The described technology relates to a battery pack and a data transmission method for the battery pack. In one embodiment, the battery pack includes a battery comprising at least one battery cell and a controller configured to check a state of the battery and generate a battery state signal corresponding to the state of the battery. The battery pack also includes a switch circuit configured to operate based on the battery state signal and a resistor circuit configured to be electrically connected to a reference node through the switch circuit. The switch circuit is configured to make or break electrical connection between the resistor circuit and the reference node based on the battery state signal.