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Battery drop from 90% to 0% - drone landed in water
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1986 55 10-14 01:32
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CptnBlackBeard
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Hi,

I just had a totaly wierd experience with my Mavic Air.
My drone reported 90% battery and in 1sec battery dropped from 90% to 0% and the drone landed in water.
There was no chance for me to reach it in time to be able to catch it, and the depth and current there is really strong so there was no chance of recovery either.

I took of normaly had flow for 1min:31sec, whent it happened.
Here is the link to the moment where it drops from 90% to 0% in 1sec.


Here is the whole flight video:



Info:
Mavic Air was inspected before flight and all props and everything else was good to go.
No compass errors, nothing. All was good.

Battery was at about 30% (as usual as I store them when I dont plan to fly), I charged all 3 batteries (including the one with which it landed in water); to 100% with my DJI charger about 1h before flight.
This particular battery was used (charged about 30 times in total before);
First flight yesterday, was done normaly recorded some nice footage. Landed back at about 25% which is what I usually land at. My minimum I think is set to 15% not 10%.
Second flight (the one that landed in water) started as normal, battery clicked in (I double checked), battery was not bulged.
(no errors, all good to go)
Took off normaly, stayed a bit close to the shore line for a bit, switched between sport and P mode, everything was ok, proceeded to go further towards the middle of the river.
No errors until 1:29 when I get battery criticaly low, but still shows 90% then on 1:30 drops to 0%, drone kept flighing which was strange, reported that it will land, but was still flying towards the land, but culd not reach it. What puzzlez me is that from 1.30 to 2.06 when the drone landed in water, flight seemd normal but just slowly landing. When it landed on water camera was still working.

Here are the links from AirData:
https://app.airdata.com/flight/5989bf8a865f5b54a94c0e4f64313f93/GENERALNotifications&val=detailed

I've seen a couple of more videos on youtube with similar bug showing, one of the guys in the video lands on a frozen lake.
10-14 01:32
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CptnBlackBeard
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Here is the link to the video I also found on youtube:

10-14 01:33
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CptnBlackBeard
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Just to add, here you can see the temperature for that day. 13.10.19.

Weather

Weather

10-14 01:51
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Vofas
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Hi! Was the battery firmware updated to the latest?
10-14 04:05
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BobB
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CptnBlackBeard Posted at 10-14 01:51
Just to add, here you can see the temperature for that day. 13.10.19.[view_image]

Did you get it fished out of the water? or is it still in the drink?
10-14 04:14
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CptnBlackBeard
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Vofas Posted at 10-14 04:05
Hi! Was the battery firmware updated to the latest?

Hi,
Yes.
Battery and drone were on latest firmware.
There was no request for update that day at home, nor at the flight location.
10-14 04:30
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CptnBlackBeard
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BobB Posted at 10-14 04:14
Did you get it fished out of the water? or is it still in the drink?

Hi,
It was not possible to get the drone out.
It is a fast moving river water and the Air landed pretty far from shore.
10-14 04:31
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SD_Pilot
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In your #1 post wow that was insane. I was anxious just watching that battery drop so quickly like that. There def seems to be some kind of serious SW stuff going on if in fact that's the root cause.

Two things I observed that for me would have done differently - the craft took off way to quickly upon start without locking in HP. Also, I constantly keep an eye glued on the battery %. Once I would've seen the % dropped the way it did even before it got to 0% I would've turned the craft towards the HP. Take a close look at how the % drops way too fast that would've caused concern.
10-14 05:25
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DAFlys
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Upload your flight log here - https://www.phantomhelp.com/LogViewer/Upload/ It might show some better details of what happened.
10-14 05:40
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CptnBlackBeard
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SD_Pilot Posted at 10-14 05:25
In your #1 post wow that was insane. I was anxious just watching that battery drop so quickly like that. There def seems to be some kind of serious SW stuff going on if in fact that's the root cause.

Two things I observed that for me would have done differently - the craft took off way to quickly upon start without locking in HP. Also, I constantly keep an eye glued on the battery %. Once I would've seen the % dropped the way it did even before it got to 0% I would've turned the craft towards the HP. Take a close look at how the % drops way too fast that would've caused concern.

I took of in P mode, then switched to sport to test, then back to P;
Maybe that is what you see when you look at battery dropping.
Later on for the sprint towards the middle, I was also in sport, so at the time I thought maybe that is the reason for faster drop.
For me it did not catch the eye, since I was in sport mode, but now when I look at it, second time, I'm not sure what to think.
But the problem is 90 to 0 in 1sec
10-14 06:26
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CptnBlackBeard
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DAFlys Posted at 10-14 05:40
Upload your flight log here - https://www.phantomhelp.com/LogViewer/Upload/ It might show some better details of what happened.

