Your iPhone's battery life is going to get a lot better soon

Will Wei/Business Insider

There's a good reason to upgrade to iOS 9, the latest version of Apple's mobile operating system, which came out on Wednesday: longer battery life.

Apple says that iOS 9 will give your iPhone an extra hour of battery life. The new operating system is more efficient overall, so it won't drain your battery as quickly as before.

It has some neat battery-saving tricks — it uses sensors in your phone to recognize when it's face down on a table, so your phone won't light up with notifications (text messages, tweets, and the like) when nobody will see them.

Apple says you'll get an extra hour of battery life with the new operating system, but the Wall Street Journal's Joanna Stern found that it's closer to 40 minutes.

Still, that's better than nothing! 

—Joanna Stern (@JoannaStern) September 15, 2015

There's also a new setting, appropriately named named Low Power mode, that you can turn on when you're in a bind. This reduces the brightness of the screen and prevents the phone from doing certain things, like running apps in the background, that can take up power. You shouldn't use this setting unless you're worried you'll be away from a charger, as you won't get the most out of your phone.

You'll get a notification to turn on Low Power Mode when your phone's charge hits 20%.

Taking advantage of Low Power mode is easy. First, tap the Settings icon on your phone. Then, tap the Battery icon. 

Screenshot/Tech Insider

There, you'll see the setting for Low Power Mode.

Screenshot/Tech Insider

Tap the switch to turn on the energy-saving mode.

Screenshot/Tech Insider

Again, you should only use Low Power Mode when you're in a pinch. Stern, who conducted tests on different phones running the new operating system, found that leaving Low Power Mode on all day gives you an extra 3.5 hours of battery life, but the brightness of the screen is so low that it makes using your phone a drag.