You have to be careful to not let your lipo drop below 9V. It will be damaged. A lipo alarm would be a good idea. I made one from a couple transistors, resistors, and an LED. Also, hopefully you have upgraded to the 9tooth motor. If you don't like the bursting of the tail motor, turn down the gain a little on your gyro. I also have the drop for no reason problem. I don't know what is happening yet. Horizon said to send the 4 in 1 in for testing. I don't want to part with it for that long. The problem went away for a while, but now it is back. Hopefully it will go away again. Since I am only hovering still, it isn't too critical.