ELECTRICAL STORAGE APPARATUS FOR USE IN AUXILIARY POWER SUPPLY SUPPLYING ELECTRIC POWER FROM ELECTRIC STORAGE DEVICE UPON VOLTAGE DROP OF MAIN POWER SUPPLY

摘要

In an electrical storage apparatus including an electric storage device connected between a main power supply and a load, a first bypass FET and a bypass diode which are connected in series between the main power supply and the load are provided, and first and second main path FETs connected in series between the electric storage device and the load are provided. A controller judges that the first bypass FET suffers an open-circuit failure if the voltage (Va) of the load is equal to or smaller than the first threshold value Vth 1 or if the voltage (Vc) at the connection point between the first bypass FET and the bypass diode is equal to or smaller than the second threshold value Vth 2 , when the first bypass FET is turned on and the first main path FET and the second main path FET are turned off.