Abstract: The battery charging system allows a power consumption of an information processing apparatus to be maximally reduced when the system is off. When a charge request signal is output from a microprocessor of one battery, a connection control circuit puts one switch circuit into a open state and the other switch circuit into a closed state. As a result, a Smart Selector operates to start charging the battery whose connection has been detected. When the battery is fully charged and a full charge signal which is an inverted version of a charge request signal is output from the microprocessor, the connection control circuit operate to open the closed switch circuit and to close the opened switch circuit. The Smart Selector is made to recognize that the battery is no longer connected and detects only the other battery, thereby beginning charging to the other battery.

Abstract: In order to reduce power consumption of the electronic device while it is inactive, the main switch 32 is shifted to the non-conductive state when the electronic device driven by the battery is stopped and the actuating signal decreases below a predetermined voltage, the actuating signal representing the state where the device is in operation. Thus, the power supplied to the control circuit or the like of the electronic device from the battery becomes zero, should a leak current or the like is ignored, and the power consumption can be reduced. In order to start the electronic device, the switch 34 is turned on and the main switch 32 is forced to the conductive state. That is, when the electronic device is started and the actuating signal exceeds the predetermined voltage, the main switch 32 becomes conductive and the electronic device receives power from the battery. In this state, even if the switch 34 is opened, the main switch 32 still remains conductive unless the actuating signal is stopped.