The present invention is a motorized shopping cart retriever that includes a controller that attenuates the power provided to the drive system of the retriever to prevent the retriever from being utilized to move an excessively heavy load of shopping carts. By preventing the retriever and carts from being subjected to overloaded conditions, the operational lives of the retriever and carts are maximized. The retriever is also provided with a burst mode that allows the power provided to the drive system to rapidly increase past the normal attenuated level for a brief period of time in order to reduce the time required to accelerate a retriever loaded with carts to a terminal velocity.