An engine starter system with a duty cycle controlled switching device

An engine starter system (1) includes a power switching device (4) for controlling an armature current, a bypass relay (5) to bridge electrically the power switching device (4) or short-circuit, and an electronic control circuit (6). In the normal start mode, the electronic control circuit (6) gradually increases the armature current by varying a duty cycle of the power switching device (4). When the armature current is greater than a permissible current value of the power switching device (4), the armature (11) via the lock-up relay (5) is energized. In a startup mode according to economic operation of the armature current on the power switching device (4) is controlled until the engine has fully started.