A mounting bracket is provided for a vehicle battery system with a battery tray sized to receive a traction battery. The bracket has first and second sides extending between first and second ends. The bracket defines first and second apertures adjacent to the first end and positioned to cooperate with the first and second bosses to connect the bracket to the battery tray. The bracket defines a third aperture adjacent to the second end and positioned to cooperate with a mounting point on a vehicle frame. The bracket defines a transverse slot intersecting the first side and extending towards the second side, with the transverse slot positioned between the first and third apertures. A vehicle and a vehicle battery system with the mounting bracket are also provided.