Auxiliary power unit tops 40 Ampere

Sep 15, 2021

On August 17, 2021, the research team from frauscher thermal motors celebrated a successful milestone: the prototype of an auxiliary power unit achieved a stable charging current of 40 amps on a truck battery set with a nominal voltage of 24 volts. This means a doubling since the first runs on the test stand.

With this value it must be taken into account that the losses of the generator and the rectification are at around 20%, so that the shaft power of 1.25 kW leads to a respectable mechanical efficiency of over 30%.

The team can be proud of this, especially since it is becoming increasingly difficult to reach the efficiency levels of larger units with such small engines.

Almost as quiet as a refrigerator

Numerous optimization steps led to a remarkable improvement of the thermodynamic process. However, mechanical parts such as piston rings, bearings and guides could also be significantly improved in terms of minimizing friction work.

Stirling_engine MobilGen™-G70 by Frauscher Motors

The protype of the new engine, which will be used as auxiliary power unit. (Picture: Erwin Berghammer)

From the beginning, special attention was paid to cost-effective manufacturing processes. Almost all parts can be manufactured using CNC technology, the manual work is minimized to the minimum.

One can be fascinated by the quiet operation of the unit. The low noise emissions already lead to the conclusion that, with optimal installation conditions, the operating noise is barely as high as that of a refrigerator.

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Header picture: Erwin Berghammer