Mavic Pro 1 dropped out of the sky.

[555entropy]

We had just got a Mavic Pro (1, I know its old) from eBay five days ago, it looked fine, looking at the batteries that came with it they had ~26 charges, the battery was an original DJI. We flew it twice with no issues then today we were flying it again (third time) and right in front of us it dropped out of the sky. It was 200 feet up, about 20 feet in front of us hovering when the engine made a sound then silence and it just dropped. I looked at the flight logs and there really isnt anything I can see/understand that would explain why it lost power, but also understand if it did lose power it cant write the logs after that point. Ive exported and attached the DAT and .txt log, Ive also uploaded the log to Phantom Help and dont see anything that would cause this - it just seemed to lose power and drop.

What could possibly cause this? Multiple people were looking at it so we are sure both nothing hit it and it didnt hit anything, it was just hovering. The motors are still on the arms so they didnt shear off, one of the props broke off when it hit the ground but all four props are there. The battery was seated properly and at 39%.

Its too old to have a warrenty on but I am curious - has anyone ever had one lose power and drop out of the sky with no logs like this before? Id really like to understand why this can happen.

 

[slup]

...What could possibly cause this?

Hi there & welcome to the forum

Neither of the logs reveals anything suspicious, everything looks normal until the logs stop with the drone still airborne.

The battery voltage & overall behavior was normal
No abrupt unexpected or uncommanded attitude changes was recorded
The motor RPM's was normal
The FC command percent for the motors was normal
The motors where reported to be on
No error messages exists in the logs event streams

All this points towards a sudden power loss... either due to a battery disconnection or a component failure in the power system.

 

[Phantomrain.org]

So here is what sometimes happens to these older drones, the batttery swell up and can sometimes stretch the inner core of the battery compartment so that when you put in a newer batter becomes loose, It only takes a spit second for the battery to disconnect and the drone to fall out of the sky as this can happen when the battery swells as well. .

The battery swelling and disconnect on some of these drones was so common that many started using different methods to lock in the battery, such as a band or in our case an Air Tight Seal so that did not happen and the drone was not able to pop the battery out of it pocket.

Phantomrain.org
Gear to fly in the Rain. Land on the Water.

 

[Rockowe]

I had this Happen with my Mavic Pro (Zoom)

After a Long Non FLight.... I decided to fly again...

The Batteries were good - but swollen.
On TakeOff at 100ft... The swollen Battery extricated itself - ... and the Mavic Crashed - into may pieces...

Goodbye Mavic

 

[Cafguy]

I would think the battery swelled up and got dislodged. they are getting old. put a velcro strap around the Drone and battery to help keep it from popping out.

 

[Felix le Chat]

I would think the battery swelled up and got dislodged. they are getting old. put a velcro strap around the Drone and battery to help keep it from popping out.

...every time I read a post like this: I remind myself to strap the battery into my Mavic 2's... better safe than sorry. Zip tie, or velcro strap: it'll keep the battery connected.

 

[555entropy]

Thanks for the welcome slup o7

If a battery does swell up like that does it remain swelled or is there a chance it can return to its normal size? We didnt notice anything at the time of the crash, and measuring it now it is the same size on all sides as the rest of the batteries leading me to believe its most likely what slup said, a fault in the drone itself. The battery itself had been charged right before it was used and all checks on it even now report as normal. The drone was purchased on ebay so its hard to know its history but it doesnt feel right for a 3rd flight of a drone thats less then a week old.

 

[slup]

...If a battery does swell up like that does it remain swelled or is there a chance it can return to its normal size?

Yeah, the swelling can disappear... swelling is caused by electrolyte decomposition (comes from use/abuse & age) which generate gasses inside the LiPo pouch, with heat those gasses will expand & in severe cases make the outside of the battery pack bulge. If the battery pouches just contain a minor amount of gas, the bulging usually disappears when the battery cools down (but returns when the battery heats up again).

A Mavic Pro battery differs from a Mavic 2 Pro battery (see pics below)... in the sense that the Mavic Pro can withstand a minor swelling much better than the 2 Pro due to that the backside of the battery have a recess that can "swallow" a minor swelling without immediately starting to push the battery out from the drone... It's much more common that 2 Pro batteries gets dislodged from the drone due to swelling than on the older Pro.

If the battery isn't swollen now, it's more likely that the real cause of the power loss may be damaged/corroded/dirty battery/drone connectors... A badly clipped in battery... wear on the locking mechanism, either battery or drone side... or a glitching component in the drone.

Mavic Pro:


Mavic 2 Pro:

 

[Cafguy]

If you do not notice any signs of swelling on the ground like you say then swelling probably isnt your problem.

 

[BudWalker]

We had just got a Mavic Pro (1, I know its old) from eBay five days ago, it looked fine, looking at the batteries that came with it they had ~26 charges, the battery was an original DJI. We flew it twice with no issues then today we were flying it again (third time) and right in front of us it dropped out of the sky. It was 200 feet up, about 20 feet in front of us hovering when the engine made a sound then silence and it just dropped. I looked at the flight logs and there really isnt anything I can see/understand that would explain why it lost power, but also understand if it did lose power it cant write the logs after that point. Ive exported and attached the DAT and .txt log, Ive also uploaded the log to Phantom Help and dont see anything that would cause this - it just seemed to lose power and drop.

What could possibly cause this? Multiple people were looking at it so we are sure both nothing hit it and it didnt hit anything, it was just hovering. The motors are still on the arms so they didnt shear off, one of the props broke off when it hit the ground but all four props are there. The battery was seated properly and at 39%.

Its too old to have a warrenty on but I am curious - has anyone ever had one lose power and drop out of the sky with no logs like this before? Id really like to understand why this can happen.

The .DAT log file on the Mavic itself will have higher speed data that will show if the battery disconnected. Can you retrieve that FLY143.DAT and provide it via Dropbox or similar? Take a look here
How to retrieve a V3 .DAT File from the AC
to see how to retrieve it.

The motor voltage data in the on board .DAT will show a drop prior to shutdown.