So I got my MacBook in the summer of 11, instantly put OSX 10.7 on it, got easily 7 hours of battery out of it with Mail, Safari, iTunes, Calendar, and a few other things running in the background. Skipped Mountain Lion and upgraded straight to Mavericks earlier this year and my battery instantly got slashed to 4 hours. I just lived with it since I figured maybe it was an old battery. Upgraded to Yosemite last week and decided to dig into this battery issue. My cycle count is just over 300, well within healthy spec. So I disabled a whole bunch of features I don't need, uninstalled any unnecessary software, rebooted in Safe Mode, rebooted into normal mode and ran the battery until empty and it shut itself down. Restarted. 8 HOURS REMAINING! That's more like it! I thought maybe the battery needed calibrating so I used it for a few hours and plugged it in to charge overnight. IT'S BACK TO 4 HOURS!! I said "heck with this" and wiped the hard drive, reinstalled OSX 10.10 and checked the battery with a full charge and a brand new system. Says I have 9 hours remaining. Ok, that's impressive. Maybe I had a bad preference file or something in there leftover from my OS upgrades. So I spent all night copying over JUST my files (documents, music and pictures, 188GB free on my 320GB drive) and Call of Duty and YNAB. I enabled iCloud and Gmail in internet accounts and installed Dropbox and Caffeine. That's it. Other than exactly what I stated my system is completely fresh. IT'S BACK TO 4 HOURS!! GAAAAAAH! I quit Dropbox and Caffeine, disabled the iCloud and Gmail internet accounts, shut off Spotlight indexing and that still didn't fix it! HOW DO I GET MY 8-9 HOURS?! I seriously do not understand. It seems as if merely having data on the hard drive causes the battery to drain. The only other thing it could possibly be is a background process that comes with Dropbox that has been screwing me over since May this year. Which is bad, I need Dropbox. Any and all help is appreciated before I have a heart attack.