I'm in the office now, I'll try to do it when I get back home.
10-14 06:31
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RGMGFitness
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Sorry about the loss.  Yeah, I've heard of similar experiences from other users as well.  Knock on wood, I've not experienced this issue myself but I know DIJ should be familiar with this issue.  If you search around the DJI forums and YouTube you'll see others who have reported something similar.  

Yeah, once it hits the water it's kind of 'game over'.  
10-14 06:38
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CptnBlackBeard
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RGMGFitness Posted at 10-14 06:38
Sorry about the loss.  Yeah, I've heard of similar experiences from other users as well.  Knock on wood, I've not experienced this issue myself but I know DIJ should be familiar with this issue.  If you search around the DJI forums and YouTube you'll see others who have reported something similar.  

Yeah, once it hits the water it's kind of 'game over'.

Hi,

Have you heard of any solution, reimbursement, new/refurbished device,  from the DJI side about this?

With a quick search on youtube I've found the guy with the same problem and the video.
Also quick search on google shows mutiple occurences of the same issue happening.
I really love DJI and my Mavic Air, lots of nice moments and lots of memories captured with it.

10-14 06:47
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CptnBlackBeard
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DAFlys Posted at 10-14 05:40
Upload your flight log here - https://www.phantomhelp.com/LogViewer/Upload/ It might show some better details of what happened.

Hi,

I managed to get my phone connected.
Here is the flight log.
https://www.phantomhelp.com/LogViewer/W485TXGRRF1VSM0IDCP9

DJIFlightRecord_2019-10-13_[13-36-12].txt.zip

295.98 KB, Down times: 4

Fligh Log

10-14 06:50
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RGMGFitness
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CptnBlackBeard Posted at 10-14 06:47
Hi,

Have you heard of any solution, reimbursement, new/refurbished device,  from the DJI side about this?

Yes, if the fault is within the drone/software there is a good chance DJI will work with you on a reimbursement of some type.  Just upload the logs (as it appears your doing later) and I think you'll be okay.

Either way, keep us posted in the forum as I would love to know myself how this all turns out for you.  Again, I know your not the 1st to experience this issue.
10-14 06:54
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CptnBlackBeard
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CptnBlackBeard Posted at 10-14 06:50
Hi,

I managed to get my phone connected.

Shows the same.
You can see the battery cell 3 in red, but no warning until 1.29.6 s1.29.6 90%
1.29.7 0%
Less then a second!

10-14 06:54
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JJB*
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Hiya,

Had a look at your flightlog data, sorry for your loss.
At 1m20 a batt error in the log ; "BattTempVoltageLow", cell 3 starts to drop his voltage.
At 1m27 cell3 drops to 2.581 Volts, total cells 9.5 volts.
Errror "Critically Low Voltage Warning.Aircraft Landing", MA starts his forced landing.

Looks like a batt 'fail' due to cold temperature. But in the log is written the temp of the battery, started at 26 degree, high value 39 degree.

Hope that DJI will help you!

cheers
JJB
analysis1.png
10-14 06:56
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SD_Pilot
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Makes sense ^^
10-14 06:58
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CptnBlackBeard
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JJB* Posted at 10-14 06:56
Hiya,

Had a look at your flightlog data, sorry for your loss.

Thanks.
It was a warm day. Not too hot even.
I put the weather forecast up there just for that reason.
10-14 06:58
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Ben Mason
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I don't think i need to look at the log file i can see it in your original post, if your drone is in warranty you should make a virtual case with DJI and send them the flight logs, if the battery had immediately died DJI would have most likely only given you a 15% discount on a replacement drone, but yours actually shows 90% to 0%, no clue why they would reject your warranty claim in this case. If your item is no longer in warranty then i feel for you, it sucks to loose a drone to a fault like this.
10-14 07:00
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CptnBlackBeard
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Ben Mason Posted at 10-14 07:00
I don't think i need to look at the log file i can see it in your original post, if your drone is in warranty you should make a virtual case with DJI and send them the flight logs, if the battery had immediately died DJI would have most likely only given you a 15% discount on a replacement drone, but yours actually shows 90% to 0%, no clue why they would reject your warranty claim in this case. If your item is no longer in warranty then i feel for you, it sucks to loose a drone to a fault like this.

You, mean a product fault / bug in production ?

