Matt Birchler has asked the question I imagined many would come to ask after the launch of iOS 9:
One of my favorite new features of Apple’s iOS 9 is Low Power Mode. This feature is designed to kick in when you reach 20% battery remaining, and give you a little more time before you have to race to a charger. And while most iOS 9 reviews covered this mode briefly and determined it worked as advertised, I wondered what would happen if you used Low Power Mode all the time. I was surprised that no reviewer seems to have done this, so I took it upon myself to give it a try. I don’t have any standardized battery tests that I can do, so I simply spent the last 2 weeks alternating between using Low Power Mode all day, and not using it at all and comparing the differences. My findings are rather remarkable.
As I explained, I advise against leaving Low Power Mode enabled all the time because it’ll alter your iPhone experience across system apps and third-party ones. Still, fascinating findings with impressive results.