  While I can see the log on my android phone I do not know how I can save it as t txt file so I can send it to you.

steveimke Posted at 4-4 11:44
Doug, Thanks for the reply.  While I can see the log on my android phone I do not know how I can save it as t txt file so I can send it to you.

The .txt file by date is on your device in the DJI/dji.go.v5/FlightRecord folder. You can create a free account at airdata.com and upload that file there. The .dat file is in the MCDatflightRecords folder under the above. That is the file you can zip and attach here.

I had this happen to me; it turned out to be the props.... Jump in to 45 seconds on this video:

Like Ian has shown on his video a slightly bent rear propeller may cause the uncontrolled descent due to loss of lift. When you fly forward the Mini will have a pitch down attitude and when the rear motors reach the speed limit the ESC will reduce the speed of the front motors to pitch down losing total lift. This will cause the Mini to stall and slowly lose altitude until it hits the ground. I have been told that when the Mini stalls flying forward if you fly backwards it will regain lift because the ESC will lower the speed of the rear motors and  increase the speed of the front motors regaining lift. I haven't tryed my self but you can try if it happens again.

In addition to swapping out the props, I modified my flymore combo case so the bottom props don't get squashed when stored.  I cut the front of the support and pressed it down as well as added some foam for the two rear feet and gimbal cover to lift the Mini up.  No issues since.

Ian in London Posted at 4-4 23:41
I had this happen to me; it turned out to be the props.... Jump in to 45 seconds on this video:
https://youtu.be/ngOuPuRGhLQ?t=47

Awesome.  I'll change out the props.   

amferreira Posted at 4-5 04:15
Like Ian has shown on his video a slightly bent rear propeller may cause the uncontrolled descent due to loss of lift. When you fly forward the Mini will have a pitch down attitude and when the rear motors reach the speed limit the ESC will reduce the speed of the front motors to pitch down losing total lift. This will cause the Mini to stall and slowly lose altitude until it hits the ground. I have been told that when the Mini stalls flying forward if you fly backwards it will regain lift because the ESC will lower the speed of the rear motors and  increase the speed of the front motors regaining lift. I haven't tryed my self but you can try if it happens again.

Good advice and consistent with my experience. Then I fled it backward it flew ok.  Flying forward it dropped. While I can't see any deformation in the props I understand it is how it is stored and that it only takes very little deformation.

Art Vandelay Posted at 4-5 05:19
In addition to swapping out the props, I modified my flymore combo case so the bottom props don't get squashed when stored.  I cut the front of the support and pressed it down as well as added some foam for the two rear feet and gimbal cover to lift the Mini up.  No issues since.

[view_image]

Pretty radicle modification.  There must be a way to orient the props in the case so as not to put pressure on the props.  I wonder how it came when it originally shipped.   

GaryDoug Posted at 4-4 12:01
The .txt file by date is on your device in the DJI/dji.go.v5/FlightRecord folder. You can create a free account at airdata.com and upload that file there. The .dat file is in the MCDatflightRecords folder under the above. That is the file you can zip and attach here.

I did upload the log file to the site you recommend.   There sure is a lot of information there.  Thanks for that advice. I did create a zip file with the log but I can't seem to upload it here.  Anyway, I think it has to be the props. I'll follow the advice of Ian and try to discover which set is bad and replace them.

steveimke Posted at 4-5 08:24
I did upload the log file to the site you recommend.   There sure is a lot of information there.  Thanks for that advice. I did create a zip file with the log but I can't seem to upload it here.  Anyway, I think it has to be the props. I'll follow the advice of Ian and try to discover which set is bad and replace them.

The .dat file will tell you which motor has the problem. If you can't post it in a zip file here, maybe put it on some free file hosting site (file.io., mediafire, etc...)and post the link to it here.

steveimke Posted at 4-5 08:21
Pretty radicle modification.  There must be a way to orient the props in the case so as not to put pressure on the props.  I wonder how it came when it originally shipped.

