[Q] [Help] Battery Drops to 1% from 20%[KK ST18i] topic

My Xperia Ray Running on Kitkat 4.4.4 is facing a sudden battery drain. When the battery is about 20-25%, It suddenly drops down to 1%. :crying:
Is there any method to solve this?
I had tried flashing the ICS firmware. and again flashing the Kitkat Kernel. This did not fix the issue.
Can anyone suggest a fix for this?