I have been flying DJ I Phantom 3 drones for over seven months. First I started with the Phantom Standard Edition and quickly outgrew that and upgraded to the professional edition. I have become comfortable with flying in both the GPS & ATTI modes. Since I am in information technology and kind of geek, really jumped into drone flying with both feet. I believe I have taken every precaution to fly safely and make sure that my drone is in perfect condition prior to launch.

  

I really like the DJI drones because of how great my last drone worked. I could always count on it to come back, even though I always have a backup plan for manually maneuvering my drone home in the ATTI mode.

  

I took my drone out yesterday to search for sharks off of the Pacific Coast. It was a normal day, light winds and sunshine outside. I launched my drone and was flying 1300 ft. out for roughly 7 minutes of flight time. With no warning, my battery went from 64% and shifted to a minus of around -27%. My drone went into the auto descent mode. There was no low battery warning, yet I tried to hit the RTH and everything else that I have carefully practiced for in advance. I watched both visually and through the FPV as my DJI simply descended into the ocean as was swallowed up by the waves.

  

I am posting this here because I loved my DJI drone and I believe that the DJI drone is a reliable product. I am wondering about the battery itself and why this happened? I always do a pre-flight check and all indications were that the battery was healthy. I never want this to happen to me or anyone else, words cannot even explain how I feel.

  

It sounds to me like the aircraft suffered a catastrophic malfunction. I would suggest you post your flight logs to Phantomhelp so we can see what happened. This sounds like it should also be referred to dJI.

That was a legitimate DJI battery right?  Not an aftermarket?  

http://www.phantomhelp.com/LogViewer/Upload/

site credit:  msinger

After you upload, please post the link here.

Here is what I got from my drone.

## 11:01:52
Satellite positioning off. Fly with Caution.
## 11:02:09
Home Point Recorded
## 11:04:54
Home Point Recorded
## 11:04:56
Return-to-Home Altitude:196FT
## 11:17:01
Critically Low Power. Aircraft Landing

Where was the home point recorded at?   It looks like it happened twice?

Jeffyk Posted at 2017-5-28 16:19
Here is what I got from my drone.

## 11:01:52

Here are my log readings from the moment I received the warning until it landed in the ocean.

12m 7.9s        Auto Landing        19satellites        214.6ft        0.4mph        2,425.2ft        50%        14.737V        3.669V        3.691V        3.699V        3.678V        0.03V        Critically Low Power. Aircraft Landing

13m 43.1s        Auto Landing        20satellites        2.6ft        0mph        2,424.0ft        45%        14.647V        3.634V        3.655V        3.683V        3.675V        0.049V

pasaytenpete Posted at 2017-5-28 16:40
Where was the home point recorded at?   It looks like it happened twice?

Yes the home point was recorded.

Mark The Droner Posted at 2017-5-28 15:56
That was a legitimate DJI battery right?  Not an aftermarket?  

http://www.phantomhelp.com/LogViewer/Upload/

Yes Mark, I only purchased legitimate DJI batteries.

http://forum.dji.com/forum.php?m ... &fromuid=214861

We need to examine it more closely.  Go here http://www.phantomhelp.com/LogViewer/Upload/ and follow the directions, upload your flight record and cut and paste the URL from the address bar and post it here.

Did you take off with a fully charged battery, or had it been sitting around unused or partly used for a while?

endotherm Posted at 2017-5-29 06:57
We need to examine it more closely.  Go here http://www.phantomhelp.com/LogViewer/Upload/ and follow the directions, upload your flight record and cut and paste the URL from the address bar and post it here.

Did you take off with a fully charged battery, or had it been sitting around unused or partly used for a while?

I always go with a fully charged battery. My flight log is in two parts because the DJI app crashed and then restarted.

Here is part one of my flight log Part 1

Here is the 2nd part of my log Part2

Please let me know what you think?

Jeffyk Posted at 2017-5-29 14:29
I always go with a fully charged battery. My flight log is in two parts because the DJI app crashed and then restarted.

