Even if you're a task-killing ninja, there are still plenty of apps that somehow bite into your battery life. And that problem can be even worse when your phone is asleep, when you can't even tell which apps are being battery hogs. A new tool called Hush, which was developed by Purdue researchers, aims to solve that dilemma for Android phones by intelligently stopping apps that run in the background while your phone is asleep. It prioritizes the apps you use a lot and stops apps that you rarely use from gumming up the works. Researchers say it can save around 16 percent of battery life -- that's not huge, but it could be very useful if a similar tool were embedded with phones. You can test out Hush for yourself via its Github page, but it'll likely be a while before it's available in a more polished form.