A power supply interface system for a medical device may include a battery compartment and a battery interlocking system. The battery compartment may define at least a first battery area and a second battery area, the first battery area configured to receive a first battery and the second battery area configured to receive a second battery. The battery interlocking system may include a first interlock mechanism including a first locking portion and a first selector. The first locking portion may be configured to move between a locking position and a non-locking position, the locking position substantially preventing removal of the first battery from the first battery area, and the non-locking position not preventing removal of the first battery from the first battery area. The first selector may be configured to move the first locking portion from the locking position to the non-locking position in response to the second battery being received in the second battery area.