https://forum.dji.com/forum.php? ... 906&pid=2526423

A very informative topic.
I didn't know about the rules described here. I was also flying on  partially discharged batteries. I didn't know what the threat was.

Yes, it's not like petrol in a car where the expected power is the same at 40% of a tank compared to 100% of a tank. The power in a partially used battery isn't constant. There have been a few topics here where the cause was people flying on partially used batteries. Using the partially used battery in the same day is ok but if you leave it for more than a day or more you are more than likely going to run into trouble...

Thanks for the nomination ;)

IMO, things could be so easily solved if DJI made an "idle timer" inside the battery controller and warn the users before they use half used and uncharged batteries.

Afterall they have built a timer inside the smart controller...

Hello there vg1. Good day and thank you for sharing these information with us. I will cascade this post to the designated DJI department for further attention. Thank you and have a nice day.

FriedChicken_II Posted at 7-28 18:34
Thanks for the nomination ;)

IMO, things could be so easily solved if DJI made an "idle timer" inside the battery controller and warn the users before they use half used and uncharged batteries.

Excellent idea. Hope DJI will look in to this. It could certainly save some problems.

Interesting read.  Thanks for sharing.

But there are wrong information. Depleted battery (at 10%) will never be dislpayed as 40% the next day. My MA2 with latest fw. performs forced landing at 10% of charge and refuses to take off. Only irresponsible operator would have tried to use this battery again and very likely it wouln't be possible to take off again.
Of course it is good practice to charge battery fresh for every flight to have usual flight time. But if You are aware of limitations of performance, You can fly with partially charged battery. Better value to watch is flight time. I have 27 minutes on fresh full battery, so I can make one 12 minutes flight on one place and another 12 minutes of flying on a different spot to play it safe, if the conditions (wind ect.) are about the same. If the battery wasn't recharged that day, flight time can be reduced significantly, so it is better to discharge the battery to at least 30% and recharge for flying next day.

virtual Posted at 7-30 12:59
But there are wrong information. Depleted battery (at 10%) will never be dislpayed as 40% the next day. My MA2 with latest fw. performs forced landing at 10% of charge and refuses to take off. Only irresponsible operator would have tried to use this battery again and very likely it wouln't be possible to take off again.
Of course it is good practice to charge battery fresh for every flight to have usual flight time. But if You are aware of limitations of performance, You can fly with partially charged battery. Better value to watch is flight time. I have 27 minutes on fresh full battery, so I can make one 12 minutes flight on one place and another 12 minutes of flying on a different spot to play it safe, if the conditions (wind ect.) are about the same. If the battery wasn't recharged that day, flight time can be reduced significantly, so it is better to discharge the battery to at least 30% and recharge for flying next day.

It's just an example. What I really meant is that your battery loses accurate count of remaining capacity after being stored for some time after last use. With polarization effect this can only get worse.
LiPo batteries has a steep voltage drop after the platform voltage. Check this graph:

At 32min 35s, the battery had 3.6 volts.

After that, it drops extremely hard and fast and went down to 2.8 Volts only 3 minutes later.

What I did was just hovering the drone a feet above the ground to record this graph. No sudden moves.

With polarization your drone can magically get 0.1 volt or even higher after being stored for a day. However this voltage drops very quickly after being used again.
When you were having 3.6 volts and you stored your battery, next day you might see it starting at 3.7 volts.

And 3.7 volts means about 40% of battery left. 3.6 volts means about 10-14% battery left.

When you're going into sport mode, the drone consumes a very large current which can lead the voltage to jump even deeper.
It' s very common to store at 15% left, restart at 40% on screen, and then crash due to large amount of current causing extreme voltage drops.

FriedChicken_II Posted at 7-30 18:56
It's just an example. What I really meant is that your battery loses accurate count of remaining capacity after being stored for some time after last use. With polarization effect this can only get worse.
LiPo batteries has a steep voltage drop after the platform voltage. Check this graph:
[view_image]

Interesting to see this graph and other graphs that you have shown. Thank you very much for showing this and how  important this is to keep in your mind. I have learned a lot from your knowledge about lipo batteries. Many thanks again for showing this here to everybody.

FriedChicken_II Posted at 7-30 18:56
It's just an example. What I really meant is that your battery loses accurate count of remaining capacity after being stored for some time after last use. With polarization effect this can only get worse.
LiPo batteries has a steep voltage drop after the platform voltage. Check this graph:
[view_image]

And 3.7 volts means about 40% of battery left. 3.6 volts means about 10-14% battery left.

Totally wrong for MA2! MA2 has HV cells, makes forced landing at 3,65 V per cell (safe vallue) and after landing it shows 0% and refuses to start motors. Recharged cell has voltage of 4,35 V so 40% can be displayed at aprox. 3,9 Vots per cell on the groung without power load.
It is a big mistake to store battery with 15 % of charge and even bigger error is to try take-off with this battery. Like I said operator can estimate power left from average flight time and time spent in air during actual flight which is dispayed on screen. It is not good to rely on inaccurate percentage indicator.

The operator from the other thread made more errors:
- old batteries do not have performance of the new battery
- percentage indicator is not precise (can not be)
- take-off with 39% means that there's only about 1/10 of average flight time (for me with MA2 it would be 2-3 mins in calm weather conditions and N-mode)
- flying with old empty battery in S-mode

virtual Posted at 8-2 03:22
And 3.7 volts means about 40% of battery left. 3.6 volts means about 10-14% battery left.

Totally wrong for MA2! MA2 has HV cells, makes forced landing at 3,65 V per cell (safe vallue) and after landing it shows 0% and refuses to start motors. Recharged cell has voltage of 4,35 V so 40% can be displayed at aprox. 3,9 Vots per cell on the groung without power load.

My graph was cropped from an MA2 battery. But your points are right.