The invention relates to a device (10) for fixing a battery (11), consisting of a support tray (12) comprising an essentially-flat support face (16) and two longitudinal flanges (17a, 17b). According to the invention, the first longitudinal flange (17a) comprises fixed lugs (20) which serve as positioning stops for a first lug (14a) of the battery (11). The support tray (12) comprises mobile lugs (21) which are connected to the second longitudinal flange (17b) and which each define a first blocking surface (22) for a second lug (14b) of the battery (11). The fixing device (10) comprises elastically-deformable actuation levers (25) which are associated with the mobile lugs (21) and a locking ramp (26) which co-operates with each mobile lug (21) and each corresponding actuation lever (25) such as to lock the battery (11) in position in the support tray (12).