A window shade assembly including a shade tube configured to support a shade and extending longitudinally, a mounting bracket, a motor assembly extending within the shade tube and coupled to the shade tube, and a battery pack extending within the shade tube. A central axis extends longitudinally through the center of the shade tube. The motor assembly is configured to rotate the shade tube relative to the mounting bracket about the central axis to at least one of raise and lower the shade. The battery pack includes a battery housing and at least one battery. The battery housing couples the motor assembly with the mounting bracket and defines at least one battery bay. The at least one battery is carried within the at least one battery bay. The at least one battery is configured to store and provide energy to the motor assembly for rotating the shade tube.