I recently purchased an iRobot Create2 and have had a lot of issues in the last few weeks with the battery being dead when I go to use it. The robot almost never leaves its charger at this time because I am still working on coding it. This makes me wonder if there is a state I could be leaving the robot in that is preventing it from charging. The only way I can get it to charge is to do a hard reset which then allows it to start charging. My suspicion is that if you put it in full mode and disconnect from it that it can not charge. Can anyone confirm or deny this?
See page 4 create_2_Open_Interface_Spec.pdf
In Passive mode, Roomba will sleep after 5 minutes of inactivity to preserve battery power. In Safe and Full modes, Roomba will never sleep, and if left in this state for an extended period of time, will deeply discharge its battery, even if plugged into the charger. The charger will power Roomba in all modes, but it will not charge the battery in Safe or Full mode. It is important that when you are finished working with Roomba that you issue either the Passive or Stop command to protect the battery.
While the Roomba is charging in a trickle mode it will only supply enough power for its internal circuity. If your controller is using power from the min-din the battery will run down as its supplying the extra power. You can confirm this by using the OI to note the "-" sign on the charge current during Passive mode trickle charging