A motorized window treatment may provide a low-cost solution for controlling the amount of daylight entering a space through a window. The window treatment may include a covering material (e.g., a cellular shade fabric or a roller shade fabric), a drive assembly for raising and lowering the covering material, and a motor drive unit including a motor configured to drive the drive assembly to raise and lower the covering material. The motorized window treatment may comprise one or more battery packs configured to receive batteries for powering the motor drive unit. The batteries may be located out of view of a user of the motorized window treatment (e.g., in a headrail or in a battery compartment). The motorized window treatment may use various power-saving methods to lengthen the lifetime of the batteries, e.g., to reduce the motor speed to conserve additional battery power and extend the lifetime of the batteries.