MP Dropped from Sky

[lmayes69]

Good Morning ,
Sunday, I was flying my MP in the church parking lot. I canceled the RTH because I was less the 500 feet from where i was flying. Fly maybe another 2 minnutes then started to bring it to where i was going to land it and got a message about batter crital voltage landing now.. I still has 13%. began to land it and then the battery popped off and the drone just dropped. I JUST got this back from DJI Fiday and this was the first day I had been out .. I have attached the flight record. There wasnt much damage but now i get a vision error message

 

[sar104]

The data don't support your observation that "the battery popped off". What happened was that the cell 3 voltage collapses at the end and the aircraft shut down. If the battery ejected it was likely on impact.



If you want to retrieve the aircraft DAT file FLY007.DAT from the aircraft then it will likely confirm that.

 

[Recoveryone]

13%, you should have been near if not in auto RTH, poor mistake on your part. This will be seen as pilot error as you cancelled the safety protocals

 

[sar104]

13%, you should have been near if not in auto RTH, poor mistake on your part. This will be seen as pilot error as you cancelled the safety protocals

It's probably unwise but, that said, the battery should not shut down due to cell collapse at 11%.



However, looking closer at the cells, I wonder if it is possible that the cell voltages reflected the connector being pushed up at one side, increasing the resistance at the terminals. That might happen if the battery is swollen, and it might account for the original observation that the battery ejected.

 

[Recoveryone]

That was going to be my next question, was the age of the battery/number of cycles. Batteries over time will build up a resistance, so the numbers on the screen are just a gauge and should not be relied on for actual amount of power.

 

[sar104]

That was going to be my next question, was the age of the battery/number of cycles. Batteries over time will build up a resistance, so the numbers on the screen are just a gauge and should not be relied on for actual amount of power.

The battery was manufactured in June 2017, and showing 29 cycles.

The cell voltages are real and if the internal resistance of the battery rises then any current draw will cause external voltage drop. Voltage, power and energy are different things, of course.

 

[Recoveryone]

The battery was manufactured in June 2017, and showing 29 cycles.

The cell voltages are real and if the internal resistance of the battery rises then any current draw will cause external voltage drop. Voltage, power and energy are different things, of course.

With that being said, what did the OP go by to decide to keep flying?

 

[sar104]

With that being said, what did the OP go by to decide to keep flying?

That's a question for the OP, but I'd guess the smart-battery percentage, which was good until the voltage sag at the end.

 

[Recoveryone]

That's a question for the OP, but I'd guess the smart-battery percentage, which was good until the voltage sag at the end.

Acording to the OP he stated that the bird was RTH when he turned it off and kept flying. Normally you get "Low Battery" warning around 30% (unless you change it), RTH kicks in around 15-20%. (Unless you change it). The OP said he cancelled the RTH, which means the battery was near critical level already. I personally have had a battery go from 25% to 10% within seconds forcing my old Phantom 2 in auto land mode. The battery was nor old, but I came to the conclusion that it was faulty as the other battery I had brought with it was fine. There can/could have been other factors in play (heat, or wind) that may have caused the bird to exceed it normal power consumption.

 

[lmayes69]

I watched the drone fall and the battery was swollen. thats what made me think it disconnected from the drone and I lost power. I did cancel the RTH around 20 % when i got the message about the voltage being low and the air craft was landing automatically i didnt try to stop it just directed it to a safe area and the drop was only about 15feet from the ground when it lost power

 

[sar104]

I watched the drone fall and the battery was swollen. thats what made me think it disconnected from the drone and I lost power. I did cancel the RTH around 20 % when i got the message about the voltage being low and the air craft was landing automatically i didnt try to stop it just directed it to a safe area and the drop was only about 15feet from the ground when it lost power

Swollen before the flight, or after you recovered it?

 

[lmayes69]

Swollen before the flight, or after you recovered it?

after the battery was fine before .. or so I thought

 

[E90RAW]

I watched the drone fall and the battery was swollen. thats what made me think it disconnected from the drone and I lost power. I did cancel the RTH around 20 % when i got the message about the voltage being low and the air craft was landing automatically i didnt try to stop it just directed it to a safe area and the drop was only about 15feet from the ground when it lost power

How many of us cx RTH and fly when battery below 20%. I do this frequently but I keep my eye on the cell voltages and battery temp. As long as the individual volts stay above 3 or the average above 12 the batts are ok. The temp at > 50 celsius is problematic so I get worried when that occurs. A swollen battery makes complete sense, and the battery is old(2017) which contributes to oxidative damage internally. LiPo usually good for 100 cycles but age contributes to wear and tear.

 

[lmayes69]

gonna take a shot at sending it back to NI hopefully they will see it wasnt pilot error.

 

[timinator]

People who fly so close to the margin are likely to go off the page. That's what we see here. 13% is airborne equivalent of fumes in the tank.

 

[sar104]

People who fly so close to the margin are likely to go off the page. That's what we see here. 13% is airborne equivalent of fumes in the tank.

If not for the battery problem it would have been fine - the aircraft would have landed with 10% remaining.

 

[lmayes69]

I feel like it was the equiveltn of passing the gas station when the fuel light came on knowing you can go to the next one then your car blowing up before you get there. Even the app doesnt consider it " Critical battery until 10%. Thank you for the analysis of the data. Is there a way to monitor the battery cells and temp while flying. Considering my batteries are all old. Also are there any 3rd party batteries you could recommend or know where to get genuine ones at a lower discount than 90 usd each

 

[sar104]

I feel like it was the equiveltn of passing the gas station when the fuel light came on knowing you can go to the next one then your car blowing up before you get there. Even the app doesnt consider it " Critical battery until 10%. Thank you for the analysis of the data. Is there a way to monitor the battery cells and temp while flying. Considering my batteries are all old. Also are there any 3rd party batteries you could recommend or know where to get genuine ones at a lower discount than 90 usd each

I don't know how frequently or regularly you are using them, but with batteries of that age I would charge them and then run them down with the MP hovering over a soft surface, then check them for any swelling. My MP batteries still seem to be going strong (although it sees much less use now than the M2P), so I haven't explored replacement options.

 

[Dingo]

my MP 1 is 2017 all 3 batteries are fine and have around 46 cycles on them . I always land and power off with approx 20-25% battery remaining. I get 17-18 minutes flight time now compared to 20-21 minutes when new.

 

[Starz]

I walked away from a car that ran out of gas when I was 16. Never again.
Battery range for me means heading home at around 50 percent.
A little left in the tank is easier than a stroll down the road.