PURPOSE: To discriminate batteries by capacities and the individual management of batteries of the same capacity by providing an ID signal generator.

CONSTITUTION: A sensor 1 detects that an Nicd battery using apparatus or a battery charger is connected to an Nicd battery charger pack. A controller 2 reads the setting condition of a DIP switch 3 to set the ID number according to the above detection, and outputs it to the apparatus using Nicd battery and to the battery charger as a serial signal. As a result, the discrimination by the capacity of the Nicd battery, or the individual management of batteries of the same capacity can be carried out.