The batteries were always a temporary part of my Coffee In Coffee Out project. I wanted something else that would be better. And when I saw this inductive circuit on Adafruit, I knew what that better was.
Sadly the parts for this were sitting on my desk since the end of 2014. Things got all hung up on me over designing the way all of this would get mounted on the mug. Finally got over that. With a couple wooden stirring sticks, hot glue, and zip ties everything is go.
The 150mAh Lipo gives approximately 10 days of run time. So I may in the future someday look into using a super capacitor instead. But for now, this is good.