My Robot Runs On Coffee

Kid Analog built a robot to work at the coffeeshop while Kid went on tour with his music.  The robot uses Coffee to refuel.  How does this work?

The Bot flushes out electrolyte that has no more electricity in it.  Then it recharges by drinking coffee, then using the electrolytic composition in coffee to continue to run.  Kid Analog wanted to select a power source for the Bot that was both cheap, and abundantly available.  Coffee seemed like the best alternative.