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

[marklyn]

Actually, it looks like my current Airdata subscription will allow me to review the battery/cell voltages. It may not do fancy graphs/trends like the gold version but it seems to me that all I have to look for is a cell voltage deviation for a minute or more of 0.07 or so it says on their battery voltage page. Unless someone tells me the gold will provide better information, I think I'll pay attention to the battery voltages with my current subscription.
Caveot: I still realize that the cell 3 in this failed battery didn't really show any significant problems until this very flight. So still a bit nervous but will watch the voltage deviations.

 

[marklyn]

Follow up: I emailed Airdata UAV to ask them what more information could be garnered from a higher sub account to determine potential battery issues.
They gave me a 360Gold account for a couple of weeks to try out (Thanks!)
All in all, I really didn't see anything overly useful in the additional account that would have clearly warned me about this potential battery failure.
There is one area where you can click on a specific battery to see a list of all battery deviations by date and severity, which is nice, but you can still manually do this in a lower sub account.
It just takes more time to go through every flight to see what (if any) deviations you might have.

I emailed them again and asked if they would consider putting some type of notification pop up or some way to let the user know that there were major cell deviations on a flight.
I asked them to consider making this a free service to all subs and for paid subs there could be more detailed info (as there is now). Hope they consider this.

 

[Turn11]

It does seem expensive, but on the bigger scheme of things, you should consider it the running cost of this hobby. $84 per year might have avoided you crashing a $1000 drone. I bought the 1 year subscription, as it was little cheaper. I think sometimes, they give a discount for upgrading. Wait for that.

IMHO, it is worth it for the reason you mention. I like it for the history also. Some will agree, some will disagree. (Ford vs Chevy) Percentage is nice but after reading about a lot of failures would it be safer to monitor battery voltage instead of percentage.

@msinger @sar104

Are these threads still valid for the M2.
Monitor battery voltage to watch for signs of failure

Monitoring battery Percentage vs Battery Voltage

 

[marklyn]

Turn11, thanks for the reference links, very interesting and think I will focus on the voltages as well. I'll also be checking every flight to see if there are major deviations in the voltages for any battery used.

One question for clarification, when I read watch the battery voltages on the screen, am I correct in that the voltage represents the addition of the 3 cells divided by 3 to give you the running voltage. If this voltage dips below 3.30 then I should seriously watch this or return home... is that right?

 

[sar104]

Turn11, thanks for the reference links, very interesting and think I will focus on the voltages as well. I'll also be checking every flight to see if there are major deviations in the voltages for any battery used.

One question for clarification, when I read watch the battery voltages on the screen, am I correct in that the voltage represents the addition of the 3 cells divided by 3 to give you the running voltage. If this voltage dips below 3.30 then I should seriously watch this or return home... is that right?

The cells are in series - the operating voltage is the sum of the three cell voltages.

 

[Davidvan]

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.

View attachment 48250

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.

Where do we get that battery info from, it would be interesting to check that from time to time ?

 

[Kilrah]

am I correct in that the voltage represents the addition of the 3 cells divided by 3 to give you the running voltage.

No it's not divided by 3, all 3 cell voltages are measured independently. The single cell voltage you see on the main screen is the lowest of the 3.

 

[Keule]

Where do we get that battery info from,

In GO4, look at this screen:

 

[Hayabusa]

In GO4, look at this screen:

View attachment 48530

Ok- so when looking at this page, its bad if I see a difference between the 3 cells? How much difference/deviation? To clarify, this needs/should be checked while in air prior to flight and periodically during?
You guys have me nervous now
Thanks
Mike

 

[Keule]

so when looking at this page, its bad if I see a difference between the 3 cells?

If you see a difference of ~ 0,1v on on of the cells (let's assume you're seeing 3.7v) over an extended period of time (say 30 seconds or more) while flying, bring the bird close to home. (flying not aggressive)
Look at the voltages again, if the volts are levelling back (lets say for example, 3.75v each), you are good to go.
If they are not level, being more than ~0.1v apart, land.

DJI has a builtin error detection which will show a warning if the voltage levels differ too much.

this needs/should be checked while in air

yes

and periodically during?

yes.

I have assigned button C1 to bring up the battery info screen while in flight.

Don't get nervous - once you get used to above procedure, look at your individual cell voltages every few minutes, you sould have confidence in your equipment.

 

[Hayabusa]

Thanks so much
Assigning button tonight.
Mike

 

[maxxrussia]

I was flying my Mavic Pro Platinum and from talking to a drone expert. He looked at my air data flight log and said that I was having bad cell deviation in cell 3... He stated that I was having 100% radio transmission signal and then nothing. So he said he was certain it fell out of the sky like a brick. Now I am over here trying to calculate the horizontal projectile motion from its height, speed and weight with its last known recorded coordinates. day 2 now and still no luck finding it.

If anyone has any help or pointers on what I can do from here that would be great. I got the drone only a month ago so I have only had a total of maybe 10 or 15 total cycle charges on it. I hope I can find it so I can reach out to DJI and see what they can do for me. Because none of this was supposed to happen but I guess accidents happen. My battery at the time of crash was 75%.

 

[sar104]

I was flying my Mavic Pro Platinum and from talking to a drone expert. He looked at my air data flight log and said that I was having bad cell deviation in cell 3... He stated that I was having 100% radio transmission signal and then nothing. So he said he was certain it fell out of the sky like a brick. Now I am over here trying to calculate the horizontal projectile motion from its height, speed and weight with its last known recorded coordinates. day 2 now and still no luck finding it.

If anyone has any help or pointers on what I can do from here that would be great. I got the drone only a month ago so I have only had a total of maybe 10 or 15 total cycle charges on it. I hope I can find it so I can reach out to DJI and see what they can do for me. Because none of this was supposed to happen but I guess accidents happen. My battery at the time of crash was 75%.

The trajectory can be estimated, but not without the flight log.

 

[maxxrussia]

The trajectory can be estimated, but not without the flight log.

Should I post the link to my flight log from Air Data? Thanks!

 

[sar104]

Should I post the link to my flight log from Air Data? Thanks!

Yes - that will work as long as you enable download of the original log file.

 

[BossBob]

Could the cause of the mid air shut down be simply that the battery was puffed enough to force it to physically disconnect the battery power connection but not to eject the battery from the drone. Although the poster removed the battery we don’t know how securely it was attached.