Feasibility study of an idling-stop device on agricultural tractors

Idling is a vehicle condition in which the engine is running at the minimum rotational speed without accomplishing any useful work besides the generation of energy required to keep it rotating. Agricultural tractors may idle from 10 to 43% of their service time and this inoperative time must be minimized since it is deleterious for the environment, public health, and fuel economy. Idling could be reduced by adopting anti-idling devices such as the idling-stop. Despite it is well adopted on cars, it is not present on any commercial tractor. Since the engine restart requires an energy surplus from the battery to run the starter motor, idling-stop devices are not efficient for very short idling stops. This study aims to quantify the potential advantage of using an idling stop device. Engine startup tests were carried out to evaluate the electrical energy and the fuel used for the engine startup. The electrical energy was measured through an electrical current and voltage sensors placed on the battery poles. Results confirm that with very short idling periods an idling-stop device is not energy efficient since the power provided by the battery to run the starter motor is higher than the energy saved during the engine shutdown. The minimum idling time that permits energy savings is about 4 seconds.