Mavic turned off suddenly

[aldo109]

Hi Everyone,

I'm Aldrian and this is the first time I'm posting in this forum.
I've been following quite a number of threads from this forum before to grasp the wisdom from most of you on how to use Mavic.

I'm a Mavic Pro gen 1 pilot for quite sometime and I did crash my drone before. However, a few months back I lost my drone at sea when I my friend borrowed my drone.

According to him, the chronology was, he started the drone, upon flying it around, it fell to the sea a couple minutes after flying.
He said, the screen turned black and white and the drone turned off by itself before it fell down to the sea.
No prompt or warning appeared on both the remote or phone and, according to him, the sky was clear no obstruction or even eagles on sight.

I've attached the flight log along with this post, did try to see it in the flight log viewer, but with my über limited knowledge of aviation data, I can't get into any conclusion.

The only thing I can conclude is that the flight time is roughly 1m40s, the estimate where it fell, and also the message indicate there's a signal loss between the drone and the remote. But I don't seem to find any error like motor error or obstacle etc.

I do hope anyone of you can help me to understand this situation, since losing a drone in the sea is just... painful.
When I crashed before, at least I can still pick it up and fix it, but for this special case... it's impossible.



Cheers

 

[Phantomrain.org]

Auto Landed in the Sea low battery:
You took off with a battery that was just very very low.

The battery basically controlled your whole flight out so you had very few options.
Poor Battery Management is the reason for a lot of these flushes.

Have to brush this off as the dues paid to becoming a Pilot making good
decisions on the flight.

Might consider a Rescue Jacket in the near future.

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

 

[Meta4]

I lost my drone at sea when I my friend borrowed my drone.

According to him, the chronology was, he started the drone, upon flying it around, it fell to the sea a couple minutes after flying.

Your friend launched without charging the battery and it was already very low.
On launching the battery indicator showed 26% but the battery had been sitting around discharging for some time so the % indication was false.
47 seconds into the flight, one of the battery cells dropped below 3.3 volts (critical low level).
The whole battery shut down at the end of data with the voltage of Cell 2 down to 2.2 volts.

 

[aldo109]

Thank you for all of your reply.

So then, can I conclude that this happen due to the pilot's fault for not using a charged battery?

I am actually shocked he flew with a 25% battery. In all of my experience 30% is the bottom line for flying a drone back to home, not even starting it up.

One quick question before I wrap this up, as far as I know, there should be warning if the battery is 30% and lower yet my friend said there was no warning. Can you alter this setting?

 

[Meta4]

So then, can I conclude that this happen due to the pilot's fault for not using a charged battery?

Yes

I am actually shocked he flew with a 25% battery.

It was actually lower than that as the % indicator is only accurate when the battery is full to start the flight.

One quick question before I wrap this up, as far as I know, there should be warning if the battery is 30% and lower yet my friend said there was no warning. Can you alter this setting?

Yes .. and the data shows that it had been reset to 19%.

 

[boblui]

So then, can I conclude that this happen due to the pilot's fault for not using a charged battery?

The prime cause is the battery being faulty. One of the cells had the voltage dropped a LOT more than the others. If left unattended, crashing is just a matter of when.



If the voltage deviation occurs prior to take off, you will get this warning but unfortunately it occurred during the flight in your case.

I am actually shocked he flew with a 25% battery. In all of my experience 30% is the bottom line for flying a drone back to home, not even starting it up.

It's perfectly OK to launch at 25% as long as you are not going to fly far away and reserve sufficient battery for RTH in case of signal disconnection. If the battery was normal. The craft would have RTH safely.

The complication here is the disconnection which should not have occurred at such a short distance ( 280 ft ). May be there was something not shown in the map blocking the signal ? From the last record of the log the craft was doing autolanding when there was still 21 % battery. This does not look right to me because at that distance my M2 will not trigger autolanding until the battery hit 12%.

 

[Meta4]

The complication here is the disconnection which should not have occurred at such a short distance ( 280 ft ). May be there was something not shown in the map blocking the signal ?

Signal was lost because the Mavic was lost when the battery shut down.
When there's no Mavic, there's no signal.

 

[boblui]

Signal was lost because the Mavic was lost when the battery shut down.
When there's no Mavic, there's no signal.

From the .DAT log the loss of signal was intermittent and occurred before the battery shut down. The time resolution of the .TXT log is not high enough to show that.

