There are lots of diagnostic reports that are run in beta versions. On the latest beta of 10.11, I easily get 8-9 hours battery life with brightness set to the

There are lots of diagnostic reports that are run in beta versions. On the latest beta of 10.11, I easily get 8-9 hours battery life with brightness set to the middle with Safari, iTerm, Mail and iTunes running. Are you using Chrome/flash at all?