Abstract: Disclosed is a portable battery device including a casing and a battery unit housed therein, and consisting of a plurality of battery elements. The battery device includes a surface unit for compartmentalizing the internal volume of the casing, defining sealed housings, the ends of the elements come respectively into supporting engagement, by or with the opposite end portions of the bodies of the battery elements, with the opposite compartmentalizing unit. The remaining parts of the bodies of the elements situated between the opposite compartmentalizing element are directly exposed to the outside environment through perforated or discontinuous portions of the wall of the casing.