Battery cell 3 failure caused my Mavic to power off in flight!

[marklyn]

Ok, so I was coming back from a flight, and when I was about 500' from landing point I started noticicing an error concerning battery cell 3. I was in sport mode coming back since I was low on battery but I knew I had enough to make it back. As I was landing, maybe 1' from the ground the Mavic just shut off and it dropped. Fortunately this was soft grass so there was zero damage.When I took the battery out, it was swollen like a full tick on the bottom. This is an original battery that came with my combo pack purchase in July 2017 and has only been charged with DJI charging equipment and I've never seen an issue like this before. Build date on it is May 2017. It has 50 recharge cycles on it.

Would be appreciative if anyone could tell me if you've had a battery go bad like this and very quickly. If I had been 30 seconds out the Mavic would have been 180' in the air and I would be looking at a replacement now. I've never seen a battery issue before but is there a way to easily check this?
I'm very interested in going from what I think is a good battery to one that could have suddenly cost me my Mavic. What is the warranty on these batteries anyway?

Any insight into the logs would be appreciated (and why the Mavic just turned off suddenly).


DJI Flight log viewer - Phantomhelp

Airdata flight

 

[Goof]

Cell 3 dropped under 2v, which may have caused the battery to turn itself off. Any chance of a warranty replacement? Looks like it might have shorted internally.

 

[marklyn]

I posted on DJI forum also asking for insight from DJI but unless you post videos flying over daisy fields or compliment DJI, they usually don't respond.

 

[Cyberpower678]

Your battery was unbalanced at take off. Cell three had the lowest voltage and had to work harder to handle the load. It discharged to dangerously low values and got super hot as it continued to discharge. Battery is toast now.

 

[jaysrmc]

Ok, so I was coming back from a flight, and when I was about 500' from landing point I started noticicing an error concerning battery cell 3. I was in sport mode coming back since I was low on battery but I knew I had enough to make it back. As I was landing, maybe 1' from the ground the Mavic just shut off and it dropped. Fortunately this was soft grass so there was zero damage.When I took the battery out, it was swollen like a full tick on the bottom. This is an original battery that came with my combo pack purchase in July 2017 and has only been charged with DJI charging equipment and I've never seen an issue like this before. Build date on it is May 2017. It has 50 recharge cycles on it.

Would be appreciative if anyone could tell me if you've had a battery go bad like this and very quickly. If I had been 30 seconds out the Mavic would have been 180' in the air and I would be looking at a replacement now. I've never seen a battery issue before but is there a way to easily check this?
I'm very interested in going from what I think is a good battery to one that could have suddenly cost me my Mavic. What is the warranty on these batteries anyway?

Any insight into the logs would be appreciated (and why the Mavic just turned off suddenly).


DJI Flight log viewer - Phantomhelp

Airdata flight

I have had the same thing happen mid flight. Battery puffed up and down she went. Warranty is 6 months on Batteries. I had one with 13 charges fail.

 

[marklyn]

Wow. That's concerning. So would DJI cover something like this I wonder. Now I'm apprehensive about using the other two batteries since they came in the same order but it sounds like it's just a crap shoot...
Is there any warning signs I can look for in the other two batteries from Airdata UAV?

 

[Goof]

Keep an eye on the cell difference, if you have a battery that's consistently off I'd be looking at replacing it.

In flight you can tap the battery info in the top right and verify the cells are equalised before you fly (though this might not display minor cell differences) You can also set one of the C buttons to show/hide the battery info.

 

[marklyn]

Thanks Goof!

 

[Anthony]

Sorry to see you crashed I hope you manage to get back in the air soon ..

Just on the flying in sports mode to get back faster as you were low on power, sports mode will have put a higher discharge demand on the battery and the cell that was failing I think you would have possible had a better chance of getting back in P mode unless you had a strong head wind to deal with.

I have the battery cell information linked to the right rear button which I check a number of times during my flights this might be an idea to do going forward to help manage this issue if it were to happen again.

Good luck.

 

[Kilrah]

Yes they do cover this, and if it caused your mavic to crash they'd cover it too.

You need to deal with support, not the forum.

And yes when you have a battery issue sport mode is the last thing you want to use.

 

[RayOZ]

The battery is over 12 months old. It's out of warranty. Just be glad your MP survived unscathed. I am not sure if DJI would take responsibility.

