BATTERY BOX

A battery box including a lower box body, where the lower box body includes a first plate and a second plate. The first plate includes: a bottom wall; a peripheral wall connected to a periphery of the bottom wall and extending upward; and the bottom wall and the peripheral wall form an accommodating space opening upwards; the second plate is fixed to the bottom wall from a bottom and engages with the bottom wall to form a flow passage. The second plate is provided with: a second protrusion protruding to the first plate from a side facing away from the first plate and extending along a transverse direction; and an opening running through the second protrusion in a height direction and extending along the transverse direction, the second protrusion of the second plate being connected to the bottom wall of the first plate in a sealed manner.