Battery box body, battery box and power automobile

The utility model discloses a battery box which comprises a box body and a piston mechanism, the piston mechanism comprises a pipeline and a piston, the pipeline is connected with the box body, and the piston is located in the pipeline. The piston divides the pipeline into a first cavity and a second cavity, the first cavity is communicated with the box body, the second cavity is communicated with the atmosphere, a cover is arranged at the connecting end of the second cavity and the atmosphere, and a vent hole is formed in the cover. The utility model further discloses a battery box and a power automobile. A traditional ventilation valve is replaced by the piston mechanism, so that the air pressure in the battery box is balanced, and moisture is prevented from entering the battery box through the ventilation valve to form condensation. Compared with the mode that condensation can only be slowed down by controlling air inlet and outlet in the industry, the method is greatly improved. 本实用新型公开了一种电池箱体，包括箱本体和活塞机构，