I had it even worse only 5 hours of battery life in my first week of usage. It turned out OneDrive had a bug with syncing; after reinstalling (then keeping it on overnight for the sync to finish), the battery jumped to ~8-10 hours with fairly heavy usage (Parallels + Safari, though with syncing paused), which is near your current level. The Energy tab of the Activity Monitor helped me identify OneDrive as the power suck.