Have the same issue, the computer is roughly 28 days long, horrible battery life, around 2-3 hours while reading on safari reader view, constantly checking. with Activity Monitor, there are no apps that are using significant power.
And 2 days ago started the second act of the issue, I discovered that the computer thinks it is plugged in even it isn't! It has been showing "not charging" on the battery menulet for the last 2 days. The issue isn't resolved with an ordinary restart, an SMC or PRAM reset looks like a solution for up to 2 hours then it is back.
And now for the last hour, while it is not plugged in, it shows "charged" with a thunderbolt on the battery icon on the menulet, where as iStatPro shows "charging" with 96% battery, on the other hand Coconut Battery shows "Connected" with 89% battery. Go figure! The **** machine and the battery is just 28 days old!
I would advice everybody on this thread to check if their machines think they are plugged in and since I do not expect Apple to figure out the problem soon hope anybody here stumbles upon one.
Cheers