Battery life, it’s the bane of every iPhone user’s existence, right? It’s hard to tell, really, reading the internet, which specific steps to take to make sure your battery is working at its most efficient, giving you the longest life without compromising performance.
One of the most misunderstood areas of managing battery life may just be the brightness settings. Here’s what Apple has to say about it.
Dimming your iPhone screen is an obvious way to use less power on your iPhone. If you’re running iOS 5.0 or later, Apple recommends dimming the screen by heading into your Settings app. Tap into Brightness & Wallpaper, and drag the slider to the left until it’s as dim as possible, while still letting you see enough of what’s on the screen o do what you need to.
In addition, Apple says that turning on Auto-Brightness allows your iPhone (or iPad) screen to adjust to the ambient light, keeping the iPhone screen to the lowest brightness (as defined by where you set the slider) possible in dimmer light, saving you precious battery power.
To turn Auto-Brightness on, tap into the Settings app, then tap Brightness & Wallpaper. Tap the Auto-Brightness toggle to ON, and then hit the Home button to get back to your iOS device’s home screen.
Source: Apple Support