If your Mavic falls out of the sky...

[Brojon]

There've been many conversations about Mavics just dropping out of the sky and one of the recurring "likely scenarios" is that the operator is assumed to have not inserted the battery properly and it somehow came loose. That may not be the case...
This past week I had my MP rise suddenly and smack a bridge - fall down go boom.
The MP is deader than a doornail but I noticed an oddity in that the battery was still showing on - two solids and 1 blinky LED. So I popped it into the charger and got the expected 1 LED blink but then it went out and the charger showed red.
Being an experienced electronics guy I said "hmmmm" and proceeded to disassemble the battery. BTW this is non-reversible since they use glue or ultrasonics to hold the case together.
Guess what I found? A clean separation of the positive terminal from the battery block to the controller! Now granted the drone fell 30 feet or so but it hit relatively soft mud. This is why the battery showed ok - it can only read the cells internally via the small cable with 4 wires reads each of the 3 cells.
So it would appear that DJI needs to check their quality on soldering the battery lugs - you can see the lug is welded to the actual battery post leading me to believe the board is assembled with the power leads, then the lug is soldered to the heavy wire likely by hand given the excess solder. You can see a little crystallization of the negative terminal showing a borderline solder joint but it is pretty solid - I tried to pull it off but ultimately I had to cut it.
Just thought I would toss this out there - I will be sending the photos to DJI once I get the myriad info they require to file a support incident. I don't expect anything from them except that they check into the issue.
Meanwhile I'd treat the batteries with extra care - vibration and jarring could lead to a failure if you have a battery with one of these poor joints.

 

[Chris_GREECE]

Great workaround. Please let us know for any answer from DJI.

 

[mph300]

I took apart a good battery to look at mod potential. I must say, the first thing I noticed was the two ugly solder joints. Now seeing this verifies it. Looks like no flux or burnt away flux and cold joint. Also, the sealer put on the joints in no way sealed the joint. Just my observations.

 

[Mitch]

There've been many conversations about Mavics just dropping out of the sky and one of the recurring "likely scenarios" is that the operator is assumed to have not inserted the battery properly and it somehow came loose. That may not be the case...
This past week I had my MP rise suddenly and smack a bridge - fall down go boom.
The MP is deader than a doornail but I noticed an oddity in that the battery was still showing on - two solids and 1 blinky LED. So I popped it into the charger and got the expected 1 LED blink but then it went out and the charger showed red.
Being an experienced electronics guy I said "hmmmm" and proceeded to disassemble the battery. BTW this is non-reversible since they use glue or ultrasonics to hold the case together.
Guess what I found? A clean separation of the positive terminal from the battery block to the controller! Now granted the drone fell 30 feet or so but it hit relatively soft mud. This is why the battery showed ok - it can only read the cells internally via the small cable with 4 wires reads each of the 3 cells.
So it would appear that DJI needs to check their quality on soldering the battery lugs - you can see the lug is welded to the actual battery post leading me to believe the board is assembled with the power leads, then the lug is soldered to the heavy wire likely by hand given the excess solder. You can see a little crystallization of the negative terminal showing a borderline solder joint but it is pretty solid - I tried to pull it off but ultimately I had to cut it.
Just thought I would toss this out there - I will be sending the photos to DJI once I get the myriad info they require to file a support incident. I don't expect anything from them except that they check into the issue.
Meanwhile I'd treat the batteries with extra care - vibration and jarring could lead to a failure if you have a battery with one of these poor joints.

Troubling.

 

[mph300]

Here is a look at the joints. Can not pull off with reasonable tug. Still looks questionable.

 

[f3honda4me]

Hmm interesting stuff. I'd be curious though if the crash caused the disconnect or not. Because your drone went up on its own and into a bridge, the battery was still properly functioning before the crash and not the cause of the crash. If it had disconnected the drone would have simply fallen from the sky, not gone up into an obstacle. In that scenario the most plausible cause there was the bridge causing the compass/mag to fail and the drone going into ATTI mode. Do you have the DAT file from that flight so that we can take a look?

 

[Brojon]

Hmm interesting stuff. I'd be curious though if the crash caused the disconnect or not. Because your drone went up on its own and into a bridge, the battery was still properly functioning before the crash and not the cause of the crash. If it had disconnected the drone would have simply fallen from the sky, not gone up into an obstacle. In that scenario the most plausible cause there was the bridge causing the compass/mag to fail and the drone going into ATTI mode. Do you have the DAT file from that flight so that we can take a look?

