5s horrible Battery drain, tried all IOS7 tips and new Batteries!

Hi there!

So, i traded my 5 for a 5s with shattered screen. Seemed like a good deal at the time, by now i regret it.

I ordered a new display unit and used it until i got the screen.

I noticed the battery going down way quicker compared to my 5. And when it reached like 30% it shut off as i tried to open an app, over and over again.

So i went and bought a new battery as well, changed it out as i changed the screen. Changed some screens before on 4 and 4s also a few 5, so not the first time.

Screen is not fixed, the battery problem stayed, it drains the battery super fast but doesn't shuts off like it did with the old battery.

Tired all the steps they're saying about settings etc pp, my Standby and Usage times are right and not the same.

For example, 1h52 usage and 4h13 Standby -> 34%

2h43 usage and 6h36 Standby-> 2%

So i thought i got a !@#$%^ battery, bought another one. Still the same :(

I'm not sure what to do, if i send it i might end up paying, but the way it is now is a pita.

Anyone has an idea what it might be?

Thanks a lot!