Battery life has been consistently at 8/9 hours at 100% charge until I installed 10.11.6. Now it is at best 4 to 5 hours. I've tried resetting everything and a re-install of os x but nothing seems to work. No apps are showing significant energy except safari (as I type this post). I've also lost 2% battery charge in under 10 minutes. Any suggestions, am I alone with this issue?