 

[GavieboyDji]

Ok, so I was coming back from a flight, and when I was about 500' from landing point I started noticicing an error concerning battery cell 3. I was in sport mode coming back since I was low on battery but I knew I had enough to make it back. As I was landing, maybe 1' from the ground the Mavic just shut off and it dropped. Fortunately this was soft grass so there was zero damage.When I took the battery out, it was swollen like a full tick on the bottom. This is an original battery that came with my combo pack purchase in July 2017 and has only been charged with DJI charging equipment and I've never seen an issue like this before. Build date on it is May 2017. It has 50 recharge cycles on it.

Would be appreciative if anyone could tell me if you've had a battery go bad like this and very quickly. If I had been 30 seconds out the Mavic would have been 180' in the air and I would be looking at a replacement now. I've never seen a battery issue before but is there a way to easily check this?
I'm very interested in going from what I think is a good battery to one that could have suddenly cost me my Mavic. What is the warranty on these batteries anyway?

Any insight into the logs would be appreciated (and why the Mavic just turned off suddenly).


DJI Flight log viewer - Phantomhelp

Airdata flight

How low on battery was you?
I had mine fall out of the sky from about 100 feet straight onto concreate damaged everything.
but it was my fault because i was trying to get back my battery was really low it was at 6% when i got it above me starting to come down to land and it just dropped like a stone at 6% i couldnt beleve how puffed up the battery was and thats why it happend it disconnected its self.

 

[GavieboyDji]

24% 9.33V cell 1/ 3.470V Cell2/ 3.499V Cell 3/ 2.277V Total Devation>>> 1.193V

This is where your battery goes bad in cell 3 .
You was lucky because you was still 200 feet in the air when your battery started and 600 feet away from home point as well.

 

[Cyberpower678]

Keep an eye on the cell difference, if you have a battery that's consistently off I'd be looking at replacing it.

In flight you can tap the battery info in the top right and verify the cells are equalised before you fly (though this might not display minor cell differences) You can also set one of the C buttons to show/hide the battery info.

I have it tied to my C2 button. I always bring it up every 2 minutes to observe the balance. If it gets unbalanced by more than 0.05 volts then I know something is beginning to go wrong and will bring it in before the battery deteriorates even more.

 

[Cyberpower678]

How low on battery was you?
I had mine fall out of the sky from about 100 feet straight onto concreate damaged everything.
but it was my fault because i was trying to get back my battery was really low it was at 6% when i got it above me starting to come down to land and it just dropped like a stone at 6% i couldnt beleve how puffed up the battery was and thats why it happend it disconnected its self.

Battery shouldn’t fall out of the sky at 6%. The battery has some reserves in it even if it hits 0%

 

[GavieboyDji]

Battery shouldn’t fall out of the sky at 6%. The battery has some reserves in it even if it hits 0%

I thought that as well but when lipos get below 20% they fall off a cliff.
I've been told not to rely on the battery percentages from a few people in forum's.

 

[sar104]

I haven't seen a cell collapse like that before. The current spike at 1145 s after switching to sport mode killed it, but it was obviously sick before that.



The mid-air shutdown might have been the battery turning off or the supply voltage falling below the minimum for the FC to continue functioning. The record stops at 8.86 V; we know from previous battery disconnect events that the FC fails around 7 V.

 

[marklyn]

Thanks for the replies, I will try to keep an eye on my batteries before and during a flight.
Can I monitor them during a Litchi flight (since I don't use DJI Go that often)?

 

[Kilrah]

I thought that as well but when lipos get below 20% they fall off a cliff.
I've been told not to rely on the battery percentages from a few people in forum's.

Smart batteries like DJI's ones take that into account so percentage is linear. And 0 is reached/displayed before the "cliff".

Nothing it can do against a completely dead cell like this though. Crazy indeed how normal it looks until it drops, not typical of a cell with lower capacity at all.

My guess would be higher internal resistance (voltage is lower all the way) causing overheat, at some point it puffed and basically ceased functioning.

 

[Cyberpower678]

Smart batteries like DJI's ones take that into account so percentage is linear. And 0 is reached/displayed before the "cliff".

Nothing it can do against a completely dead cell like this though. Crazy indeed how normal it looks until it drops, not typical of a cell with lower capacity at all.

My guess would be higher internal resistance (voltage is lower all the way) causing overheat, at some point it puffed and basically ceased functioning.

A truly intelligent flight battery would forcibly set the power level down to 25% and force the aircraft to a forced RTH and landing the moment the deviation exceeds .2 volts.