Hi, I just got my brand new rMBP and I love it, replaced my old machine. It is a screamer but the batter life is disappointing. One of the reason I got it in the first place was the "up to 8 hours" battery life but I it is more of a 3 hours battery life. I do understand it might not be always 8 hours and it battery life depends but I am 3 is nowhere near 8. I am on a 4th cycle at the moment, brightness about 2/6, no video, no music, just browsing the web. Is that normal? What shell I do?