Welcome to Android Central! It would be helpful to see some battery stats. Charge up to 100%, then let it drain to 20-30% with normal usage, without charging in between. Then show us:
1. The main
Settings>Battery screen.
2. The fullscreen battery graph screen (which shows Awake time and Cell Signal Strength).
3. The Screen category (to see total Screen On time).
4. The Cell Standby category, if present (to see Time Without Signal).
http://forums.androidcentral.com/ge...ide-how-post-screenshots-android-central.html
You might have to install a 3rd party battery monitor, like GSam Battery Monitor, to get the Cell Signal Strength graph.
One easy thing to do after updates is to wipe the cache partition, which can sometimes help with general issues like this:
https://support.t-mobile.com/docs/DOC-21095