The Society of Automotive Engineers (SAE) has introduced a new standard, assigned the identifying number J2908, to measure the power of electric vehicle powertrains. It includes methods of testing, processing information from the tests, and reporting vehicle power.
SAE also calls the new testing standard the “Vehicle Power and Rated System Power Test for Electrified Powertrains.” It can be used with a variety of electrified or partially electrified vehicles, including the following.
- Battery-electric vehicles (BEVs or EVs)
- Plug-in hybrid-electric vehicles (PHEVs)
- Hybrid-electric vehicles (HEVs)
- Fuel-cell electric vehicles (FCEVs)
SAE International designed the J2908 standard to be flexible so it can provide consistent, comparable results from different testing techniques. Users of J2908 can plug in data from bench testing or direct vehicle testing and derive a power rating that can be compared directly to all other ratings using the same standard.
The SAE’s goal is a procedure for calculating a rating that is “very technology- and approach-agnostic” according to Argonne National Laboratory research engineer Michael Duoba, who sponsored the J2908 standard. This should enable independent testing labs and various manufacturers to provide standardized ratings despite the different approaches and tools they use in measuring power.
Hybrid vehicles and those with blended drivetrains are especially challenging to rate accurately for power. The new standard should make this process easier and more consistent, too.
The J2908 standard also addresses electric and hybrid vehicles with a temporary boost function. The boost can only be considered part of the overall power rating if it lasts for a minimum of 10 seconds and is readily available to the driver.
The new standard also accounts for the effects of battery charge level and environmental conditions. It also switches from an engine power test, used for previous standards, to a wheel power test.
This measures the power actually being delivered to the axles, making the test more accurate for complex electric and hybrid powertrains. The standard is flexible enough to enable testers to choose wheel dynamometer or chassis dynamometer readings to measure wheel power, depending on their preference.
One of the method’s limitations is that it requires physical testing for a truly accurate result, rather than relying on simulations.
Volkswagen is the first automaker to start using the new SAE J2908 standard for its electric vehicles. The company published a J2908 power rating on its website for the 2023 Volkswagen ID.4 EV.
As a reminder, GM plans to offer EVs in one-third of all vehicle segments by 2025 with 30 individual EV models available worldwide. These 30 new EVs are slated to include Cadillac, GMC, Chevrolet, and Buick models.
The General says the lineup will feature EVs “at all price points,” and with designs catering to a range of potential uses, such as work, adventure, performance and family. More than 40 percent of GM’s U.S. portfolio will be battery-powered by the end of 2025.