I have the Iphone 6+ with a Speck gripper case. The stick-on metal piece fell off 3 times, so I superglued it to the back of the case. It did not seem to mess with the battery. For the few days it worked, it was OK if I had it on a vent fin that was vertical. I was not able to put it on a horizontal fin, because it just closed the vent. It slipped off the vertical fin several times, and when I tightened it further, the clamp cracked. Maybe you will have better luck.