iPhone 6(S)/Plus Iphone Battery problem

[NightMareKiller]

Hey, i have iphone 6 for a year and it starts to drain battery so i changed the battery with a new one but the problem of draining battery isn't solved. It keeps draining when the screen is off. Last night i charged it for a 100 percent and i woke up then i saw it like 20 percent

 

[now i see it]

Quit all apps. Put it in Airplane mode and set the battery setting to Low Power mode overnight and see if it's still draining fast