Here are more exmples of the same issue:

https://mavicpilots.com/threads/ ... t-lost-my-ma.37910/

https://forum.dji.com/forum.php?mod=viewthread&tid=141380
https://mavicpilots.com/threads/battery-failure-mid-flight.37990/
10-14 07:17
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CptnBlackBeard
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There's even more as I dig deeper.

https://forum.dji.com/forum.php?mod=viewthread&tid=141637

I'm at work but this is just the first couple of links down, and there are already 4 more threads with the same bug showing.

10-14 07:23
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CptnBlackBeard
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It's crazy how often this happens, there is definitely something wrong in the design.
Screen Shot 2019-10-14 at 17.29.37.png
10-14 07:32
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Ben Mason
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CptnBlackBeard Posted at 10-14 07:17
You, mean a product fault / bug in production ?

Here are more exmples of the same issue:

Well it certainly looks like a manufacturer fault, but i wouldn't call it a problem with every battery, don't forget DJI probably manufacturers hundreds of thousands of these batteries, so what you can see as a wide spread problem with 10s of cases is actually a very tiny fraction of the whole. If a product is really suffering from a large scale series of faults it is pulled from shelves.
10-14 07:53
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HereForTheBeer
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this is one reason i got rid of my mavic air.. i had a handful of batteries, lost count how many overtime i ended up with total but i have 3 broken batteries laying that got roasted from my mavic air.

mavic air's battery is desperately undersized or underspeced for the drone its forced to fly with.. either need 4 cell packs or they need to up the quality of these cells.  like no lead time between a battery warning you something is wrong and it taking a sh*t.  i been there done that , luckily never in a river but i had to make a few emergency landing nd then go race over to the drone, hop itse still there and grab it . now its part of my overall instinct flying any drone thanks to my mavic air close calls.   im on the lookout for emergency landing spots as im flying so i can put the drone down safely if sh*t hits the fan.   
10-14 08:30
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CptnBlackBeard
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Ben Mason Posted at 10-14 07:53
Well it certainly looks like a manufacturer fault, but i wouldn't call it a problem with every battery, don't forget DJI probably manufacturers hundreds of thousands of these batteries, so what you can see as a wide spread problem with 10s of cases is actually a very tiny fraction of the whole. If a product is really suffering from a large scale series of faults it is pulled from shelves.

What if it's not the battery but the controller.
Most of the reports have similarities, sport mode on, fly for some time, one of the cells dip and the controller starts to land, you can even see it on the other reports where the battery dipped and then recovered but the drone continued to land none the less.
10-14 08:39
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Blizzard
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With one battery of my Mavic Pro, It refuse to take off automatically.
It showed me that there was a difference between the 3 cells.
The 3° cell was 0,15V lower than the other ones.
I could however, start manually and let it hover for 13 minutes.
After that I could recharge the battery and fly normally.

So I think the difference in voltage from the 3° cell initiated the forced landing.

10-14 08:39
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CptnBlackBeard
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Blizzard Posted at 10-14 08:39
With one battery of my Mavic Pro, It refuse to take off automatically.
It showed me that there was a difference between the 3 cells.
The 3° cell was 0,15V lower than the other ones.

yes, that is probably true.
the problem is that it did not report anything prior the drop to zero.

if I had some warning, any warning that would point that I could of saved the drone, this way I was put in an unrecoverable position, drop from 90% to 0% in less than 1 sec.

10-14 08:42
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DJI Stephen
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Hello and good day Vladimir Kopric. I am sorry to know what happened to your previous flight with your DJI Mavic Air. Since this unfortunate incident happened. I would recommend you to contact our DJI support team at https://www.dji.com/support?site=brandsite&from=nav for further assistance. Our DJI support team would do their best to find out the reason of the incident and then the corresponding resolution would be provided. Again I am sorry and thank for your understanding.
10-14 09:07
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Blizzard
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CptnBlackBeard Posted at 10-14 08:42
yes, that is probably true.
the problem is that it did not report anything prior the drop to zero.

I was lucky it was reported before take off. Maybe, when already in flight, the only warning is that he initiate a forced landing.
10-14 09:21
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DJDudu
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Damn this topic is scary. I just came home after flying mavic air and now I am scared to use it again. I've never had any problem with my batteries, but if it drops to 0% like that I am seriously concerned about my drone.
10-14 09:36
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JJB*
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Blizzard Posted at 10-14 08:39
With one battery of my Mavic Pro, It refuse to take off automatically.
It showed me that there was a difference between the 3 cells.
The 3° cell was 0,15V lower than the other ones.

I think that when the total voltage drops below a certain level, a force landing will be initiated
In this case the moment the total voltage dropped below 10 volts.

Looks like  a low voltage warning when a cell drops below 3 volts, landing when total drops below 10.

