The problem is MTP mode! it doesnt allow copying incomplete or corrupt files. Just copy that file in Mass transfer mode. You can use a card reader for external SD cards or mounting in recovery for internal SD.
Mine is always above 90% and with that i get 4hrs battery life.I also tried an extended battery od 3500 mhA and it did 7-8 hrs but phone feels like a huge rock!So damn thick,not logical.
Right now its 98%...Wil try to post a screenie