J2908_202301 Vehicle Power and Rated System Power Test for Electrified Powertrains



Issuing Committee
This SAE Information Report provides test methods and determination options for evaluating the maximum wheel power and rated system power of vehicles with electrified vehicle powertrains. The scope of this document encompasses passenger car and light- and medium-duty (GVW <10000 pounds) hybrid-electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and fuel-cell electric vehicles (FCEVs). These testing methods can also be applied to conventional ICE vehicles, especially when measuring and comparing wheel power among a range of vehicle types.
This document version includes a definition and determination methodology for a rated system power that is comparable to traditional internal combustion engine power ratings (e.g., SAE J1349 and UN ECE R85). The general public is most accustomed to “engine power” and/or “motor power” as the rating metric for conventional and electrified vehicles, respectively. Wheel power will always be a lower-power result, owing to losses in the drivetrain that take power away from the power-producing components as it flows to the wheel. The methods in this document for determining rated system power were developed recognizing that no single approach is suitable for all powertrains without some variations specific to the powertrain type (e.g., BEV versus HEV) and the limits of test practicality.
Additional power-related tests are included to address unique operational capabilities of electrified vehicles.
Power ratings provided for ICE vehicles are obtained from component-level tests of the engine (SAE J1349). However, electrified powertrains often consist of multiple power-producing components that may include an engine and one or more electric motors configured and integrated in a variety of ways. To find an objective determination of the powertrain power among all types of electrified vehicles, SAE J2908_201709 established a wheel power test (WPT) procedure. Because wheel power results incur losses in the drivetrain not present in traditional engine power ratings, SAE J1349 and wheel power are not suited for direct comparisons. This revision adds a methodology (with several options) building upon the established SAE J2908 WPT results to make a total propulsion system power determination (termed “rated system power”). Rated system power is defined as the maximum sum of the mechanical power outputs of the individual power-producing components used in propulsion. This method facilitates comparisons to existing engine power ratings established in SAE J1349 and to electric motor power ratings in SAE J2907. It provides common nomenclature, assumptions, conditions, and procedures for expressing electrified vehicle power ratings to consumers and the engineering community.
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SAE International Information Report, Vehicle Power and Rated System Power Test for Electrified Powertrains, SAE Standard J2908_202301, Revised January 2023, Issued September 2017, https://doi.org/10.4271/J2908_202301.
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Jan 17, 2023
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Information Report