Here is part one of my flight log Part 1

Do we know why the flight record is in two parts?

I'm not sure what you are referring to when you say "[the] battery went from 64% and shifted to a minus of around -27%".  The flight record shows a pretty normal flight for the most part without any problems aside from a few short interruptions in telemetry at the end. When it gets to 50% battery you start having problems.  You didn't have an insanely high critical battery level set in the app, did you?  It shows the aircraft descending in autolanding mode.  There is no indication of anything triggering this.  The battery levels seem normal and the depletion rate is normal.  There is no battery failure indicated all the way to the end.   There is also no record of RTH being registered, are you sure you pushed and held the button long enough for it to register?  Did it acknowledge it by flashing the button and beeping?

It does show you countering the descent at random times during the landing, by pushing up on the left stick for short bursts.  This did gain altitude, but you let the stick center and it resumed landing into the ocean.  There was no right stick input at all during this phase of the flight.  What should have happened once you realised it was intent on landing on its own and not registering a RTH was that you proceed to fly it home manually.  Most of the time in autolanding or RTH modes you are still able to override the flight by providing additional commands, like you did with the ascend commands.  You should have turned towards home and proceeded with full forward on the right stick, at the same time using the left stick to climb and maintain altitude until over the beach, were you could land it safely.  It would still be trying to land itself the whole time but you can counter it manually and overcome the automatic flight.

Why it went into autolanding is a mystery, perhaps DJI may know or take responsibility.  Usually when that happens there is a cancel slider that appears on the screen.  Were you able to see that and cancel the descent that way?  I don't know any other way to cancel it.  Even a RTH would be in conflict with an autolanding, and I'm not sure who would win or what the combined result would be.  At least we could confirm the battery was healthy and without fault.

I'm sorry for your loss, maybe next time you would be better educated to save the aircraft.

+1 on all points above.

As stated above, there's nothing in the log at all regarding a sudden percentage change in the battery at 64% as stated in the OP and there's nothing to indicate a sudden voltage drop either - as stated in the thread title.  

The only thing that makes sense to me is the AC was deliberately set by the pilot to auto land at 50%.  And the fact that 50% is a nice round number seems to indicate this too.  

this thing happend to me to. I just got back whit 3%of battery I forsed the drone to stay up..I was lucky!  

endotherm Posted at 2017-5-30 03:29
Do we know why the flight record is in two parts?

I'm not sure what you are referring to when you say "[the] battery went from 64% and shifted to a minus of around -27%".  The flight record shows a pretty normal flight for the most part without any problems aside from a few short interruptions in telemetry at the end. When it gets to 50% battery you start having problems.  You didn't have an insanely high critical battery level set in the app, did you?  It shows the aircraft descending in autolanding mode.  There is no indication of anything triggering this.  The battery levels seem normal and the depletion rate is normal.  There is no battery failure indicated all the way to the end.   There is also no record of RTH being registered, are you sure you pushed and held the button long enough for it to register?  Did it acknowledge it by flashing the button and beeping?

Thank you for your input. I wish I could modify the title of the topic and my initial post. The truth is that what I thought was happening was based upon my memory and  apparently not as accurate as the log files that I uploaded after the initial post. Once I uploaded the log files and viewed what was going on, my situation had a slightly different picture.

I also synchronized my phone to DJI and was able to get another look at what happened.  I will post that video here as well.  What really happened is  that my drone started the auto descent  at 50% and on my phone it looked like a minus number. In reality it was at 50% and in red.  When I watch the video of what happened on my phone, the drone was descending at a very rapid rate and I really wasn't at a high altitude.  I did hit the joystick as you indicated, yet in reality  did not think that it was doing anything. Everything I learned from the manuals that I read stated that  Thank you for your input. I wish I could modify the title of the topic and my initial post. The truth is that what I thought was happening was based upon my memory and  apparently not as accurate as the log files that I uploaded after the initial post. Once I uploaded the log files and viewed what was going on, my situation had a slightly different picture.

