7 month old 13" i5 8 GB RAM MBA and 58 cycles When I open up Safari and browse through webpages (not heavy) it shows my battery life as 5:42 left. I am on a little less than 50% brightness and only have 3 tabs open. As for other apps I have mail, twitter, skype, last.fm open but not being used. Watching youtube videos will drop that time to like 3-3.5 hours after only 20 minutes of use This seems very poor considering the low usage. When I check activity monitor nothing has high CPU usage though. I used to get around 7.5-8 hours a few months ago so what could be causing this? It seems like the battery life that Apple advertises is based on you not using the machine at all and just let it sit on the desktop. If I do that then it shows closer to 7-7.5 hrs.