DJI Drone explodes at 330 FT over US highway - Debris lands on highway I could have killed several people

[USMC_Rich]

Battery rocketed off drone trailing grey smoke in opposite direction from drone wreckage and was not recovered. No clue where it landed, I was more concerned about getting my drone off the highway. The battery clearly exploded if you look at the damaged bent battery connector pins, and the rear area looks like it was shot by a bullet.

Flight log DJI Flight Log Viewer - PhantomHelp.com


DJI Technical staff says Out of Warranty send $982

DJI stated
"First, we have coordinated your concern and provided the pictures you presented with our Engineers and they reviewed it. They have checked it and we coordinate this to our analysis team to check the flight records. I was able to get the result of the analysis and based on their investigation, they didn't say that the battery exploded while flying.

Since the unit is already out of warranty, I'm sorry but we cannot provide free service and the quotation should be settled for us to continue on the case. Please check the after-sales policy on this link:After-Sales Service Policies -

To help you with the quotation, I can offer a 10% discount and should you accept it, you can inform me here. Please take note that the final notice was already sent to you and the drone might be sent back to you unrepaired in case the quotation will not be settled for a certain period of time.

Looking forward to your early reply.

Thank you for choosing DJI Products."

 

[Saigondroner]

Holy Moly! What do you think happened? I've experienced a few catastrophic LiPo fires. Did it flame up mid air, and dropped to earth like a meteor?

 

[old man mavic]

welcome to the forum ,sorry for the circumstances of your post i makes you realise how much energy is stored in the lipos we use to fly

 

[slup]

Welcome to the forum even though it's under these dramatic circumstances.

Unfortunately it's not so much special that the log can revile regarding the flight itself ... You zipped around the parking lot some & then mainly ascended up to 102 meters while rotating were the log ends ... no warnings or other special thing's there. The temp were around 25C degrees & the winds between 9-11m/s but none of this had anything to do with this.





One thing found though, see below ... the battery used didn't behave healthy at all. Can't see anything else then this as a possible cause. Not surprised that DJI refuses this either, as if I'm remember correctly... the battery warranty time only is 6 month (log indicates that the battery were manufactured 21-Oct. 2017). Suspect that this battery have misbehaved already some time before this ... how have you stored it, treated it between flights & have you noticed any strange with this battery before this occurred? Have you followed the battery degradation trend over the year's in any way?

 

[Thomas B]

Sorry about the bad luck.
Welcome to the forum from the deserts of Arizona!

 

[sar104]

I don't see any evidence of an explosion - the wreckage looks to be basically in one piece, and what you might expect from a fast, nose-first impact on hard ground. Did you find the battery?

 

[BigAl07]

Welcome to the forum I don't suppose you have DJI Care Refresh on it?

 

[Sunshynff]

One thing found though, see below ... the battery used didn't behave healthy at all. Can't see anything else then this as a possible cause.

Well I hate sounding like I don't believe you, I truly want to, but a few things just add up. First and foremost, I have personally had 2 crashes/failures with DJI drones, in the 7 some odd yrs I've been flying, 1 Mavic and 1 P3P. I've been on hand and witnessed several others, plus as a firefighter and drone hobbyist, I have seen a fair share of catastrophic lipo failures.

I don't see how you could have had a lipo failure by the pictures you posted. Lipo batteries don't really blow up anyway, when they fail, they suffer from thermal runaway, witch starts as one component over heating and that leads to another component overheating and so on n so forth until the electrolyte polymer separating the lithium/positive layers from the negative carbon layers, evaporated and one of the cells break open. Lithium-ion, especially heated, does NOT like air, that's when it will burst into flames, very violently, with extreme heat, but not a true explosion. Unless it's in sealed air right container, which the casing on Mavic batteries are not air tight.

If your battery failed and it had a rapid thermal discharge, which could appear to be an explosion, you would have MASSIVE burns and melted plastic on the Mavic you posted pictures of. Also, would have probably melted most internal parts, like the gyro, altimeter or IMU, (I forget which is used to record yellow line in flight log), but that line, in the log pic above, is almost a perfect straight line from your final altitude straight to the ground. Even if it didn't melt, the violent nature of the failure would send unmelted parts flying In different directions.