I also synchronized my phone to DJI and was able to get another look at what happened.  I will post that video here as well.  What really happened is  that my drone started the auto descent  at 50% and on my phone it looked like a minus number. In reality it was at 50% and in red.  When I watch the video of what happened on my phone, the drone was descending at a very rapid rate and I really wasn't at a high altitude.  I did hit the joystick as you indicated, yet in reality  did not think that it was doing anything. Everything I learned from the manuals that I read. Thank you for your input. I wish I could modify the title of the topic and my initial post. The truth is that what I thought was happening was based upon my memory and  apparently not as accurate as the log files that I uploaded after the initial post. Once I uploaded the log files and viewed what was going on, my situation had a slightly different picture.

I also synchronized my phone to DJI and was able to get another look at what happened.  I will post that video here as well.  What really happened is  that my drone started the auto descent  at 50% and on my phone it looked like a minus number. In reality it was at 50% and in red.  When I watch the video of what happened on my phone, the drone was descending at a very rapid rate and I really wasn't at a high altitude.

I did hit the joystick as you indicated, yet in reality I did not think that it  did not appear to have an effect. The bottom line is that the aircraft never should've gone into that mode at 50% power.

Mark The Droner Posted at 2017-5-30 04:26
+1 on all points above.

As stated above, there's nothing in the log at all regarding a sudden percentage change in the battery at 64% as stated in the OP and there's nothing to indicate a sudden voltage drop either - as stated in the thread title.  

Who in their right mind would deliberately set the critical battery level to 50%? Besides never could've happened since the software only allows you to set it at 30% maximum.

Jeffyk Posted at 2017-5-30 22:23
Who in their right mind would deliberately set the critical battery level to 50%? Besides never could've happened since the software only allows you to set it at 30% maximum.

Did you know in post 15, your first few sentences are written twice?  And then your latter sentences are also written twice?  And then you wrote some of them again a third time?  

There are pilots who have gone to critical battery and autoland over a mile from home and have successfully brought it home by using the up elevator stick.  


Sorry for your loss.  

Mark The Droner Posted at 2017-5-31 02:00
Did you know in post 15, your first few sentences are written twice?  And then your latter sentences are also written twice?  And then you wrote some of them again a third time?  

There are pilots who have gone to critical battery and autoland over a mile from home and have successfully brought it home by using the up elevator stick.  

Yes,  I noticed that this morning. That's what I get for trying to post late at night on my cell phone!

Jeffyk Posted at 2017-5-30 22:21
Thank you for your input. I wish I could modify the title of the topic and my initial post. The truth is that what I thought was happening was based upon my memory and  apparently not as accurate as the log files that I uploaded after the initial post. Once I uploaded the log files and viewed what was going on, my situation had a slightly different picture.

I also synchronized my phone to DJI and was able to get another look at what happened.  I will post that video here as well.  What really happened is  that my drone started the auto descent  at 50% and on my phone it looked like a minus number. In reality it was at 50% and in red.  When I watch the video of what happened on my phone, the drone was descending at a very rapid rate and I really wasn't at a high altitude.  I did hit the joystick as you indicated, yet in reality  did not think that it was doing anything. Everything I learned from the manuals that I read stated that  Thank you for your input. I wish I could modify the title of the topic and my initial post. The truth is that what I thought was happening was based upon my memory and  apparently not as accurate as the log files that I uploaded after the initial post. Once I uploaded the log files and viewed what was going on, my situation had a slightly different picture.

Could you clarify whether you had Smart RTH enabled? Have you gotten in contact with Support about this as well in order to have the flight logs evaluated?

I am really not sure. What I am sure of is that my Drone started auto landing when the battery level hit 50% and it lowered into the Pacific Ocean. If it had not malfunctioned I would still have my drone today. A couple of peeps here have analyzed my logs and the battery was in good condition and fully charged. I am told that I might have been able to make it home, yet I am not so certain about that because I took off above sea level. When I hit the stick up I did not seem to get lift. I have not opened a case with DJI yet, but I will.

