Get more from your Mavic
The largest Mavic community in the world
Join Us Now

I messed up...

Hefner413

Member
Joined
Nov 8, 2017
Messages
7
Reactions
7
Age
40
So I landed my mavic on top of a structure that I could not access by foot (dumb idea #1). The prop was up against a rod, obstructing my ability to take off. My plan (dumb idea #2)... since I had no way to access my drone and I did not want to just leave it... I decided to buy a second mavic to retrieve the first... yeah, I know, bu bear with me. So I made a 3 foot wire hook and flew up and caught hold of the mavic well and was flying it toward me. It was going ok, but it was going slow and I dropped it a couple times during the attempt and had to pick it back up a few times. I received a warning of "Battery: Over current during discharge," but otherwise, no issues. I was getting low on battery, so aborted the attempt and began to descend at about 16% battery from 60 feet. I was descending straight down and halfway, the drone seemed to become unresponsive and flew straight into the concrete and hit very very hard. I reviewed the flight log and the battery rapidly discharged from 16% during descent. It reported that it was auto landing, but that was the only error message. I had reversed the throttle prior to crash, but no response. The battery read 4% after the crash. I've flown DJI for years and have done various dumb things like this, but have never had a DJI crash while landing like this. Any thoughts?
 
  • Like
Reactions: wisesafe

MavicCF

Well-Known Member
Joined
Mar 20, 2017
Messages
1,087
Reactions
606
Age
19
Location
Colorado
So I landed my mavic on top of a structure that I could not access by foot (dumb idea #1). The prop was up against a rod, obstructing my ability to take off. My plan (dumb idea #2)... since I had no way to access my drone and I did not want to just leave it... I decided to buy a second mavic to retrieve the first... yeah, I know, bu bear with me. So I made a 3 foot wire hook and flew up and caught hold of the mavic well and was flying it toward me. It was going ok, but it was going slow and I dropped it a couple times during the attempt and had to pick it back up a few times. I received a warning of "Battery: Over current during discharge," but otherwise, no issues. I was getting low on battery, so aborted the attempt and began to descend at about 16% battery from 60 feet. I was descending straight down and halfway, the drone seemed to become unresponsive and flew straight into the concrete and hit very very hard. I reviewed the flight log and the battery rapidly discharged from 16% during descent. It reported that it was auto landing, but that was the only error message. I had reversed the throttle prior to crash, but no response. The battery read 4% after the crash. I've flown DJI for years and have done various dumb things like this, but have never had a DJI crash while landing like this. Any thoughts?
To be able to say anything with surety, we'd have to see the flight logs.
 

Hefner413

Member
Joined
Nov 8, 2017
Messages
7
Reactions
7
Age
40
Did you disable the downward facing sensors when you mounted something below the drone?
I thought that also, but the more I thought about it - the mavic still should have been able to respond to my upward thrust despite the downward sensors.
 

Scarnag

Active Member
Joined
May 16, 2018
Messages
43
Reactions
14
****, that sucks. One of the more interesting accounts I read lately though. Sounds like the weight required more current than the battery could provide for any amount of time.
 

Hefner413

Member
Joined
Nov 8, 2017
Messages
7
Reactions
7
Age
40
To be able to say anything with surety, we'd have to see the flight logs.
I'm sorry if I'm uploading the file in the wrong format. Thanks in advance for any help!!
 

Attachments

  • DJIFlightRecord_2018-05-27_[18-12-39].txt
    505.3 KB · Views: 28

Hefner413

Member
Joined
Nov 8, 2017
Messages
7
Reactions
7
Age
40
6m27 is where I begin descending at around 99ft and 16% battery. It hit the ground at 6m35 and 4% battery. So maybe about 8 seconds total.
 

Keule

CTO at SDS
Premium Pilot
Joined
Feb 22, 2017
Messages
2,101
Reactions
1,303
Location
48°18'25"N 11°52'10"E
Site
skydrone-systems.com
@Hefner413, did you begin your rescue flight with 60% battery? Did you ever charge that battery fully?
If not, SmartBattery might not calculate the % correct.

