A battery pack, comprising: a battery module having a positive electrode terminal and a negative electrode terminal; a first power connector having a first power terminal connected to the positive electrode terminal, a second power terminal connected to the negative electrode terminal and a first auxiliary terminal (Pa), the first power connector being configured to be coupled to or separated from a second power connector that is included in an external device to receive an electric power of the battery module; a control unit configured to determine whether the first power connector and the second power connector are coupled; a first communication connector configured to input or output a communication signal between the external device and the control unit; and a communication switching unit installed between the control unit and the first communication connector, a first resistor element having a first end electrically connected to the ground and a second end electrically connected to the first auxiliary terminal (Pa); wherein the control unit includes: a sub-control module configured to determine that the first power connector and the second power connector are coupled when a voltage applied between the first end and the second end of the first resistor element is included in a threshold range, and then supply an operation power; and a main control module configured to shift from a sleep state to a wake-up state when the operation power is supplied from the sub-control module, and the main control module is configured to turn on the communication switching unit when operating in the wake-up state; or when the voltage applied between the first end and the second end of the first resistor element deviates from the threshold range while the main control module is operating in the wake-up state, the main control module is configured to determine that the first power connector and the second power connector are separated, and shifts from the wake-up state to the sleep state, and the main control module is configured to turn off the communication switching unit when operating in the sleep state. a battery module having a positive electrode terminal and a negative electrode terminal; a first power connector having a first power terminal connected to the positive electrode terminal, a second power terminal connected to the negative electrode terminal and a first auxiliary terminal (Pa), the first power connector being configured to be coupled to or separated from a second power connector that is included in an external device to receive an electric power of the battery module; a control unit configured to determine whether the first power connector and the second power connector are coupled; a first communication connector configured to input or output a communication signal between the external device and the control unit; and a communication switching unit installed between the control unit and the first communication connector, a first resistor element having a first end electrically connected to the ground and a second end electrically connected to the first auxiliary terminal (Pa); a sub-control module configured to determine that the first power connector and the second power connector are coupled when a voltage applied between the first end and the second end of the first resistor element is included in a threshold range, and then supply an operation power; and a main control module configured to shift from a sleep state to a wake-up state when the operation power is supplied from the sub-control module, and the main control module is configured to turn on the communication switching unit when operating in the wake-up state; or