Jeffyk Posted at 2017-5-31 17:16
I am really not sure. What I am sure of is that my Drone started auto landing when the battery level hit 50% and it lowered into the Pacific Ocean. If it had not malfunctioned I would still have my drone today. A couple of peeps here have analyzed my logs and the battery was in good condition and fully charged. I am told that I might have been able to make it home, yet I am not so certain about that because I took off above sea level. When I hit the stick up I did not seem to get lift. I have not opened a case with DJI yet, but I will.

A good read here.   However I was able to bring my drone home from over 2000 feet distance in critical low power mode.  You can fly the drone home. Factors for my getting this message was hovering in high winds doing a video shoot and by the time I flew home at 50mph ( tailwind ) I had gone from critical low power ( RED ) to normal 28% power ( Green )

PS maybe it is not the drone that malfunctioned but the pilot.  Sometimes we can be the cause of our own issues.   Look at my flight logs as well.   

http://forum.dji.com/forum.php?mod=viewthread&tid=89101

blackcrusader Posted at 2017-5-31 21:28
A good read here.   However I was able to bring my drone home from over 2000 feet distance in critical low power mode.  You can fly the drone home. Factors for my getting this message was hovering in high winds doing a video shoot and by the time I flew home at 50mph ( tailwind ) I had gone from critical low power ( RED ) to normal 28% power ( Green )

PS maybe it is not the drone that malfunctioned but the pilot.  Sometimes we can be the cause of our own issues.   Look at my flight logs as well.   

You know what, I'm happy that you were able to bring your drone home. I wouldn't wish anyone having to go through losing his or her drone.   If you want to be helpful here, then by all means be helpful. To make a snippet comment like "maybe it's the drone operator " really doesn't help.

Your situation was completely different from mine.  I never should've had a forced landing, and I was not getting lift by pushing the joystick up.  So if you couldn't tell me why they forced landing came on at 50% that is what I really want to find out?  I will be opening a case for DJI to see what they think.

Jeffyk Posted at 2017-5-31 22:24
You know what, I'm happy that you were able to bring your drone home. I wouldn't wish anyone having to go through losing his or her drone.   If you want to be helpful here, then by all means be helpful. To make a snippet comment like "maybe it's the drone operator " really doesn't help.

Your situation was completely different from mine.  I never should've had a forced landing, and I was not getting lift by pushing the joystick up.  So if you couldn't tell me why they forced landing came on at 50% that is what I really want to find out?  I will be opening a case for DJI to see what they think.

Good idea to refer it to DJI, but they will not tell you what happened. And they cannot do much without the flight data from the aircraft, and while it is feeding the fishes, it wont be much use. The data you get from your phone/tablet is rather minimal and probably will not give DJI much to go on. But by all means try, sometimes they offer a discount on the purchase of another aircraft.

BTW, the capacity of the battery is a calculated value, and it is provided more for your own benefit than that of the aircraft. At the point that the aircraft initiated auot-landing it regarded the battery voltage as being critical and that's why it landed, even though the capacity was shown as 50%. And during a landing triggered by the battery monitoring system, you cannot over-ride it.

Geebax Posted at 2017-5-31 22:44
Good idea to refer it to DJI, but they will not tell you what happened. And they cannot do much without the flight data from the aircraft, and while it is feeding the fishes, it wont be much use. The data you get from your phone/tablet is rather minimal and probably will not give DJI much to go on. But by all means try, sometimes they offer a discount on the purchase of another aircraft.

BTW, the capacity of the battery is a calculated value, and it is provided more for your own benefit than that of the aircraft. At the point that the aircraft initiated auot-landing it regarded the battery voltage as being critical and that's why it landed, even though the capacity was shown as 50%. And during a landing triggered by the battery monitoring system, you cannot over-ride it.

