Flying my p2v + today to bring battery level down to 8% so I could do the 20 cycle recharge. 1st battery had no issues.Flew it to 20% level then hovered till 15% and then landed.I then restarted the motors and kept then on until 8%. Powered off and put 2nd battery in and repeated the same procedure. This time as I was hovering at about 6 ft agl and with 21% battery left the quad just fell straight down and landed as if it lost power but it landed perfectly with the motors still running and battery at 21%. I had satellite lock and was in gps mode hovering near my home point.I was using the litchi app on a android phone. I have the flight logs but I'm not sure which log corresponds with this flight.If anyone could tell me what log item to look at that would be great. Thanks!