Wrong. In the last week or so, both Apple and Google have confirmed that closing your apps does absolutely nothing to improve your battery life. In fact, says Hiroshi Lockheimer, the VP of Engineering for Android, it might make things worse.
@pierce @mcwm @MarcusDPK @qz could very slightly worsen unless you and algorithm are ONE (you kill something, system wants it back etc)
— Hiroshi Lockheimer (@lockheimer) March 14, 2016
Really that’s all you need to know. You can stop here. This isn’t even particularly revealing, really; it’s just nice to hear the people who built the platforms confirm it. Here’s the takeaway, once again: Stop closing your apps, because it’s not doing you any good. But if you want to know why, it helps to have a basic understanding of how multitasking works.
On iOS, for instance, there are five different states an app can be in at any given time. (Android’s setup is similar enough that we don’t need to go over both.) Not Running is obvious: You haven’t launched it, it’s not running. Active is up on the screen and doing stuff. Inactive is a transitional phase, where it’s on the screen but not doing anything as you switch to something else. Background is when the app isn’t in front of your face but is working, refreshing your emails or bringing in the latest fire tweets. Last, there’s Suspended, which is when an app is in the background and doing absolutely nothing. It just sits in memory like a bump on a log.
On both Android and iOS, algorithms run memory management. They’ll close apps that need to be closed, typically ones that have been dormant for a while or are using more power or memory than they should. And they’re very good at knowing when you’re going to need data, or want a refresh, or open an app again. Apps that are already in memory open quickly, rather than having to fully start again; it’s like waking your computer from sleep rather than rebooting it completely. You’re far, far better off letting the system work for you rather than forcing it to re-open and re-start everything every time. Battery questions aside, it makes your phone slower and less coherent.
If you’re into saving battery, there are lots of things you can do. Turn down screen brightness. Turn off background refresh for apps. Use Low Power Mode in iOS, or enable Doze on Android. Turn off location sharing for apps that don’t need it (which is a good idea regardless). Put the whole thing in Airplane Mode, if you’re feeling really crazy. But stop swiping your apps out of view, because it’s not helping. If anything, it’s making it worse.