Chios, If your battery drain quickly after replacement then there most probably you have installed any third party battery in your system mostly these local batteries doesn’t work properly. If this is not the case then there maybe any software related issue in your phone.
[link|https://okadtech.com/iphone-6-battery-draining-fast-suddenly-iphone-6-battery-problem/|How to fix iphone battery draining fast problem|new_window=true]
I can refer you this article this will help you in solving the software related issues which is draining your phone battery you can use these in android system too.