For our charging station to pass the California Energy Commission certifications, there is a built in timeout that limits charging sessions to 4 hours.
To put it plainly, the moment you place your Misty II on the charging station a timer begins and will stop charging after 4 hours. You can reset this timer by either unplugging the charging station, or lifting Misty off the base station for a few seconds (we recommend 10 seconds just to be safe).
We’re working on a software fix to ensure your robot will not begin this timeout if the robot is powered on. For today, if you notice your robot not charging, just lift you robot off the base station for 10 second and put it back on!