Actually I'm afraid that it's been widely commented on how the case causes this slight but critical deformation.  You may try leaving the case upright so the handle is up in the air but others think leaving it out of the box comepltely is the safest method, only using the case for when yo'ure travelling.

Cheers
Ian

Ian in London Posted at 4-5 11:54
Actually I'm afraid that it's been widely commented on how the case causes this slight but critical deformation.  You may try leaving the case upright so the handle is up in the air but others think leaving it out of the box comepltely is the safest method, only using the case for when yo'ure travelling.

Cheers

Ian, That was my plan to leave it out on a shelf and only place it in the case to transport.  Your video was very informative.  Thank you so much!!!

GaryDoug Posted at 4-5 10:22
The .dat file will tell you which motor has the problem. If you can't post it in a zip file here, maybe put it on some free file hosting site (file.io., mediafire, etc...)and post the link to it here.

I think I figured out how to upload the zip of the log. It should be attached here. I'd love to learn how to tell which motor/prop from the log.

steveimke Posted at 4-5 13:47
I think I figured out how to upload the zip of the log. It should be attached here. I'd love to learn how to tell which motor/prop from the log.

Wrong file for the motors info. We need the ".dat" file. See post#7.

GaryDoug Posted at 4-4 12:01
The .txt file by date is on your device in the DJI/dji.go.v5/FlightRecord folder. You can create a free account at airdata.com and upload that file there. The .dat file is in the MCDatflightRecords folder under the above. That is the file you can zip and attach here.

That directory is empty.

steveimke Posted at 4-5 14:15
That directory is empty.

Do you have your file sync to DJI turned on? That usually erases those files

I di have auto-sync flight records checks in setup.  Should I not have this selected?  Also, I do have the alrdata app on my phone and PC and sync there too.

steveimke Posted at 4-5 14:28
I di have auto-sync flight records checks in setup.  Should I not have this selected?  Also, I do have the alrdata app on my phone and PC and sync there too.

It's personal preference. I never have it on because I only use a dedicated device.

Retrieving the deleted files is possible but usually requires some complex operations on your phone that is not worth the risk. I suggest turning off the sync and fly again

GaryDoug Posted at 4-5 14:32
It's personal preference. I never have it on because I only use a dedicated device.

Retrieving the deleted files is possible but usually requires some complex operations on your phone that is not worth the risk. I suggest turning off the sync and fly again

Noted.  I do have the ability to see all the files on my phone using an app called Astro File Mananger.  I was able to navigate to that directory manually but it was empty because apparently it was synced somewhere.  Do you know where the file goes?

That said,  My son who was with me indicated that to his recollection the left rear prop was quivering. when we located the drone after the first auto-landing.  So in the absence of the proper .dat I think I'll just replace those 2 blades and see if the issue goes away.  BTW I have unchecked the auto-sync in the DJI FLy app since I use have a single device that I use.

Art Vandelay Posted at 4-5 05:19
In addition to swapping out the props, I modified my flymore combo case so the bottom props don't get squashed when stored.  I cut the front of the support and pressed it down as well as added some foam for the two rear feet and gimbal cover to lift the Mini up.  No issues since.

[view_image]

I did run across this image from the DJI Support form that you how to place your props before placing them in the case. shows  

steveimke Posted at 4-5 14:40
Noted.  I do have the ability to see all the files on my phone using an app called Astro File Mananger.  I was able to navigate to that directory manually but it was empty because apparently it was synced somewhere.  Do you know where the file goes?

That said,  My son who was with me indicated that to his recollection the left rear prop was quivering. when we located the drone after the first auto-landing.  So in the absence of the proper .dat I think I'll just replace those 2 blades and see if the issue goes away.  BTW I have unchecked the auto-sync in the DJI FLy app since I use have a single device that I use.

The shaking prop is a good indication. That's the way the drone tells you which one to examine.

GaryDoug Posted at 4-5 13:59
Wrong file for the motors info. We need the ".dat" file. See post#7.

I agree,  and not all unwanted descents are due to blades failures....

My mini1 had good blades and dropped down the sky....