I was testing out my new Phantom which I upgraded to 3.0. I started the Phantom in on location letting it idle and than walked to another location that had enough clearance from trees to test to see how well it would hover. After that test, I walked another 50 yards or so out into a field & proceeded to do more test flying. After a short time the Phantom started heading back towards where I did the first hover test. I lost complete control of it. I ran following to see where it was going and it flew right past the area where I did the hover test into a tree and feel straight down to the ground. It was upside down on resting on the props when I got to it. After falling about 15' to 20', the only damage I found was the Zenmuse 3D H3 mount got bent and something shifted to where the yaw gimbal couldn't turn freely. After I thought about it, it was my fault that I started to do the last test when the battery was down below 50%. I guess it was trying to fly home but not sure where home was really established. From now on, I will (1.) make sure I have a full battery charge before I fly and (2.) I know where home is and make sure it is a place the Phantom can make it back to without going through trees or other things like power lines. My question is and I'm sorry if the subject has been discussed, what establishes where home is when flying the Phantom?