hallmark007 Posted at 2017-4-28 07:08
Yes but I think the message is, your graph will give you a better indication of what signal you have rather than the amount of satellites shown, but the problem is most seem to rely on sat count, and some even ignore graph altogether.

I was only trying to clarify why 15 sats might not be as good as a better constellation of 10 for good positional control.  Lots of people would have trouble digesting that point without knowing why.

odradek Posted at 2017-4-28 06:10
I don't know if something is wrong with the battery, but two things I'm sure of is that when it crashed on the ground, the battery remained in its seat. I guess if it had not been properly inserted it would have been ejected during the crash. Second thing, the battery shows no play at all once inserted.
My conclusion is that if something went wrong with the battery, it was internal but not mecanical.

I would guess the impact might have been enough to properly reseat the battery if it dropped vertically, if, indeed, this the problem. I'm thinking one side latched, the other not, with just enough connection to launch but eventually breaking contact w/o actually separating from the AC. Would also explain why subsequent flights have been fine.

Good that there's no noticeable play. The report I referred to had two batteries out of the three he got with the Fly More combo exhibiting obvious-on-video play.

AG0N-Gary Posted at 2017-4-28 08:11
I was only trying to clarify why 15 sats might not be as good as a better constellation of 10 for good positional control.  Lots of people would have trouble digesting that point without knowing why.

I understand, good job.

hallmark007 Posted at 2017-4-28 08:35
I understand, good job.

Towards the end of the video, you can hear the motors reving up and down. Not sure why as it appeared to be flying level. At the very end, the motors sound like the power has been reduced and then immediately you can hear it hitting the ground still with a small amount of power. It all motors had stopped in the air, there should have been a longer break between the motors shutting down and the drone hitting the ground.

Ex Machina Posted at 2017-4-28 08:27
I would guess the impact might have been enough to properly reseat the battery if it dropped vertically, if, indeed, this the problem. I'm thinking one side latched, the other not, with just enough connection to launch but eventually breaking contact w/o actually separating from the AC. Would also explain why subsequent flights have been fine.

Good that there's no noticeable play. The report I referred to had two batteries out of the three he got with the Fly More combo exhibiting obvious-on-video play.

I don't know, and I can't know for sure, but it seems to me that it's not the most obvious reason (the battery being badly inserted). Of course I flew it twice (short flights) just after the incident, but I had flewn it a bit longer before that, with the same battery, without ever touching it, so I'm not sure this could be a valid reason...
Besides, the analysis made by BubWalker on post 25# shows that there was a drop to 7 Volts, not to 0, which seems to indicate the battery was still plugged...

Jenee 2 Posted at 2017-4-28 21:58
Towards the end of the video, you can hear the motors reving up and down. Not sure why as it appeared to be flying level. At the very end, the motors sound like the power has been reduced and then immediately you can hear it hitting the ground still with a small amount of power. It all motors had stopped in the air, there should have been a longer break between the motors shutting down and the drone hitting the ground.

Well, it's difficult to get a real account of what happened only from the sound of the video because, as I have stated here several times, the drone was 1.5 meters highe, maybe even less. So, the lapse of time between the stop of the motors and the crash was very very short.
What I'm sure of is that I very distinctly saw the motors stop. When I say 'stop', I mean that, instead of the blurry circle made by propellors in motion, I could see very distinctly each propellor stop moving and, then, instantly, the drone fall down on the ground. If the motors had slowed down but not stop, it would have fallen on the ground but not like rock free falling as it did. This I'm sure of. All the rest, the noises, the GPS, etc. I don't know for sure, as I'm a newbee, but the sudden stop of the propellors mid-air, this I'm sure of because I saw it in front of me.
Frankly, I'd prefer to find out that I am responsible for this and be able to correct it by changing what I would have done wrong, but, unfortunately, at the moment, most of the pieces of evidence tend to show that it is a manufacture default :
1) It happened to several MAVIC owner recently
2) 2 of them at least had their drone built the day after mine (probably same batch)
3) My DAT file indicate a drop of power from 11 to 7 volts all of a sudden on the 4 motors at the very end of the crash. (cf post 25#)
4) I think, from what I saw and did, that it is not the normal behaviour of a drone to shut all the motors at once in any other circumtances than after landing or with a battery down. Especially when you think that this drone is a tech marvel full of securities of all sorts.

Well, the Drone is now on its way to DJI facilities in Netherlands and I'll let you know when I get news.

odradek Posted at 2017-4-29 02:42
I don't know, and I can't know for sure, but it seems to me that it's not the most obvious reason (the battery being badly inserted). Of course I flew it twice (short flights) just after the incident, but I had flewn it a bit longer before that, with the same battery, without ever touching it, so I'm not sure this could be a valid reason...
Besides, the analysis made by BubWalker on post 25# shows that there was a drop to 7 Volts, not to 0, which seems to indicate the battery was still plugged...