I concur fully, but would add that part one of the flight shows the battery showing 97% down to 80% in 5 minutes (which seems to be a good discharge rate), then 78% to 77% in 5:30.  Part two shows 76% 12 seconds later (presumably after a device restart) down to 60% at around 10 minutes (same discharge rate).  Resuming at 58% down to 44%in 14 minutes.  All fairly typical numbers for a full battery to be showing for a 25 minute flight.  I'd expect a bad or partly discharged battery to be jumping around a lot more randomly than the steady flow of numbers here, and it is supported by the final voltages recorded:

BatteryPower(%)	BatteryVoltage	BatteryVoltageDeviation	BatteryCell1Voltage	BatteryCell2Voltage	BatteryCell3Voltage	BatteryCell4Voltage
44	14.709	0.023	3.665	3.685	3.688	3.671

Of course the point that it is a calculated value is totally valid and we can't be certain what was going on without retrieving the wreckage.

And for the OP's benefit, the moves overriding the descent were making a difference and gaining altitude, e.g.


It is also shown in the flight track in multiple instances:

Wow, thank you so much for your helpful insight!  May I ask you how you did the analysis? Is that an actual image from the drones view?

Jeffyk Posted at 2017-6-1 06:38
Wow, thank you so much for your helpful insight!  May I ask you how you did the analysis? Is that an actual image from the drones view?

You can download the KML file and open it with google earth it shows your flight path.

Jeffyk Posted at 2017-5-31 22:24
You know what, I'm happy that you were able to bring your drone home. I wouldn't wish anyone having to go through losing his or her drone.   If you want to be helpful here, then by all means be helpful. To make a snippet comment like "maybe it's the drone operator " really doesn't help.

Your situation was completely different from mine.  I never should've had a forced landing, and I was not getting lift by pushing the joystick up.  So if you couldn't tell me why they forced landing came on at 50% that is what I really want to find out?  I will be opening a case for DJI to see what they think.

Do you think I should have had a forced landing from 35% battery?  regardless of what we think should happen is that for whatever my battery was showing critical low power.  So yes I was in an auto landing mode.  However by reading my down loaded manual and reading that and reviewing forums I was able to learn you can stop the descent and control the drones flight to a safe landing place.  IF my drone had descended from where it was at the time is would have gone down several thousand feet and crashed in the valley below somewhere.  

So with critical low power I flew home at full throttled and allowed my drone to descend at the same time.  By the time it reached home point my battery was no longer in critical low power and had green power levels and 28%.  I was flying at max altitude hovering with a strong tailwind so the software calculated that it was not safe to continue and I had to control my drones flight home.  

You maybe have been able to do the same thing if your drone was given the correct commands.  

http://www.phantomhelp.com/LogViewer/GKR0CDZMBVKQB2JDWS84/

Can you guys take a look at this.. My battery dropped from 18 - 0 instantly.. Seems to be a similar issue to this guy.

Geebax Posted at 2017-5-31 22:44
Good idea to refer it to DJI, but they will not tell you what happened. And they cannot do much without the flight data from the aircraft, and while it is feeding the fishes, it wont be much use. The data you get from your phone/tablet is rather minimal and probably will not give DJI much to go on. But by all means try, sometimes they offer a discount on the purchase of another aircraft.

BTW, the capacity of the battery is a calculated value, and it is provided more for your own benefit than that of the aircraft. At the point that the aircraft initiated auot-landing it regarded the battery voltage as being critical and that's why it landed, even though the capacity was shown as 50%. And during a landing triggered by the battery monitoring system, you cannot over-ride it.

There is some embedded data that does provide more data than what the user has access to. Of course, it would be best to have both the app and aircraft data to compare, but the embedded app data does help. The app data verifies the app settings and confirm any warning message that appeared to the user in the Go app that the aircraft data isn't completely equiped to relay, so it does serve a purpose.

