A memory system and storage device are provided, including: an auxiliary power device having at least one capacitor, wherein the at least one capacitor has a first path for leakage current; a charging circuit including a switch connected to the auxiliary power device; and a state determining circuit connected to the auxiliary power device, wherein the state determining circuit includes a path circuit connected in parallel with the at least one capacitor to form a second path having at least one of a resistance lower than a resistance of the first path or a current source.