ENERGY STORAGE DEVICE AND METHOD THEREOF FOR SUPPLYING POWER

An energy storage device and a method thereof are provided. The power transfer circuit transfers a DC voltage provided by a battery module into an AC output voltage to provide the AC output voltage to an output end of the power transfer circuit for providing power to a load. When the AC output voltage is at a default phase, the power transfer circuit is disabled in a default period, and whether the energy storage device may be shut down is determined according to a voltage difference of the AC output voltage sensed by a sensing circuit during the default period.