The app data can either pick up on an obvious malfunction, user error (incorrect app settings etc.), or if there was a collision of some sort. If the data is inconclusive to either a malfunction or user error, then a discount may be possible. All of this, however, is handled on a case by case basis.

http://www.phantomhelp.com/LogViewer/GKR0CDZMBVKQB2JDWS84/ The same thing happened to me on the flight log.. In auto land mode I was cruising around using the left stick up to drain the rest of my battery when it suddenly dropped to 0 and dropped from the sky.. I think it has to do with the firmware update. DJI is taking a long time to respond to my case as this happened on Friday May 26th.. You are the third person I have seen where the auto-land function takes over and prevents the operator from delaying descent..

CAS-675740-D3N3L8

I am praying they get back to me soon as I have been without a drone for 1 week with no response.

Jeffyk Posted at 2017-5-31 17:16
I am really not sure. What I am sure of is that my Drone started auto landing when the battery level hit 50% and it lowered into the Pacific Ocean. If it had not malfunctioned I would still have my drone today. A couple of peeps here have analyzed my logs and the battery was in good condition and fully charged. I am told that I might have been able to make it home, yet I am not so certain about that because I took off above sea level. When I hit the stick up I did not seem to get lift. I have not opened a case with DJI yet, but I will.

The sooner that you start the claim process with Support, the better.

I would say to you sir, start a claim as soon as possible, because from my experience you won't get any conclusive answers regarding your scenario from any phone calls or forum posts.

Best case scenario you just have to wait 2-3 weeks for them to "Analyze" and then another 2-3 weeks for them to send you a drone if it was a malfunction.. So best case you'll be flying again in 1-1.5 months or in 2-3 weeks they tell you it was your fault give you 30% off... Either way, best case scenario you're out of a drone for a month (probably longer).

Best of luck to you my friend, try to keep frustration to a minimum on the phone and forum because any DJI representative that you talk to is unqualified to make any judgment regarding your case. Hopefully they can answer some of your questions.

Danielfonseca64 Posted at 2017-6-1 07:49
http://www.phantomhelp.com/LogViewer/GKR0CDZMBVKQB2JDWS84/ The same thing happened to me on the flight log.. In auto land mode I was cruising around using the left stick up to drain the rest of my battery when it suddenly dropped to 0 and dropped from the sky.. I think it has to do with the firmware update. DJI is taking a long time to respond to my case as this happened on Friday May 26th.. You are the third person I have seen where the auto-land function takes over and prevents the operator from delaying descent..

CAS-675740-D3N3L8

I assume this flight record is from a Phantom 4.  It shows you commencing the flight with 24½ minutes already on the clock--pretty much a flat battery right there.  The 21% reported battery is a calculated value, an estimate on the remaining capacity based on the discharge rate which varies based on factors such as hard flying, flying against the wind etc.  You really did not have any more battery left to discharge, and at most you should have been hovering a couple of feet off the ground to drain the rest of the charge, not heading off across the neighborhood.    You started with 3.4V per cell which is in the "caution" range.  Within seconds, they drop to less than 3.3V, into the critical range.   In the first few seconds, the calculations began updating and the estimates become lower and lower.  It reported critically low power and went into self-preservation mode and attempted to land, in autolanding mode.     The message "Critically Low Power. Aircraft Landing. Throttle up  to reduce the speed of descent and use sticks to avoid obstacles.;  Obstacle Avoidance will be disabled in landing." would have been flashed on your device screen.   However you continued to push the aircraft quite hard forward at 35mph, which resulted in a motor overloaded warning.  This also caused the power output and speed to be reduced.     At 25 minutes it warned "Battery: low voltage protection", indicating an imminent shutdown.  The cell voltages drop below 3V each.   I'm surprised it is still in the air!   Although you were pushing up, it only rose briefly before control was taken away from you (the small loop in the flight path shown below).  The last few seconds were a forced landing mode with the cells around 2.5V.   Eventually the capacity estimate catches up and the calculated battery value showed 0%.  It descended straight into the water (with a little forward movement) and the signal stops.  This is normal behaviour and nothing to do with a firmware update.

