I have Lenovo P780. At first the battery with 4000 mAh is very good. It could stand for more than 40 hours. Then after upgrade the Android and install many application such as Battery Saver etc, the Battery only last for 20 hours only.
Then somehow I format my HP by clear the EMC. Then reinstall the Android. The battery is as good as new. It could last 40 hours again. But the GPS not working though it's already active and all the application that use GPS has access location.
I've try anything but it doesn't solve the problem.
Then there is a menu that we could move it up and down using Max or Min Volume. Choose "Clear EMC". After that, reinstall the Android again, then the problem is solved. The GPS is working now.