I have theory, but this is just theory.

Maybe in some conditions a FAN inside of Sparks is stopping then it lead to overheating and power cut off.

Is that possible to check in logs information about FAN and its RPM?

I saw a FAN may change speed or may stop. Maybe in some conditions a fan just stopping and then not starting when cooling is needed.

Could you chech in your logs more info about condition of fan just before cutting power off?

Its a good theory but i dont think there is any way to check .. maybe i should just pop the top off and fly around. It will def stay cool like that! Lol

You may try blocking the ventilation, do not fly, see if any message from Dji Go. I believe there will be some when overheat occurs.

In fact its good way to test. block vents, start engines, or hover few centimeters over soft pillow.

There is a risk - any overheating tests may cause damage - be aware of it before testing.

My inside fan make a lot of noise and sometimes go slower than it should, the fan have a problem (at least mine). Could be a reason, but another one was a suddenly stops when fly in sport mode than cause a very high inclination than stop motors. This happened me running in sport mode full forward and pressed the pause button, engines stoped and the spark crashed.

I put my Spark on desk then turned on. The fan was cooling at some rpm, then stopped, then started again. I am sure a fan is controlled.

I am not saying it is the issue, but it may be the issue.

DJI - please make a test, make a Spark hovering in hot place then get hot air and direct it on the Spark, and logg how a fan is working.
If you have some faulty example then better - do it on faulty unit, and then you will know its a matter of heat, matter or fan, or just a false clue.
If it will be NOT a matter of FAN, but a matter of heat, then you can test it is connected with battery or not.

Some spark felt even after two minutes of hovering - its not enough time rather to make things really hot, even if FAN will stop.
Honestly imo its rather a fault product line of batteries. Its the best way, because in that case only batteries should be replaced.

There is a folk in poland who is able to replicate the issue on his Spark with his battery. Two times his spark just felt after 2 minutes of hovering by some 'power cut off'.  I asked him to give a try on second battery.

It's possible to turn on a Spark battery whilst it's detached from the drone.. detach it, turn it on and hit it with a hair dryer and see if it shuts itself down. I believe the falling sparks (like mine) are dodgy battery related.

Kyokushin Posted at 2017-8-6 11:57
I put my Spark on desk then turned on. The fan was cooling at some rpm, then stopped, then started again. I am sure a fan is controlled.

I am not saying it is the issue, but it may be the issue.

I put my Spark on desk then turned on. The fan was cooling at some rpm, then stopped, then started again. I am sure a fan is controlled.

Mine does this also, I guess its normal.

How is your Spark doing since this thread?

DJI SPARK shows the warning message  ESC motors  overheated "" if the temp goes beyond 40 degree centigrade.
So don't worry too much. There are systems in place !!