It’s unclear. I did a fresh install of Yosemite on a Retina MacBook Pro 13″ 11,1 but the battery life was terrible. Typically 4-5 hours max. In order to revert to the “Out of Box” state you need to delete the primary Mac OS partition and then boot to recovery using CMD + Option + R. This will initiate the “Internet Recovery” which will take hopefully less than an hour to download whatever OS the machine came with, in my case Mavericks. Upon receipt of the machine I did a fresh install of Yosemite but consistently saw terrible battery life. My hope was that it was Yosemite related, so I’ve reverted back to 10.9.4.
I’ve now performed an SMC reset and I see over 13:00 hours at 100% battery life under Mavericks. It’s unclear if Yosemite is at fault, or the SMC is at fault, the clean install is at fault, I mean who the fuck knows Apple? All I know is that I did a fresh install of Yosemite on a brand new machine and it got about 4 hours of battery life. Now it says it has 13 hours of battery life. Talk about a fucking unreliable narrator.