endotherm Posted at 2017-6-1 11:33
I assume this flight record is from a Phantom 4.  It shows you commencing the flight with 24½ minutes already on the clock--pretty much a flat battery right there.  The 21% reported battery is a calculated value, an estimate on the remaining capacity based on the discharge rate which varies based on factors such as hard flying, flying against the wind etc.  You really did not have any more battery left to discharge, and at most you should have been hovering a couple of feet off the ground to drain the rest of the charge, not heading off across the neighborhood.    You started with 3.4V per cell which is in the "caution" range.  Within seconds, they drop to less than 3.3V, into the critical range.   In the first few seconds, the calculations began updating and the estimates become lower and lower.  It reported critically low power and went into self-preservation mode and attempted to land, in autolanding mode.     The message "Critically Low Power. Aircraft Landing. Throttle up  to reduce the speed of descent and use sticks to avoid obstacles.;  Obstacle Avoidance will be disabled in landing." would have been flashed on your device screen.   However you continued to push the aircraft quite hard forward at 35mph, which resulted in a motor overloaded warning.  This also caused the power output and speed to be reduced.     At 25 minutes it warned "Battery: low voltage protection", indicating an imminent shutdown.  The cell voltages drop below 3V each.   I'm surprised it is still in the air!   Although you were pushing up, it only rose briefly before control was taken away from you (the small loop in the flight path shown below).  The last few seconds were a forced landing mode with the cells around 2.5V.   Eventually the capacity estimate catches up and the calculated battery value showed 0%.  It descended straight into the water (with a little forward movement) and the signal stops.  This is normal behaviour and nothing to do with a firmware update.

[view_image][view_image]

As you can see from this, It was in forced landing for 1 second before entering a free-fall and it was in auto-landing for about 10 seconds before I lost complete control. Is that by design?

endotherm Posted at 2017-6-1 11:33
I assume this flight record is from a Phantom 4.  It shows you commencing the flight with 24½ minutes already on the clock--pretty much a flat battery right there.  The 21% reported battery is a calculated value, an estimate on the remaining capacity based on the discharge rate which varies based on factors such as hard flying, flying against the wind etc.  You really did not have any more battery left to discharge, and at most you should have been hovering a couple of feet off the ground to drain the rest of the charge, not heading off across the neighborhood.    You started with 3.4V per cell which is in the "caution" range.  Within seconds, they drop to less than 3.3V, into the critical range.   In the first few seconds, the calculations began updating and the estimates become lower and lower.  It reported critically low power and went into self-preservation mode and attempted to land, in autolanding mode.     The message "Critically Low Power. Aircraft Landing. Throttle up  to reduce the speed of descent and use sticks to avoid obstacles.;  Obstacle Avoidance will be disabled in landing." would have been flashed on your device screen.   However you continued to push the aircraft quite hard forward at 35mph, which resulted in a motor overloaded warning.  This also caused the power output and speed to be reduced.     At 25 minutes it warned "Battery: low voltage protection", indicating an imminent shutdown.  The cell voltages drop below 3V each.   I'm surprised it is still in the air!   Although you were pushing up, it only rose briefly before control was taken away from you (the small loop in the flight path shown below).  The last few seconds were a forced landing mode with the cells around 2.5V.   Eventually the capacity estimate catches up and the calculated battery value showed 0%.  It descended straight into the water (with a little forward movement) and the signal stops.  This is normal behaviour and nothing to do with a firmware update.

[view_image][view_image]

I still had 2.876 Volts of battery in each cell, is this not enough battery to continue flight for another 10 seconds?

As I just posted in another battery thread, it's my understanding that the battery is in extreme danger of shutting down any time any cell drops below 3.0 volts.  

