In most motor vehicles, small electric motors known as starters are used for this purpose. Since high friction and compression resistances have to be overcome during the starting process, the DC series-wound motor is particularly suitable as a starter motor due to its high initial torque.
The starter converts electrical energy into kinetic energy. Diesel vehicles or vehicles with a start-stop system have a more powerful starter. To ensure that the required torque can be achieved during the starting process, a countershaft gearbox provides the necessary reduction. The starter pinion is usually "engaged" with the aid of a magnetic switch. With gasoline engines, the starting process loads the battery with around 100 A, with diesel engines with up to 400 A. The latter is due to the higher compression ratio required. The latter is due to the higher compression required for the compression-ignition engine. In addition to the engine type (gasoline, diesel), the minimum output of a starter also depends on the engine displacement, the minimum starting speed of the unit and the required engine oil formulation (oil viscosity). For modern, turbocharged downsized engines with less displacement, a smaller starter with less power is sufficient.
