Poor battery stats on rMBP late-2013 I unpacked my new MacBook only 2 days ago and it showed 9-10 hours of battery life (as advertised). I didn't calibrate it, since it is no longer necessary (I was told). 

Today I noticed that it started to show only 4 hours of battery life with 98% charge. I am a student and it shows me these stats when I run nothing - I am not editing photos, watching movies, etc. I only had I tab in a browser (Chrome) opened.

Do you know, why is that? Should I check with Apple if my battery is somehow faulty? 

I am a first time MacBook owner.
Check the Energy tab of Activity Monitor and look for processes that have a high energy usage.



Screenshot Source
Leave it for a bit longer (up to a week) to see if there's any change.