The voltage drop to 7V is there one sample point before the recording stops.
This does indeed look like the power was cut. We are just lucky, that one data point of the dropping voltage was captured before it could not record anymore.

Question is still, why the power cut out. If you know that the battery was still on after the crash, I also can only think of a mechanical issue with the connector. Maybe the seating of the plug in the craft or the battery has play and thus the contacts do not fully mate. Still there is a chance of wrong battery installation as well. If these issues happen to a certain production batch, I would favor the theory of a too soft or misaligned placing of the contacts.
Anyway - this will stay speculation.

It could be helpful if someone who had this issue, could wiggle the battery with the Mavic powered and transmitting to see if there are voltage drops...

Hi Egika,

Here are two of my observations concerning the battery.

1) it was still in place and fully locked after the crash, that's for sure.
2) The possibility of a loose battery connection having been raised here before, I checked it on my MAVIC and, at least externally, there seemed to be no play at all when the battery was seated and locked. As for the contacts, since they're out of sight once the battery is in place, I can't tell for sure, but averything looked OK to me.

I will be interested to hear what, if anything, DJI conclude from your return.

In the meantime, to stop polluting the thread about power failure could the GPS weanies please take it to their own thread?

odradek Posted at 2017-5-2 22:58
Hi Egika,

Here are two of my observations concerning the battery.

Yeah, I would apply some pressure to the contact row on both the battery and Mavic body to see if something is flexing...

Egika Posted at 2017-5-3 00:35
Yeah, I would apply some pressure to the contact row on both the battery and Mavic body to see if something is flexing...

Unfortunately, the MAVIC is now on its way to DJI...
We'll see what they say about it...
Thanks for your interest anyway.

UPDATE ! UPDATE !

For those who are interested, I just got a notification from DJI Repair Center in Netherlands that my problem falls under the terms of their warranty system. Here are the remarks :
        Warranty, battery cut off. A new craft, gimbal, battery and props are needed
I guess and hope it's a good news for all people having a similar problem. :-)

not really. we still don't have any information, why this happens. i don't want my drone to go down like that. and it is somehow frightening, that this can happen at all.

As I was mentioned in this thread, my case finally moved forward, and also my warranty claim was accepted for the same reason. But DJI Germany not as fast as netherlands so I'll propably wait around 2 more weeks for my drone as damage assessment took 19 days...

SadOwnerOfMavic Posted at 2017-5-11 03:53
As I was mentioned in this thread, my case finally moved forward, and also my warranty claim was accepted for the same reason. But DJI Germany not as fast as netherlands so I'll propably wait around 2 more weeks for my drone as damage assessment took 19 days...

I'm glad to hear that DJI took good care of both of you. I've also noticed that the cluster of falling-from-the-sky posts seems to have dissipated, which is a good thing. It's unfortunate that these happened, but at least it doesn't appear likely to be an ongoing or very widespread problem.

UCBarkeeper Posted at 2017-5-11 03:44
not really. we still don't have any information, why this happens. i don't want my drone to go down like that. and it is somehow frightening, that this can happen at all.

The good news I mentionned was the fact that if, unfortunately, other MAVIC PRO owners were to encounter similar problems they would probably be covered by the warranty system. I still think it's better than nothing (or better than a useless wrecked drone...).

SadOwnerOfMavic Posted at 2017-5-11 03:53
As I was mentioned in this thread, my case finally moved forward, and also my warranty claim was accepted for the same reason. But DJI Germany not as fast as netherlands so I'll propably wait around 2 more weeks for my drone as damage assessment took 19 days...

Hello SadOwnerOfMavic,

This is a great news. Indeed, since your drone is still sleeping on the bottom of a lake in Poland (if I remember correctly), I was a bit worried for you. It's a good news for you and it's also a good news that DJI is taking full responsibilities when they know it's their fault.
Hope you get it back soon and can at last enjoy it.

DroneFlying Posted at 2017-5-11 04:29
I'm glad to hear that DJI took good care of both of you. I've also noticed that the cluster of falling-from-the-sky posts seems to have dissipated, which is a good thing. It's unfortunate that these happened, but at least it doesn't appear likely to be an ongoing or very widespread problem.

Let's hope it was only a bad batch and that we were the unlucky ones.

Fractures Posted at 2017-4-28 05:13
Are we sure these arent battery issues and not AC issues? OP said he has no problems on another flight leading me to believe that maybe something is wrong with his battery.
I dont think I would send the AC back

This.  Sudden voltage drop will stop the motors.

