Battery lower shell assembly, battery pack and vehicle

The utility model relates to the field of new energy batteries, in particular to a battery lower shell assembly, a battery pack and a vehicle. The battery lower shell assembly comprises a rivet nut, a fixing bolt, and a lower shell, a liquid cooling plate and a protection plate which are arranged in sequence; the lower shell, the liquid cooling plate and the protection plate are correspondingly provided with connecting holes, the pull rivet nuts sequentially penetrate through the connecting holes of the liquid cooling plate and the connecting holes of the lower shell, and the riveted pull rivet nuts are used for pressing and connecting the lower shell and the liquid cooling plate; and the fixing bolts penetrate into the connecting holes of the protection plate and the threaded holes of the rivet nuts from one side, far away from the liquid cooling plate, of the protection plate, so that the protection plate is connected with the liquid cooling plate and the lower shell. By arranging the rivet nuts and the fix