Primarily what is DU Battery Saver ? 

The world's outstanding battery saver and Android power doctor & manager, This is a FREE battery saving app that form your battery last longer.

Installing DU Battery Saver takes us to a screen where we're presented with details about our phone's battery, including its temperature, voltage, and charge level. Also, the app provides an intelligent estimate as to how much time we have left until our battery dies, based on our current settings and usage pattern. 

 Mainframe it afford for your device is feasible, and organized in such a way where you will not be screaming at your device because you can’t find a certain feature you want to use. One of the biggest objections that have plagued the Android OS is the fact that you technically can’t close an app after using it, unless the app gives you the option, or you go into your application’s settings to force the app to stop. Of course Android has gotten better at closing your background apps, but there are still going to be some apps that will still be remain running. DU Battery Saver makes it easy to optimize your battery, but allowing to just touch your thumb to your screen and bam, background apps are closed and your battery’s life gets extended.

DU Battery Saver also has other features that may seem whimsical and some that are probably useful, if you can find a purpose for them. For example, you can choose a battery skin, but don't expect it to change how the entire app looks. It really only changes how the battery image is shown. There is also a Messages feature, for messages that DU Battery Saver will send you. That's where notifications from the app are shown.

it comes with four battery saver modes, i.e., Prolong, General, Sleep and My mode. All the saver modes come with six features Screen brightness, screen timeout, Vibrate, Wi-Fi, Bluetooth, Sync, Haptic Feedback. These features can be customized in the My mode option. You can add an extra mode by tapping on Add a mode in the same window where you can manually set the above six features to that mode and can name the mode for further use.

The application itself is useful and shows the battery percentage in the notification panel. There are some widgets available in the widget section and can be placed on the home screens, to get a quick view about the stats and estimate battery life. Four different widgets, each having unique roles, are available. Of them, the 4×1 is something you should consider using, as it shows the time left for the battery to get down to zero. The other widget options are connectivity notifier, and also a button to Optimize and kill the apps that are draining the battery.