But why 0% indicating as the total volts during landing increased again to 11.3 (yeah i know less current draw so voltage goes up), but why a steady ZERO %?  Must be the software wich regulates this to show.

DJI ??

cheers
JJB
10-14 09:45
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Ben Mason
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CptnBlackBeard Posted at 10-14 08:39
What if it's not the battery but the controller.
Most of the reports have similarities, sport mode on, fly for some time, one of the cells dip and the controller starts to land, you can even see it on the other reports where the battery dipped and then recovered but the drone continued to land none the less.

It's highly unlikely that it's the controller. The 2 most likely culprits are either the battery or the battery interface board(FCB). Batteries can do some crazy stuff if there's a fault, give the drone x4 ESC error, Prevent the drone from powering off, Show 0% or N/A even though the battery is fully connected and powered.
I'd bet on the battery, still your one unlucky guy to get it during flight.
10-14 23:16
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Blizzard
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I think it's a pity that DJI doesn't sell a charger where you can't balance the 3 cells of the battery yourself. And where you can visualize that on a screen, you would discover in time that one cell is no longer balanced with the others.
10-14 23:51
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*DM*
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DJDudu Posted at 10-14 09:36
Damn this topic is scary. I just came home after flying mavic air and now I am scared to use it again. I've never had any problem with my batteries, but if it drops to 0% like that I am seriously concerned about my drone.

Thats a bit like worrying about an impending meteor impact.

Well, almost
10-15 00:06
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CptnBlackBeard
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Ben Mason Posted at 10-14 23:16
It's highly unlikely that it's the controller. The 2 most likely culprits are either the battery or the battery interface board(FCB). Batteries can do some crazy stuff if there's a fault, give the drone x4 ESC error, Prevent the drone from powering off, Show 0% or N/A even though the battery is fully connected and powered.
I'd bet on the battery, still your one unlucky guy to get it during flight.

Sorry, I wasn't clear. I meant the voltage or current controller (not the controller in hand)  that should handle these things.
Just like you put a condenser to act as a buffer if the drop happens, etc.
So yeah, it might be the battery controller or the unit that reads the data from the battery controller.
Additional problem is that SW is not reporting any of this until it is too late.
10-15 00:27
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Archangel3356
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That’s a pretty frightening video to look at. I have 2 phantom batteries where one cell is off on both and after trying the discharge/recharge regiment, which didn’t work, I guess it’s time to dispose of them. Sorry for your loss blackbeard, hope it’s made right somehow.
10-15 06:36
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CptnBlackBeard
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So I just got back from DJI support.

And basically they are asking me to pay them (to do their job)  to analyze the data from the crash in order to solve the bug so it doesn't happen to anyone else, but they will not compensate me for the crash????
WTF?
Just WTF?

Here is the screen shot.

10-17 09:30
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Bing Err
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oh man. That sucks. I had 2 batteries go bad on my Mavic Air. 1 was replaced since it was within 6 months, but the other was out of warranty so I don't use that one anymore. They would drop in % just like yours. Once the MA landed in the street and once it was in a field. So glad it never landed in a lake or pond. It even made me stop flying my Mavic Air for months because I was scared where it was going to land, but after I figured out that only 2 of my 5 batteries were guilty of that behavior I started flying again and haven't had issues since. Sorry you lost your bird. That is a shame
10-17 10:04
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CptnBlackBeard
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Bing Err Posted at 10-17 10:04
oh man. That sucks. I had 2 batteries go bad on my Mavic Air. 1 was replaced since it was within 6 months, but the other was out of warranty so I don't use that one anymore. They would drop in % just like yours. Once the MA landed in the street and once it was in a field. So glad it never landed in a lake or pond. It even made me stop flying my Mavic Air for months because I was scared where it was going to land, but after I figured out that only 2 of my 5 batteries were guilty of that behavior I started flying again and haven't had issues since. Sorry you lost your bird. That is a shame

I would have understood if they said something along the lines of hey, you are out of warranty and your battery might have been faulty from before, but our fault is that our SW is not reporting cell difference before the flight, nor at all until the cell dies.
Would you please allow us to analyze the data to try and fix this for the others, here's a 50usd towards your new DJI drone and a big thank you for helping us fix this.
50 USD is nothing towards a 1000usd drone but shows goodwill.

But asking me to pay them to fix their ... is just plain insane.

I own business also and if someone comes with a bug / missing crucial feature in our app even after their subscription is over, I give them free subscription until the bug is fixed (usually couple of months after that also) and let them decide if they want to renew after that. Also a nice thank you and we respect your feedback email is sent out also.

I dont ask them to pay me to fix my bug!
10-17 10:32
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