In January 2018 we put the first prototypes of our alphagamma® motors in the 7.5 kW class into operation on our test benches. After a total of 29,000 hours of operating experience, both in internal test operations and in external practical use, we can now proudly state that oil-free combustion engines are capable of many thousands of hours without maintenance. While we continue to focus on the chemical resistance of the burner-device when operating with sulfur- and chlorine-containing biogases, we use the time for investigations in the area of auxiliary power units (APUs) for vehicles. A prototype with approx. 20 A charging power at 24 VDC convinced us with its extremely quiet and low-vibration run of the planned development. Reason enough to make the small unit fit for long-term tests in order to meet the high demands in the area of mobility.