Danielfonseca64 Posted at 2017-6-1 07:49
http://www.phantomhelp.com/LogViewer/GKR0CDZMBVKQB2JDWS84/ The same thing happened to me on the flight log.. In auto land mode I was cruising around using the left stick up to drain the rest of my battery when it suddenly dropped to 0 and dropped from the sky.. I think it has to do with the firmware update. DJI is taking a long time to respond to my case as this happened on Friday May 26th.. You are the third person I have seen where the auto-land function takes over and prevents the operator from delaying descent..

CAS-675740-D3N3L8

"In auto land mode I was cruising around using the left stick up to drain the rest of my battery when it suddenly dropped to 0 and dropped from the sky.. "

That sounds kinda crazy. You were in autoland due to battery voltage and you intentionally  kept it in the air to further drain the battery?  Should have landed asap in my opinion.   Pilot error.

I once had an autoland happen right after launching the AC. Turns out the battery was too cold.  Learned that lesson.

Danielfonseca64 Posted at 2017-6-1 07:40
http://www.phantomhelp.com/LogViewer/GKR0CDZMBVKQB2JDWS84/

Can you guys take a look at this.. My battery dropped from 18 - 0 instantly.. Seems to be a similar issue to this guy.

You launched with a flat battery and you think there is a fault with the aircraft?

You are supposed to start a flight with a fully charged battery. Sometimes people may land  and take off again if there is enough charge, but at 21% that aircraft should be on the ground.

Danielfonseca64 Posted at 2017-6-1 13:58
As you can see from this, It was in forced landing for 1 second before entering a free-fall and it was in auto-landing for about 10 seconds before I lost complete control. Is that by design?

Auto-landing is the equivalent of a commercial aircraft pilot declaring "PAN PAN PAN, I have a fuel emergency, I need to land NOW!".  Forced landing  is the equivalent of "MAYDAY MAYDAY MAYDAY, I'm going down and I have no control".  The entire flight was on borrowed time.  In forced landing there is no elevator control--it is taken away from you--but you did have lateral and forward control, which you exercised (we see you pushing the right stick fully forward).  This is enabled so you can miss trees, small children and other obstacles as you land.  You got close to the [boat shed]? at the edge of the water but missed land by a short distance.  It was showing -1ft at the end (1 ft lower than your home point) , so whether it was in "free fall" or just out of radio contact due to obstructions is academic.  It would have been a fraction of a second only before it went swimming.


I still had 2.876 Volts of battery in each cell, is this not enough battery to continue flight for another 10 seconds?

No.  As stated above any time you go below 3v per cell it is a danger flag.  I expressed surprise the aircraft was even able to fly.  You went past low battery, past critical battery and the aircraft went in to screw you I'm landing! mode moments before the battery went in to I'm dead mode.  If you had the voltage displayed on the main page of the Go App, I'm sure it would have already changed from a green background through yellow and was showing red.  If you didn't see this or read any of the warnings, you clearly weren't monitoring your instruments and just flying by eye, watching the aircraft.

It didn't "drop from the sky", it was in controlled flight all the way until it touched down.  It's just that you were removed from controlling the height and the aircraft took over.

To be clear, a nominal 12V car battery could be considered dead flat yet it could still be measured at 6V.   That doesn't mean it still has half its charge.   A car needs 12V to run, any less is insufficient.  A 16V drone battery discharged to 12V is considered completely flat, and discharging it further risks permanent damage to the cells and fire.  And in future if you get 24.5 minutes flight time out of a battery, consider yourself lucky, and that battery needs recharging once it has cooled down.

Cabansail Posted at 2017-6-1 20:53
You launched with a flat battery and you think there is a fault with the aircraft?

You are supposed to start a flight with a fully charged battery. Sometimes people may land  and take off again if there is enough charge, but at 21% that aircraft should be on the ground.

Yeah. That's like a pilot taking off in a Cessna with a gallon of fuel on board and wondering why he is crashing a few minutes into the flight.