Abstract: The improved battery-powered lawnmower includes a safety key that is automatically removed when the removable battery is removed, while at the same time blocking the battery recharger receptacle. The lawnmower also includes a control circuit that shuts off the lawnmower upon the occurrence of one or more of several predetermined conditions, including low battery voltage, the encountering of heavy grass for a period of 3 seconds or more, and high motor current that may occur when the cutting blade is jammed. The cutting blade is designed to move through any debris accumulated between the blade ends and the housing sidewall without sacrificing the lift for needed cutting and mulching. The invention also includes a unique height adjustment assembly for adjusting the height of the chassis, a handle attachment that allows the handle to be positively tightened to the lawnmower chassis, and a telescoping groove for the battery's quick connect/disconnect terminals.

Abstract: The device automatically determines whether a load is being applied to the engine, and outputs a change signal that is used to change one or more engine operating parameters accordingly, such as engine speed, engine timing, or fuel flow. The load is sensed without using a manifold pressure or throttle plate position sensor, thereby reducing the cost of the system. The load is sensed by determining a period of a first crankshaft revolution, determining a period of the successive second crankshaft revolution, and computing a difference value that is a function of the difference between the first and second periods. Since the difference value is proportional to engine load, the difference values may be compared with a reference value to determine whether a load is being applied to the engine. The reference value may be preset, may be manually determined by the operator, or may be learned by the system's software.