terminal from the charging discharging device or the main unit of the equipment application_number US 90373597 A description an embodiment of the present invention is described below with reference to the drawings fig1 is a view showing the layout of a portable telephone terminal including a battery pack constituting an embodiment of the present invention in fig1 battery pack 10 is installed as a part of portable telephone terminal 20 this battery pack 10 is constructed so as to be capable of being attached and released from the main unit of portable telephone terminal 20 in the condition in which battery pack 10 is mounted in the main unit of portable telephone terminal 20 shown in fig1 battery pack 10 is connected to power source circuit 21 within portable telephone terminal 20 by means of terminals cc1a cc1b and terminals cc2a cc2b power source circuit 21 within the main unit of portable telephone terminal 20 then uses the dc power source of battery pack 10 supplied from terminals cc1b cc2b to generate and supply the power source voltages and currents needed for operation of the various units not shown of the main unit of portable telephone terminal 20 also battery pack 10 is connected when charging discharging is required to a charging discharging device 30 to be described through.