Even though the log shows red starting at the 1min 5sec mark and a few other times, that's not really unhealthy behavior, it's giving a warning because one of the three cells in the Mavic battery becomes more than 1/10 of a volt (100mV) off from the other cells. I agree that's a goodsetting for an alarm, but that is an early warning, and often happens during a flight, especially with racing and freestyle quads where they can get as far as 3/4 of a volt(750mV) during high throttle punches,they call it voltage sag. The Mavic warns you more so you keep an eye on it and it doesn't get further apart or last too long of a time. So
I doubt that battery behavior was the cause of a catastrophic failure.

Again, I'm not trying to dismiss your story or imply that it's not true, but maybe you left something out, or forgot to tell us a piece of the puzzle. Like, did you find the battery? Do you have a picture of that? I had a lipo fire in my basement once, partly because I was being a cocky firefighter who wasn't afraid of a little lipo, and partly because I was charging on a concrete table and battery was in a lipo safety bag so I figured I was being plenty safe. It was a 4s 1300mah race battery, new/cheap charger that I ignored directions to. Had balance wire hooked up wrong, heard cracking; before I could get to table it broke open. At that time I had been on the job as firefighter for 16yrs, I had never ever seen something so small put off so much frame and heat, and so quickly, from nothing to holy **** my house is gonna burn down, in matter of seconds, it burned through the lipo bag like it was a plastic ziplock, and caught the drywall on fire that was 5ft away. I tell you about my lipo fire to explain why I am so surprised there's not a single burn mark or piece of melted plastic on your Mavic. So sorry one last time, 20+yrs of often putting out and investigating insurance fraud fires and meth lab fires and the stories we hear, can turn you into a cynic:.lol Let me know if you figure out the cause, hope you can get another one up n running, happy flying!

 

[USMC_Rich]

I don't see any evidence of an explosion - the wreckage looks to be basically in one piece, and what you might expect from a fast, nose-first impact on hard ground. Did you find the battery?

You must work for DJI... They need glasses also.

 

[appleguy010]

This is 100% not an explosion as evident from the plastic. Battery failure? Probably. It also could have been dislodged while flying. The wreckage is clearly from the collision with the ground from falling such a great height.

 

[slup]

You must work for DJI... They need glasses also.

Straight out from the log comes pretty much nada ... the only indication of anything is the battery cell deviation & the fact that the log stops mid air from what you have supplied.

If glasses is needed to see something obvious to you please tell what it is instead of playing hide & seek ...

As already questioned ... were are the burn marks? The Mavic looks like it hit solid ground from 102 meters ... yes, but why?

Battery disconnect?
Battery cell failure?
RC-AC total disconnect or only phone disconnect with following crash ... explaining log ending mid air?

Saw that you got similar question marks over at the DJI forum --> DJI Drone explodes at 330 FT over US highway

 

[BigAl07]

You must work for DJI... They need glasses also.

Easy there sir. These people are TRYING To help you figure out what happened to the best of their ability.

 

[GregE]

I appreciate how several have taken time to write detailed info/ analysis about this situation. A new user would be well advised to read a Lot to see the depth of knowledge and willingness to share before arguing.

The simulated explosion on the DJI forum thread video along with the high drama thread title caused a lot of click bait comments.

 

[MavicMan17]

This is 100% not an explosion as evident from the plastic. Battery failure? Probably. It also could have been dislodged while flying. The wreckage is clearly from the collision with the ground from falling such a great height.

There is in fact possible evidence in picture of the battery terminal, if you have ever seen a LiPo fire, or get hot enough to smoke, the smoke is white and will leave a white residue on any surface near it.
Not saying that's what happened but if the battery caught fire one would figure you'd see the smoke and be able to locate the battery easier. without pictures of proper evidence of a battery fire/ explosion then all anyone can do is speculate.

 

[MavicMan17]

On a side note, without the proper evidence, it is hard to help the OP. any further than anyone already has. One could speculated that this post created to spark debate.

there is evidence to that however and the proof is in the DJI forums where this same post was made and got the same results.

not gonna lie I was looking forward to reading this post due to the title and it definitely has not lived up to the name.

 

[USMC_Rich]

You must work for DJI... They need glasses also.

