Hi Mike - thank you very much for taking the time!
Thats a nice way of plotting key metrics from the log - what tool is that?
Your conclusion seems logical however - I ran a new test today with a fully charged battery and the issue happened almost right away after starting a very minimalistic mission - it didn't even get to land before it happened.
I was again able to regain control and I learned that if i tried gentle corrects to get the quad back to my landing zone, the quad would kind of fight me, and continue the big bowling motion - but if I did some very harsh corrections (hard left, hard right, hard foreward and hard backward) the quad would eventually come back to it's good old self. I then had it hovering gently for almost 7 minutes without any problems and with juice left on the battery.
When I tried to recover the logfile, something went wrong (got a corrupted message) - in essence, I couldn't recover the file....
I'll try again tomorrow. I'm suspecting a brownout maybe? Will try a different power module for the APM.