Fast discharging, poor battery life - warm above Sim Tray
I'd like to ask You for Your help. I came across dead iPhone 5S, so I swapped battery for a new one and It came allive. But I ran into a problem and that's poor battery life. Any idea what could cause fast battery discharge? (With everything turned off, even SIM it takes only around 10h to be fully discharged.) Otherwise everything works, sim, bluetooth, wifi, sensors, camera everything OK. I looked for a possible answer the most probable would be the U2 ic chip, but I don't have anny other issues than just poor battery life. It connects to PC OK, I even tried to delete and restore It as a new Phone and downloaded a fresh SW from iTunes and installed it and it is OK, charging is also OK(Even from a dead battery.) I also noticed that the place above Sim tray is always a bit warm(barrely noticeable(NOT hot) when I compare It to my iPhone 5 - that one is stone cold at that place, when just sitting on the table.)
Any Idea what could it be?
Or could this make cheap bad new battery?
Is it normal that iPhone 5S is warm above Sim tray all the time compared to iPhone 5?
Is this a good question?