Battery Manager

BattMan Battery Manager is an easy to use widget to help you get the most out of your battery life. Simply add the one-cell widget to a home screen and BattMan lets you know how much time is left in your device’s battery. Touch the widget to open up a display of vital power information. You can also access all the device power settings right from BattMan.

Detailed guide:
http://www.curleysoft.com/BattMan/HowTo/index.html

Features:
•Estimates usage and charge times based on your use
•Displays status of Wifi, Bluetooth, GPS, NFC, Tethering and more
•Informs you of recent applications and screen settings

BattMan is ad free