The present application relates to a battery box, the battery box comprising: a charging and energy storage unit for charging and storing electrical energy using an input voltage supplied to the battery box; a power failure detection unit for detecting a power failure of the input voltage; and a power output switching unit for switching an output based on a detection result of the power failure detection unit, wherein the power output switching unit is configured to output a voltage from the charging and energy storage unit when the power failure detection unit detects a power failure, and is configured not to output the voltage when the power failure detection unit does not detect the power failure. The present application also relates to an air conditioning system and a control method for the air conditioning system.