A commercial vehicle’s electrical startability

Abstract: In commercial vehicles, where the driver overnights with the engine turned off whilestill consuming electricity, it is important to know how much the battery can bedischarged before reliable engine starting is at risk. The vehicle’s ability to crank theengine, i.e. startability, changes with the vehicle’s ambient temperature and thebatteries state of charge. The aim of this project is therefore to test the startability ofa commercial vehicle and its cranking system’s behaviour at different ambienttemperatures and battery state of charge. Physical startability tests were planned andperformed on a commercial vehicle at different temperatures inside a climatechamber. The results of these tests show the torque of the vehicle’s powertrainincreasing with lowering temperature while the cranking system’s performancedecreases. This decrease in the cranking system’s performance is a result of thebattery’s lowering ability to supply power at lower temperatures.