Greenify (free)

Getting the most from your phone’s battery is always key. Lollipop may have its own set of battery-saving tools, and many phones now offer power-saving modes, but these should be seen as a last resort. Greenify will help to optimise your phone’s battery.

Greenify sits in the background helping to regulate how much battery various apps are using. It freezes the apps you tell it to when you’re not using them, and instantly defrosts them when you need to gain access.
The app no longer requires root access on your Android device, meaning it’s perfect for anyone looking to save power.