Never again flying Mavic over a lake before flying at least 2 hours over solid ground

SadOwnerOfMavic Posted at 2017-5-11 12:17
Never again flying Mavic over a lake before flying at least 2 hours over solid ground

That's my motto to now :-)

New update.
Eventually, after 2 weeks, I got my MAVIC back just in time for my holidays. I took it for a test fly and it's  amazing. I used 3 batteries and didn't get any power loss problem. I must say that they didn't repair it, they just replaced it with a unit built in september 2016. And concerning all the horror stories you can read around here about DJI support services, I don't know if I was lucky, but everything went fine, smooth and pretty quick for my problem to be solved. If you except the fact that I first found myself in posession of a non-working 1200€ drone, I'm quite happy with DJI now :-).

odradek Posted at 2017-5-21 01:02
New update.
Eventually, after 2 weeks, I got my MAVIC back just in time for my holidays. I took it for a test fly and it's  amazing. I used 3 batteries and didn't get any power loss problem. I must say that they didn't repair it, they just replaced it with a unit built in september 2016. And concerning all the horror stories you can read around here about DJI support services, I don't know if I was lucky, but everything went fine, smooth and pretty quick for my problem to be solved. If you except the fact that I first found myself in posession of a non-working 1200€ drone, I'm quite happy with DJI now :-).

thanks for sharing your experience man. Happy for you.
My build date is April 7th. hope i dont have any issues with it

BudWalker Posted at 2017-4-28 02:55
I looked at this flight. In summary, there was an unexplained complete power failure. It's just like several incidents that have been analyzed over in mavicpilots.com. In those incidents there was always the question - Did the battery become disconnected? Your incident provides an example where the battery didn't come loose.
Here is one of those threads
http://mavicpilots.com/threads/mavic-pro-dropped-out-of-the-sky.14482/

Obviously a catastrophic drop in motor battery.  But the fact that the Mavic actually recorded that drop indicates that other systems onboard were still powered.

I believe these batterys are typically comprised of 3 cells in series to obtain an operating voltage for the motors. Whereas the rest of the electronics is able to run on as little as 3.5 v.  I know these batteries are smart enough to load ballance, but I wonder if their "smarts" is triggering a cell shutdown.

Griffith Posted at 2017-5-26 11:08
Obviously a catastrophic drop in motor battery.  But the fact that the Mavic actually recorded that drop indicates that other systems onboard were still powered.

I believe these batterys are typically comprised of 3 cells in series to obtain an operating voltage for the motors. Whereas the rest of the electronics is able to run on as little as 3.5 v.  I know these batteries are smart enough to load ballance, but I wonder if their "smarts" is triggering a cell shutdown.

I don't know much about these batteries. But, is it possible there is a safety circuit built into these batteries that is supposed to detect a catastrophic discharge and will shut down the battery? A catastrophic discharge that would lead to a battery fire or explosion would be worse than a lost and/or damaged AC. I.e. a crashed Mavic would be a better outcome than a battery fire or explosion. Just spit balling here. I mentioned this once before but no one thought enough of the idea to comment.

BudWalker Posted at 2017-5-26 16:49
I don't know much about these batteries. But, is it possible there is a safety circuit built into these batteries that is supposed to detect a catastrophic discharge and will shut down the battery? A catastrophic discharge that would lead to a battery fire or explosion would be worse than a lost and/or damaged AC. I.e. a crashed Mavic would be a better outcome than a battery fire or explosion. Just spit balling here. I mentioned this once before but no one thought enough of the idea to comment.

I mentioned this once before but no one thought enough of the idea to comment.

Well, I know why I wouldn't be inclined to comment on your suggestion: because I probably know even less about the batteries than you do. I do know that my Mavic can't fly without one, but beyond that I'm generally going to keep my mouth shut.

I have seen, in some of the Phantom help  output,  references to Cell 1-3 battery health.  Bud, is there any data in the cvs file regarding individual cells?

Griffith Posted at 2017-5-27 06:57
I have seen, in some of the Phantom help  output,  references to Cell 1-3 battery health.  Bud, is there any data in the cvs file regarding individual cells?

The only info about individual cells in the .csv generated by DatCon are the cell voltages. That's not to say there isn't any more info in the .DAT. It could exist but DatCon isn't smart enough to know where it is.

I have similar the same problem.

And i have to say, the DJI Support is the worst i have ever seen.

They wan´t me to pay for the repair. I´m so angry right now.
It is ridicules, they send me a faulty Mavic and then they want me to pay for the damage.

Interesting, this has happened with my brand new Mini 2.
Got impatient with the whole Repair / Replacement service that I paid for the replacement option rather than assess and repair.

Waiting for instructions on how (and what) to send back.