According to the logs, you took off with 60% Battery - Cell#1 = 3.8v, Cell#2 = 3.79v, Cell#3 = 3.8v
Everything looks normal, but at T=137s, the batteries reached 3.5v each, the remaining percentage was 50.
This is not correct, at 3.5v (each cell) it should indicate something below 30%

But the flight continues until T=335s, where the individual cell voltage drops steady until T=380s all cells reached around 3.0v. At that point the aircraft should have never been in the air anymore.
Also the SmartBattery algorithm should have warned you before with a pop-up message and later on activated forced landing.

At T=396s the log ends with battery voltages of Cell#1=1.71v, Cell#2=1.39v, Cell#3=1.85v

Something is wrong with that battery. Either you did not charge that one fully, or the battery is/was faulty from the beginning.
 

tcope

Well-Known Member
Joined
Oct 24, 2016
Messages
2,503
Reactions
1,731
Age
54
Location
Sandy, UT
Many issues with the second flight...

As mentioned, you started to fly at 60% battery. You were not at 60 feet at 16%, you were at 10% at 100 feet. At this point the Mavic will only descend and you can only slow it down. As you were descending, the battery was about to turn off. It is probably a good thing that the Mavic descended as quickly as possible and actually landed otherwise the battery would have turned off mid0flight.

I see no issues with the way that the Mavic behaved.
 

Keule

CTO at SDS
Premium Pilot
Joined
Feb 22, 2017
Messages
2,101
Reactions
1,303
Location
48°18'25"N 11°52'10"E
Site
skydrone-systems.com
So, with the cells < 3V, wouldn't that be damaging the batteries?
Yep, that battery went to the happy hunting grounds.
 

InvisibleName

Well-Known Member
Joined
Feb 5, 2018
Messages
1,943
Reactions
1,260
Age
63
Location
Peterborough, UK
So I landed my mavic on top of a structure that I could not access by foot (dumb idea #1). The prop was up against a rod, obstructing my ability to take off. My plan (dumb idea #2)... since I had no way to access my drone and I did not want to just leave it... I decided to buy a second mavic to retrieve the first... yeah, I know, bu bear with me. So I made a 3 foot wire hook and flew up and caught hold of the mavic well and was flying it toward me. It was going ok, but it was going slow and I dropped it a couple times during the attempt and had to pick it back up a few times. I received a warning of "Battery: Over current during discharge," but otherwise, no issues. I was getting low on battery, so aborted the attempt and began to descend at about 16% battery from 60 feet. I was descending straight down and halfway, the drone seemed to become unresponsive and flew straight into the concrete and hit very very hard. I reviewed the flight log and the battery rapidly discharged from 16% during descent. It reported that it was auto landing, but that was the only error message. I had reversed the throttle prior to crash, but no response. The battery read 4% after the crash. I've flown DJI for years and have done various dumb things like this, but have never had a DJI crash while landing like this. Any thoughts?
I'm impressed that you're prepared to go public with this!!!! :p;)
 

FlyGuy8675309

Well-Known Member
Joined
Jul 7, 2017
Messages
869
Reactions
912
Age
51
Probably should have used a Phantom for the rescue op. More power and more places to hook things too -- but hindsight is always 20/20. Just out of curiosity, where did you land the first one so you couldn't get it? Top of a tower? Private building?
 

Hefner413

Member
Joined
Nov 8, 2017
Messages
7
Reactions
7
Age
40
Yeah, I only did a partial charge, never thinking about that outcome possibility. Add that to my list of dumb ideas here. Thanks for the input all.
 

InvisibleName

Well-Known Member
Joined
Feb 5, 2018
Messages
1,943
Reactions
1,260
Age
63
Location
Peterborough, UK
Yeah, I only did a partial charge, never thinking about that outcome possibility. Add that to my list of dumb ideas here. Thanks for the input all.
Hey, do me a favour. The next time you’ve got $1000 you want to throw away, send it my way!! :rolleyes::)
 

aokusman

Well-Known Member
Joined
May 1, 2018
Messages
692
Reactions
427
Age
45
Yeah, I only did a partial charge, never thinking about that outcome possibility. Add that to my list of dumb ideas here. Thanks for the input all.

Bummer. But you should treat your flights as if you were actually inside the aircraft. You took a lot of chances.
 
Lycus Tech Mavic Air 2 Case

New Threads

Forum statistics

Threads
104,148
Messages
1,206,290
Members
132,832
Latest member
TH_PA