Sorry I wasn't clear. The battery was NOT the cause of the crash and I'm quite sure the fall is what jarred the terminal loose.
At issue here is the poor quality of solder joint and the relative ease with which it let go.
Say someone has a battery with a poor joint. The joint will be subjected to almost constant stresses as the drone get's flown with vibration, transportation, and let's not forget the heat expansion of those battery terminals.
So here you are flying and you start bucking the wind which causes a current surge with extra heat - I can see the terminal letting go at that point.
This is why I posted with the title I did - I wonder how many of the "just fell out of the sky" posts may have been the result of a shoddy terminal solder joint.

 

[locoman]

When my MP hit a power line, and fell to ground, about 16 feet. the batter fell out and got scraped up. Sent it back with the MP to DJI care refresh. They sent the old battery back with the old damaged props on a new bird. I had to change the props, since they were broken, but the battery still worked and charges normal and I think the cells are within specs, Have flown several times with the old battery. But will double check the cells voltages latter today to see if they really are within specs.

 

[Brojon]

When my MP hit a power line, and fell to ground, about 16 feet. the batter fell out and got scraped up. Sent it back with the MP to DJI care refresh. They sent the old battery back with the old damaged props on a new bird. I had to change the props, since they were broken, but the battery still worked and charges normal and I think the cells are within specs, Have flown several times with the old battery. But will double check the cells voltages latter today to see if they really are within specs.

Please don't generalize.
I'm not saying ALL batteries are cr@p - just that there may be issues with some that may explain the falling out of the sky issues we've all seen.

 

[locoman]

I am not generalizing. I had a specific incident, and I was surprised that they sent my original battery back because it was obvious that it had impacted the earth, and I am now concerned with the future reliability of that battery, especially based on what you found regarding poor solder connections.

 

[Brojon]

Ah! I get it now. I doubt you could tell. That would in fact be a point of concern for me too.

 

[StrayaMavic]

This is concerning, as it potentially raises my "cost per crash" which is already currently approx. $60 (blades and gimble cover).

Would I be correct to assume that it could also short something and start a fire if the wire crosses something else that it shouldn't?

 

[Brojon]

I dunno - if the wire popped loose I guess it could potentially short and LiPo cells aren't very fond of that.
I have not however heard of any MP's coming down in flames
That said I can't wait to get this thing out of my house opened up like it is. I found a battery disposal place today to drop it off.

BTW - I think you're the first person I'm aware of with a cost per crash metric

 

[locoman]

will check both of my batteries, the the cells seem to be with in spec. only .01 difference.

 

[StrayaMavic]

BTW - I think you're the first person I'm aware of with a cost per crash metric

haha, why not run it like a serious airline!

I figure, damaged blades aren't worth using if they put unnecessary stress on the motors and burn through battery faster. And you cannot remove the weird reflections in your footage if your gimbal cover is scratched. So I account for and track each crash as a way to measure my own improvement and the durability of the MP

I love data points.

 

[Brojon]

will check both of my batteries, the the cells seem to be with in spec. only .01 difference.

You can't check for this. If you look at the picture you'll see a connector with 3 red and 1 black wires. Those monitor the individual cells. At the front of teh board there are a couple of large small value resistors that are likely used to measure discharge and charge current. There's also a two lead black wires that have a thermistor at the end to measure cell temperature.
Anyway - given that the cells are measured BEFORE the output wires you can't correlate the cell values with the output.

 

[Brojon]

The other thing I forgot to mention is that the power cables are pretty stout and are likely under a bit of spring tension.
So if it lets go it would be very sudden and final - no stuttering as the wires bounced..

 

[StrayaMavic]

The other thing I forgot to mention is that the power cables are pretty stout and are likely under a bit of spring tension.
So if it lets go it would be very sudden and final - no stuttering as the wires bounced..

Skyfall

 

[Brojon]

Skyfall

Some guy from Germany just posted one where he was apparently landing and ... boom.
The data file doesn't show anything definitive - just an abrupt end about 30 meters off the ground.

 

[FlyGuy8675309]

This is concerning, as it potentially raises my "cost per crash" which is already currently approx. $60 (blades and gimble cover).

Your'e paying 2x more than your need to.,...just like a real airline. LOLOLOL