PURPOSE: To improve the working ratio of the load by canceling a discharge inhibition state to restart discharge when a current supplied from a d.c. power supply is detected even after the terminal voltage of a storage battery has dropped to the predetermined level of discharge inhibition.
CONSTITUTION: A current from a d.c. power supply with unstable output (e.g. a solar cell 1) flows through a reverse blocking diode 2 and a CT 10, together with the output of a storage battery 4, to a load 6. The passage of the current is made or broken by means of a switch 5. A charge/discharge control unit 13 outputs a load connection control signal 9 according to the input signals from the CT 10 and a storage battery voltage detection unit 8, and thereby opens or closes the switch 5. When the output of the solar cell 1 is reduced and the output voltage of the storage battery 4 drops to a specified value, a load connection control signal 9 opens the switch 5 to bring the system into the discharge inhibition state. When the CT 10 thereafter detects a current from the solar cell 1 having a specified value of above, a charge/discharge controller 3 closes the switch 5 to restart discharge even if the terminal voltage has not been recovered. This improves the working ratio of the load.
TAKEHARA NOBUYOSHI
FUKAE KIMITOSHI
