Battery failure.

[amstar]

Hello all,
So I flew ten missions yesterday, all without issues. I uploaded the data to healthy drones today and found that one battery consistently showed I cell out of range. So decided to deep cycle the battery like our old lipos. I put it in my Phantom Pro (yesterday I was flying Phantom Adv) and started the motors with the props off to get it down to about 8%. But around the 30% mark, the RC disconnected from the aircraft by itself. Nothing I could do including powering everything down, restarting etc. would link the controller back.
So I decided to another "smart battery". Now all of these had been run down to less than 50% from yesterday. This one linked automatically and everything seemed ok until the RC lost signal again. I tried linking it manually, didn't work.
So I tried a third one. This battery was fine. Everything linked, I did a gimbal calibration (just for the sake of it) and then powered everything down.
I loaded the data to healthy drones. Interestingly, the first flight data (with the battery with one cell off) was not even recorded on the Go app. The other two were there and it showed the battery health was fine.
So, now I'm in a quandary.
This never used to happen with P2V. And back then, I used to routinely run the batteries down to 8-10% and then proceed to download pics and videos. No healthy drones stuff, just recharge and fly.
This kind of makes me nervous.

 

[Blue Skies Media]

I haven't reseearched it, but do the P3 batteries need deep cycling? I thought they were Lithiums.

 

[amstar]

So I deep cycled that battery. Now everything is fine. Aircraft connected, took outside and flew around in gusty conditions. P3P was rock stable. Uploaded the flight log to HD, everything looks good.
Seems that taking off with a 100% charge is critical. Once the battery power drops below 30%, or an individual cell is below 3.6V, anything can happen.

 

[bbfpv]

Seems that taking off with a 100% charge is critical. Once the battery power drops below 30%, or an individual cell is below 3.6V, anything can happen.

This. Unfortunately a lot of people are figuring out this fact the hard way.

 

[alokbhargava]

Hello all,
So I flew ten missions yesterday, all without issues. I uploaded the data to healthy drones today and found that one battery consistently showed I cell out of range. So decided to deep cycle the battery like our old lipos. I put it in my Phantom Pro (yesterday I was flying Phantom Adv) and started the motors with the props off to get it down to about 8%. But around the 30% mark, the RC disconnected from the aircraft by itself. Nothing I could do including powering everything down, restarting etc. would link the controller back.
So I decided to another "smart battery". Now all of these had been run down to less than 50% from yesterday. This one linked automatically and everything seemed ok until the RC lost signal again. I tried linking it manually, didn't work.
So I tried a third one. This battery was fine. Everything linked, I did a gimbal calibration (just for the sake of it) and then powered everything down.
I loaded the data to healthy drones. Interestingly, the first flight data (with the battery with one cell off) was not even recorded on the Go app. The other two were there and it showed the battery health was fine.
So, now I'm in a quandary.
This never used to happen with P2V. And back then, I used to routinely run the batteries down to 8-10% and then proceed to download pics and videos. No healthy drones stuff, just recharge and fly.
This kind of makes me nervous.

This is an interesting catch. It clearly shows that at one point of time P3 senses bad battery status and disconnects with RC. I believe DJI should look into this use case and save many crashes by improving the logic or alarming the user.