Why my bettery dies at 50%

[ateenyikeny]

I have owned my Xperia z1compact for one year and everything about it was good. Though from no where am experiencing problems with my battery. the phone goes of at 50% and takes long when charging.
I upgraded to android 5.1.1
Which is good... Any help

 

[B. Diddy]

Welcome to Android Central! Moved to the Z1 Compact forum. Did you upgrade to 5.1.1 using the official over-the-air update?

Did this battery issue start suddenly? If so, was it right after the update? The battery might simply be failing, and may need to be replaced.