You need to properly calibrate the battery. To do this go to the play store and download an app called "current widget". This is a widget that will tell you the physical mah values of your battery, in other words, how much juice you have left when your phone is not charging. Make a widget in your home screen and put the phone to charge, when its plugged in the widget will tell you how much mah of charge is needed to be 100 % full. Do not disconnect the phone when the led light turns green as it is not yet fully charged. You can see that when the light turns green that the mah values have not reached "0" So when the mah values reach to "0" or somewhere near 0 (<10), your phone is 100% charged. At this time, with the phone still plugged in go to the recovery menu or another app that can "wipe the battery stats" and reboot the phone. Your battery is now successfully calibrated and should fix your battery % issues.