 

[THE CYBORG]

And he is still your friend ?

 

[Scubadiver1944]

Loaning a Mavic 1 Pro to a "friend" who doesn't appear to know or heed warnings either on the UAS or the RC didn't end well. Let's hope his "friend" adequately compensated the OP for his apparent inattention.

And he is still your friend ?

 

[Capt KO]

Sad. Make him/her reimburse. Lesson learned

 

[DanMan32]

The prime cause is the battery being faulty. One of the cells had the voltage dropped a LOT more than the others. If left unattended, crashing is just a matter of when.

View attachment 119533

If the voltage deviation occurs prior to take off, you will get this warning but unfortunately it occurred during the flight in your case.

View attachment 119535


It's perfectly OK to launch at 25% as long as you are not going to fly far away and reserve sufficient battery for RTH in case of signal disconnection. If the battery was normal. The craft would have RTH safely.

The complication here is the disconnection which should not have occurred at such a short distance ( 280 ft ). May be there was something not shown in the map blocking the signal ? From the last record of the log the craft was doing autolanding when there was still 21 % battery. This does not look right to me because at that distance my M2 will not trigger autolanding until the battery hit 12%.

Battery could have simply been out of balance. That can happen if Battery had gotten into self discharge, then used without first being recharged.

 

[JackL]

That friend needs to swim out there and get it for trying to fly it with a dead battery!

 

[Nightowl1234]

Auto Landed in the Sea low battery:
You took off with a battery that was just very very low.

The battery basically controlled your whole flight out so you had very few options.
Poor Battery Management is the reason for a lot of these flushes.

Have to brush this off as the dues paid to becoming a Pilot making good
decisions on the flight.

Might consider a Rescue Jacket in the near future.

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


View attachment 119532

I have taking off Mavic Air 2 with a low battery 25" and ran into the same problem with a disconnect

 

[zeusfl]

Most likely your battery has a bad cell and is not balancing. The IR from that cell has to be pretty high. I will wont use that battery other than bench settings.

 

[slup]

Battery could have simply been out of balance. That can happen if Battery had gotten into self discharge, then used without first being recharged.

Don't think that was the case here, the cells were in balance until 11sec into the flight ... then cell 2 failed major. Perhaps not a mystery as we don't know anything about how this battery have been treated & it's pretty old.

 

[GFields]

Sorry for your loss.

 

[DanMan32]

Don't think that was the case here, the cells were in balance until 11sec into the flight ... then cell 2 failed major. Perhaps not a mystery as we don't know anything about how this battery have been treated & it's pretty old.

View attachment 119551

Cell 2 may have been within tolerance in the beginning but still had significant deviation from the start, particularly when you compare level and deviation between the other two.

I would be curious to see what the levels and deviation were right after the last full charge.

 

[slup]

Cell 2 may have been within tolerance in the beginning but still had significant deviation from the start, particularly when you compare level and deviation between the other two.

I would be curious to see what the levels and deviation were right after the last full charge.

Well ... all outside the log is pure speculation so really impossible to tell. But self discharge functionality don't go down to 26% for DJI batteries ... so we can assume that the battery have been flown down to that percentage level.

The cell voltage immediately at motor start was 3,7V 3,65V & 3,71V so nothing outside the normal there & remained at those levels through the motor start ... but as soon the current draw increased due to the actual take off & maneuvering cell 2 rapidly dragged behind. At 10,8sec the deviation went to 0,11V and it's here the first throttle, elevator & aileron stick inputs are applied. After this, cell 2 voltage dropped like a rock ...

Batteries doesn't last forever ... at some point in time they will fail & that happens usually when it's put under load & they are much more prone to fail when nearly empty.

 

[aldo109]

Wow thank you so much for all the replies!
I am really grateful that I got in touch with all of you in this forum, all of you are really helping.

And he is still your friend ?

Hahahahaha! Apparently, he is still my friend... but for sure I am not letting him close to any of my drones anymore.
And also, everytime I am in conversation with him I can always mention this incident... ?

Sorry for your loss.

Thank you very much...

That friend needs to swim out there and get it for trying to fly it with a dead battery!

He did, according to him. He may be exaggerate the story though.

_____

For all of you who are trying to explain the cause, thank you very much! I am now agree that the main problem is the battery, though I'm still hate the fact that he push to fly the drone with the battery below 30%.