R 11 battery stuck at 8%

My R 11 stays plugged in most of the time so I unplugged it to "exercise" the battery to make it last longer. I didn't plug it back in before the battery discharged to the point the machine shut itself off and this happened a few times now. It has always charged pretty quickly but now it's stuck at 8% and seems to have stopped charging unless the reading is incorrect. For hours now it says 8% and the time until charged is gone. When unplugged it says 0:51 left. The machine is fairly new so I doubt the battery is bad and guess it needs to be reset or has a loose connection, though I've never bumped or dropped it. Any ideas to try? I don't see how to reset the battery.