Abstract: Various embodiments are described herein for a pressure valve for a battery pack comprising a housing that has a cavity, a first plate inside the cavity and an expansible chamber inside the cavity between the first plate and the bottom of the housing. The first plate and the expansible chamber have openings that are in fluid communication with a gas inside the battery pack. The expansible chamber is deformable in order to contract or expand in response to changes in pressure in the gas within the battery pack and the first plate is movable relative to the bottom of the housing.