A battery power supply (1) for an industrial truck (8) used in a potentially explosive area is provided, having a housing (2) having a housing body (47) and a lid (4), wherein the housing body (47) has a receiving chamber (48) for receiving a battery tray (3) that has an inner chamber (20) having a traction battery (25) arranged therein, and the lid (4) is releasably placed on the housing body (47) using securing means (53), and the battery tray (3) has a battery tray lid (49) and a base (26) having walls (17, 18) extending away from the base (26), wherein, in a region adjacent to the base (26), at least one wall (17, 18) has a recess (19) penetrating the wall (17, 18) into the inner chamber (20).