BATTERY DEVICE AND VEHICLE

A battery device according to an embodiment includes at least one assembled battery BT; first main switches MCP, MCM that switch an electrical connection state of main circuits C1P, C2M connected between the assembled battery BT and the load; second main switches RP, RM that switch an electrical connection state of second main circuits C2P, C2M branched from the main circuits C1P, C2M and are connected between the assembled battery BT and the load; a battery management circuit 10 that controls operations of the first main switches MCP, MCM based on an operation command supplied from the load; and a power supply circuit 20 that supplies power to the battery management circuit 10 and second main switches RP, RM when a start command supplied from the outside is ON.