Abstract: A drive system includes a first energy storage, a second energy storage, a voltage transformer, a drive apparatus, a detector, and circuitry. The first energy storage outputs a first voltage. The second energy storage outputs a second voltage different from the first voltage. The voltage transformer transforms at least one of the first voltage and the second voltage. The drive apparatus is driven with power supplied from at least one of the first energy storage and the second energy storage. The detector detects a fault in at least one of the first energy storage and the second energy storage. The circuitry is configured to control the voltage transformer in a first control mode or in a second control mode.

Abstract: An energy storage device includes a first energy storage, a second energy storage, a voltage converter, and a controller. The first energy storage has a first resistance to degradation of a charging capacity of the first energy storage. The second energy storage has a second resistance to degradation of a charging capacity of the second energy storage higher than the first resistance. The voltage converter converts a voltage output from the second energy storage or supplied from an external electric power source to charge at least one of the first energy storage and the second energy storage. The controller controls the voltage converter so as to supply electric power from the second energy storage to the first energy storage before charging the at least one of the second energy storage and the first energy storage with electric power supplied from the external electric power source.