I am really happy with my macbook, but apparently the update to El Capitán beta has ruined my battery definitely. I was really happy with battery life, whenever I used Safari with brightness at 50% my battery regularly lasted somewhere near 9 hours. Problems started when I updated to beta and after a few Cycles I saw a huge drop in battery life, because of this I decided to go back to Yosemite, thing is it didn't solve my problem. Now when I use my Macbook only with Safari open and brightness at 50% I am getting 5 hours tops, this is really frustrating as I have no idea of what to do to solve this problem. I've tried everything including resetting the DMC. Any ideas.