Whenever I review a phone, one of the first things I do after setting it up is charge it to full and then just… let it run, using it as my only phone for as long as I can, resisting every urge to charge it along the way. The Oppo Find X9 Pro lasted for three full days. 74 and a half hours, to be a little more exact. I couldn’t quite believe it either, so I ran it again. This time I turned on the power-hungry always-on display, and the phone ran for 50-odd hours before the battery hit low single