Yesterday while hovering at about 8 ft from the ground and 10 ft from me, my PV2+ suddenly without warning accelerated vertically upward at the maximum speed. I had no control of the Phantom. It did not respond to any stick action. It hit the top branches of a lodge pole pine (about 80 ft up) then fell to the ground. It all happened in a couple of seconds. One critical bit of information I noticed: as it was rising, all Phantom lights were solid red. That indicated an error occurred. Bringing it inside, I checked it out with the Phantom assistant, and everything reported normal condition, except the battery showed 7% charge. I have the warning set at 20%. There was no low voltage warning before the crash. One other fact to consider, several months ago the copter made an emergency landing, the controller giving the the low battery alarm, showing the battery voltage dropping suddenly from a 40% charge to 5%. Lucky it landed in the middle of a soybean field and there was no damage. In that case, the copter was too far away for me to see it or the lights. I was using this same battery yesterday. Gonna throw that battery away! Many other crashes folks have experienced could be the result of a bad battery. I'm very lucky that the copter fell landing on its rear left arm and will require a new shell. All motors and controls checked out and work fine, The camera received no damage!