How can I make a safe Ni-MH charging station?
Add connector for thermoresistor into charger dock.
Make thermoresistor go into contact with batteries when gobot goes to dock.
Install charger circuit into robot, not dock (by Dave Tweed).
Use delta-V charger (by Ignacio Vazquez-Abrams).
Use timed charger (require fully discharged battery).
Use slow (0.1C 10 hour) charger.