This model simulates the startup of an internal combustion engine. The model is primarily divided into three parts: battery, alternator, and engine.The battery model consists of two coupled components: A thermal component and an electrical component. The power losses in the electrical component are fed into the thermal component and cause a rise in temperature. The thermal component provides the operating temperature to the electrical component, which affects the performance of the battery.A simple alternator model is used to simulate a typical peripheral device load and to provide a charge back into the battery. The engine subsystem models the crankshaft, conrods and pistons, the cam shafts and valve train. This gives a detailed model of the inertial forces that the starter motor experiences during the startup cycle.