SAE J2982_202210

This SAE Recommended Practice incorporates dynamometer test procedures that produce riding range estimates for electric motorcycles during stop-and-go urban riding on surface streets and commuting trips in urban areas that include operation on freeways. This is typically done using a “coastdown” approach by disengaging the engine and assuming all losses are aerodynamic. However, with inherent losses in an electric motor, and no way to fully disengage the motor, another approach is to use a “on-road, constant speed” (Appendix B) method for fully electric vehicles to develop dynamometer coefficients. The previous version of this document states that the engine must be disengaged in order to obtain the losses from the system in motion. In an electric vehicle, there is no way to disengage the motor. The range and losses that are obtained are false due to the fact that motor (magnetic losses) are inherent to the function of the motor, even with regeneration (backdriving the motor to energize the battery) disengaged there are continuous losses in the system. The proposed changes would be to use a “continuous motion” at a constant speed to determine the inherent losses of the system. This proposed method may be used in all electrically driven vehicles.