Mr. Schulte presented working paper HDH-09-05 on the experience with chassis dyno testing in the context of the EU CO2 work program. The presentation mainly focuses on energy recuperation in real world operation vs. chassis dyno operation for an articulated city bus.

In case of parallel activation of the mechanical and electrical (recuperation) brake system, brake forces of the axle(s) not in operation/rotation on the chassis dyno may be “over” recuperated by the axles in operation/rotation, which would give a positive effect to the final test result. This might require additional testing of the mechanical brake forces of the HDV. The recuperation correction is shown on pages 6 to 9. Other issues with chassis dyno testing are the necessity of coast-down measurements, which are often not possible, the cooling of power electronics, converter and energy storage, and additional measurement systems for electrical values in a high-voltage environment. Japan indicated that measurement of current is sufficient, since battery voltage normally does not change very much.