Patent ID: 7864065

Claim:
A battery pack detachably connectable to an equipment body to supply power to the equipment body, the battery pack comprising: a battery cell; a microcomputer configured to communicate with the equipment body; a connection terminal connected to the microcomputer; a positive power supply input terminal connected to a cathode of the battery cell; and a negative power supply input terminal connected to an anode of the battery cell, wherein, after the power of the equipment body is turned on, the microcomputer is configured to alternately send to the equipment body by serial communication via the connection terminal information to be used in authentication processing executed by the equipment body and information to be used in a battery residual quantity count executed by the equipment body, the microcomputer is configured to repeat alternately sending to the equipment body the information for authentication processing and the information to be used in the battery residual quantity count a plurality of times, and after the authentication processing is complete, the microcomputer is configured to send to the equipment body information to be used in updating the battery residual quantity count executed by the equipment body.