I had a problem with my 2. It was media server running. Check your running apps, is media server the top consummation of battery time? You can kill it; but it will start again. Even clearing its cache file did nothing. My fix was to format my Sd card after backing up my files, thank god the 2 has OTG. Then I rebooted to book screen (hold power and volume down, be aware boot loader appears guickly) go to format the cache partition. That solved the issue.