Share your experience!
Were you able to fix your other issue?
http://talk.sonymobile.com/t5/Xperia-Z3/Xperia-Z3-plus-turns-off-at-50-battery/m-p/1171799#M3968
you probably need a new battery for your Xperia Z
It's really hard to say what's wrong with it, you will have to get it inspected.