Well I hate sounding like I don't believe you, I truly want to, but a few things just add up. First and foremost, I have personally had 2 crashes/failures with DJI drones, in the 7 some odd yrs I've been flying, 1 Mavic and 1 P3P. I've been on hand and witnessed several others, plus as a firefighter and drone hobbyist, I have seen a fair share of catastrophic lipo failures.

I don't see how you could have had a lipo failure by the pictures you posted. Lipo batteries don't really blow up anyway, when they fail, they suffer from thermal runaway, witch starts as one component over heating and that leads to another component overheating and so on n so forth until the electrolyte polymer separating the lithium/positive layers from the negative carbon layers, evaporated and one of the cells break open. Lithium-ion, especially heated, does NOT like air, that's when it will burst into flames, very violently, with extreme heat, but not a true explosion. Unless it's in sealed air right container, which the casing on Mavic batteries are not air tight.

If your battery failed and it had a rapid thermal discharge, which could appear to be an explosion, you would have MASSIVE burns and melted plastic on the Mavic you posted pictures of. Also, would have probably melted most internal parts, like the gyro, altimeter or IMU, (I forget which is used to record yellow line in flight log), but that line, in the log pic above, is almost a perfect straight line from your final altitude straight to the ground. Even if it didn't melt, the violent nature of the failure would send unmelted parts flying In different directions.

Even though the log shows red starting at the 1min 5sec mark and a few other times, that's not really unhealthy behavior, it's giving a warning because one of the three cells in the Mavic battery becomes more than 1/10 of a volt (100mV) off from the other cells. I agree that's a goodsetting for an alarm, but that is an early warning, and often happens during a flight, especially with racing and freestyle quads where they can get as far as 3/4 of a volt(750mV) during high throttle punches,they call it voltage sag. The Mavic warns you more so you keep an eye on it and it doesn't get further apart or last too long of a time. So
I doubt that battery behavior was the cause of a catastrophic failure.

Again, I'm not trying to dismiss your story or imply that it's not true, but maybe you left something out, or forgot to tell us a piece of the puzzle. Like, did you find the battery? Do you have a picture of that? I had a lipo fire in my basement once, partly because I was being a cocky firefighter who wasn't afraid of a little lipo, and partly because I was charging on a concrete table and battery was in a lipo safety bag so I figured I was being plenty safe. It was a 4s 1300mah race battery, new/cheap charger that I ignored directions to. Had balance wire hooked up wrong, heard cracking; before I could get to table it broke open. At that time I had been on the job as firefighter for 16yrs, I had never ever seen something so small put off so much frame and heat, and so quickly, from nothing to holy **** my house is gonna burn down, in matter of seconds, it burned through the lipo bag like it was a plastic ziplock, and caught the drywall on fire that was 5ft away. I tell you about my lipo fire to explain why I am so surprised there's not a single burn mark or piece of melted plastic on your Mavic. So sorry one last time, 20+yrs of often putting out and investigating insurance fraud fires and meth lab fires and the stories we hear, can turn you into a cynic:.lol Let me know if you figure out the cause, hope you can get another one up n running, happy flying!

 

[MavicMan17]

@USMC_Rich did you find the Battery?, if so post a few pictures of the battery. that will solve any debate on what is the true cause of this unfortunate event.

 

[sar104]

You must work for DJI... They need glasses also.

I guess that clarifies that you are not looking for independent assessment on this. I also notice that you declined to answer the question on whether you found the battery. As noted above, LiPo batteries fail by thermal runaway, and yet there is no evidence of thermal damage in the out-of-focus photos that you posted. The log ends when you centered the throttle from full climb - a common cause of an insecurely latched battery being dislodged enough to kill the power. Unless you can produce the remains of the battery to demonstrate that it exploded then that hypothesis remains in the extremely unlikely category.

 

[USMC_Rich]

@USMC_Rich did you find the Battery?, if so post a few pictures of the battery. that will solve any debate on what is the true cause of this unfortunate event.

Battery rocketed off drone in opposite direction from drone wreckage and was not recovered.

 

[sar104]

Battery rocketed off drone in opposite direction from drone wreckage and was not recovered.

If it were to fail propulsively at one end, rather than explode, unusual though that might be, it also could conceivably cause the damage you saw. So you actually saw the battery ejected at high speed? If so then you really need to find it.