A pressure maintenance device includes: a hydraulic device inside a housing of a battery module together with a plurality of battery cells, the hydraulic device being configured to change its volume to offset a pressure change inside the housing due to def...

This invention relates to a fluid accumulator comprising a wall (2) encompassing a reservoir (1) for receiving the fluid, part of the wall being elastically deformable. The wall (2) of the fluid accumulator comprises a first wall portion (2A) that is made ...