You can save additional hour of your battery life if iPhone is facedown. However, you will need iOS 9 or higher to get this feature. This feature will turn off the screen when you get notifications, which in turn helps in improving battery life.
This feature is only available on the iPhone 5s, iPhone 6 and above. If you have iPhone 4, 4s or even 5c, facedown feature won’t work.
I use this feature when I do have less battery and am not able to charge my iPhone. This works like a charm. Try it. It might be very helpful.
If you want to increase battery life, please Click Here.