PURPOSE: To automatically stop the charge by connecting a plurality of batteries to a multiplexer and a microprocessor through a control circuit, and computing the voltage difference between the batteries with the microprocessor, and arranging it over scheduled value. CONSTITUTION: A multiplexer 28 is connected to power output through a resistor 30, and it is connected to each battery A-D through control circuits 42, 44, 46, and 48. The microprocessor 66 indicates the charge condition of light emitting diodes 78, 80, 82, and 84, and computes the voltage difference between the batteries A-D, and automatically stops the charge by the voltage difference getting over the scheduled minimum storage value. COPYRIGHT: (C)1990,JPO