System for fixing a plurality of battery packs stacked one on top of the other on board a vessel, the vessel comprising a battery room whose length extends along an X axis and is delimited by a back wall, the width extends along a Y axis and is delimited by two lateral walls (16, 17) and the height extends along a Z axis and is delimited by a floor and a ceiling; each battery pack presenting a substantially parallelepipedal shape defining two lateral walls (22-1, 22-2), a proximal wall, a distal wall, an upper wall and a bottom wall, each lateral wall (22-1, 22-2) defining a plurality of fixing grooves; in a fixed position, the battery packs being designed to be disposed in several layers on the floor of the battery room between its lateral walls (16, 17) and against the back wall, the battery packs of the same layer being designed to be disposed next to each other adjacent by one of their lateral walls (22-1, 22-2) so that the fixing grooves of these lateral walls (22-1, 22-2) are disposed opposite and so that the distal walls of these packs are adjacent to the back wall; the system comprises: - a plurality of adjustable wedges, each adjustable wedge being designed to be inserted into a hole formed between two fixing grooves of two battery packs disposed in the fixed position next to each other on the other in the same layer, to block the battery packs between the lateral walls (16, 17) along the Y axis by adjusting the adjustable wedge; the system being characterized in that it further comprises: - a plurality of wall hooks, each wall hook being designed to be mounted on the back wall facing the distal wall of a battery pack in the fixed position; - a plurality of fixing hooks, each fixing hook being designed to be mounted on the distal wall of a battery pack and to block this battery pack in the position fixed along the X axis by interaction with the corresponding wall hook. each battery pack presenting a substantially parallelepipedal shape defining two lateral walls (22-1, 22-2), a proximal wall, a distal wall, an upper wall and a bottom wall, each lateral wall (22-1, 22-2) defining a plurality of fixing grooves; in a fixed position, the battery packs being designed to be disposed in several layers on the floor of the battery room between its lateral walls (16, 17) and against the back wall, the battery packs of the same layer being designed to be disposed next to each other adjacent by one of their lateral walls (22-1, 22-2) so that the fixing grooves of these lateral walls (22-1, 22-2) are disposed opposite and so that the distal walls of these packs are adjacent to the back wall; the system comprises: - a plurality of adjustable wedges, each adjustable wedge being designed to be inserted into a hole formed between two fixing grooves of two battery packs disposed in the fixed position next to each other on the other in the same layer, to block the battery packs between the lateral walls (16, 17) along the Y axis by adjusting the adjustable wedge; - a plurality of adjustable wedges, each adjustable wedge being designed to be inserted into a hole formed between two fixing grooves of two battery packs disposed in the fixed position next to each other on the other in the same layer, to block the battery packs between the lateral walls (16, 17) along the Y axis by adjusting the adjustable wedge; the system being characterized in that it further comprises: - a plurality of wall hooks, each wall hook being designed to be mounted on the back wall facing the distal wall of a battery pack in the fixed position; - a plurality of fixing hooks, each fixing hook being designed to be mounted on the distal wall of a battery pack and to block this battery pack in the position fixed along the X axis by interaction with the corresponding wall hook. - a plurality of wall hooks, each wall hook being designed to be mounted on the back wall facing the distal wall of a battery pack in the fixed position; - a plurality of fixing hooks, each fixing hook being designed to be mounted on the distal wall of a battery pack and to block this battery pack in the position fixed along the X axis by interaction with the corresponding wall hook.