Apple is introducing a couple new features in iOS 9 to help extend the battery life of your iOS device.
The first feature is one you'd likely never know was present unless told otherwise. Any time you place your iPhone face down on a surface, be it a desk or a bed, it's able to detect its orientation. As such, the screen will forgo lighting up when it receives a push notification.
Place your iPhone face up on a surface, and it'll continue to light up as it always has.
The second feature is what Apple is calling Low Power Mode. When enabled, the low-power mode will modify the amount of energy it dedicates to background services and animations (among other things). In other words, features such as background app refresh, and push email will be temporarily paused until you've had a chance to charge your device.
When your iOS device reaches 20 percent battery, you're automatically prompted to enable low-power mode. As you can see from the prompt above, you're reminded what will happen to your device each time you enable the feature.
You'll know low-power mode is enabled by looking at the battery icon in the upper-right corner. The battery will transform to a yellow icon, instead of the typical red when under 20 percent. Another quick indicator is the added battery percentage next to the now-yellow icon.
Once you charge your device past the 20 percent point, the energy saving feature will turn itself off without any further action needed on your part.
For those times when you want to save battery well before hitting the 20 percent mark, you can enable it manually.
Launch the Settings app then scroll down to the new Battery item; tap on it.
Slide the switch atop the screen to the On position to enable Low Power Mode.
As found in iOS 8, iOS 9 also includes a list of apps and their respective drain on your battery. Only now the list clarifies if battery usage is caused by background tasks, the screen being on or other miscellaneous uses.
All in all, Low Power Mode is said to add an extra hour of battery life to a device after it hits the 20 percent threshold.