Managing the Evolution of the EV Charging Standard

How and why SAE International’s standards experts are fast-tracking the adoption of the NACS charging connector for North America as they consider the future of EV-related standards.

Startup EV developer Rivian announced in June 2023 that it intended to adopt the NACS charging standard. (Image: Rivian)

SAE International announced in late June 2023 that it intended to standardize the Tesla-developed North American Charging Standard (NACS) EV charging connector for North America. SAE then created the J3400 NACS Task Force to expedite creation of the J3400 NACS Electric Vehicle Coupler standard.

Grayson Brulte, host of SAE’s Tomorrow Today podcast, subsequently interviewed Christian Thiele, Director, Global Ground Vehicle Standards, SAE International, and Dr. Rodney McGee, Ph.D., P.E. Chairman, SAE J3400 NACS Task Force and Chief Engineer at the University of Delaware, regarding the work of the J3400 Task Force and other aspects of standardization as electrification technology proliferates throughout the light- and heavy-duty vehicle sectors. This Q&A is an abbreviated portion of that interview.

Grayson Brulte: You’re going to standardize NACS. What does that process look like? How will you take what Tesla built with the NACS and standardize it for across the industry for use?
Dr. Rodney McGee, Ph.D., P.E. Chairman, SAE J3400 NACS Task Force and Chief Engineer at the University of Delaware. (Image: University of Delaware)

Dr. Rodney McGee: Typically, a lot of standards start off at the very conceptual stage where experts basically say, how do we want this to work? And so you literally start with a blank piece of paper and then you get some proposals and then, in, you basically, coalesce on a single sort of solution. That process typically takes some time because, you’re creating something where there was nothing before – or there were things before, but they were different, had different requirements.

The NACS standardization process is a bit different: Today that connector represents both a majority of use in full EV and also a [large] market share in charging stations, especially DC [fast]-charging stations. So, what we’re going be doing in the standards is really capturing the existing mechanical connector to make sure that when other manufacturers want to be interoperable with it, they have a standard to follow that will ensure that things work well.

Brulte: The J3400 Standard covers only the connector, not other aspects of the charging process?
Christian Thiele, Director, Global Ground Vehicle Standards, SAE International. (Image: SAE)

Christian Thiele: The J3400 is just focused on the charger unit - the fixture itself. We have other standards that are working for the interoperability point of view, the communication point of view. The standards back in the day were always focused just on the vehicle; the vehicle was a standalone entity. Now there are communication protocols that are happening with the vehicle, with the people, with infrastructure, with other places.

Brulte: Are there other challenges that you’re going to have to overcome to standardize the NACS connector?

McGee: [Adopting the] NACS does mean people have to make changes, even if it’s just at the mechanical level. There are electrical differences between NACS and J1772 that will require manufacturers to make changes.

And if, it was a different situation and Tesla hadn’t already had a lot of [charging equipment] in the field, I think there would be a lot of pressure – maybe it would be more open-ended. What exactly would be the standard? But in this case, most of the people who have joined up with Tesla and their charging system very much want to take advantage of the existing infrastructure.

When you want to take advantage of the existing infrastructure, it ‘bounds’ the work. One of my challenges is to remind people of that – this is a deployed system. Looking forward, certainly, there are going be things that’ll be added to it within the standards-development process, but just reminding people that nobody wants to adopt or build a NACS standard that’s incompatible with the existing deployment of NACS charging stations.

Comparison of Tesla’s North American Charging Standard (NACS) EV charging connector (in black) and SAE J1772 Combined Charging System (CCS) in grey. (Image: Tesla)

That’s part of the big reason to move [to the NACS standard]. A lot of people involved with standards are very much used to starting with that blank piece of paper; it helps mitigate those challenges of people wanting to reinvent the wheel, so to speak.

Brulte: The standard for the NACS connector is going to go faster than your “traditional” standards process. How is that going to be achieved?

Working with Portland General Electric, Daimler Trucks North America (DTNA) in 2021 opened the ‘Electric Island’ site with eight charging stations suitable for electric cars, buses, box vans, and semi-trucks. Such stations could accommodate the CharIN Megawatt Charging System (MCS) standard, which complies with the SAE J1772-based combined charging system (CCS), and is focused on Class 6-8 commercial vehicles with large battery and packs and the ability to accept a >1 MW charge rate. (Image: DTNA)

McGee: I think Tesla realized they needed to have a standard that was published by an organization – we use the term SDO, Standards Development Organization. They looked at the options in front of them. The two [SDOs] that would cover this kind of area are the IEC (International Electrotechnical Commission) and SAE.

Some of the international standards can take quite some time. This is due to the way that they’re essentially through national committees. In SAE, the standards are developed by individual experts from a variety both internationally from different suppliers, different automakers, general interests, and there’s a much shorter process to take into account revisions.

Overhead charging of commercial vehicles is one option to address those vehicles’ higher-power charging needs and SAE has standards development for this charging modality. (Image: U.S. DOT/Adobe Stock)

The second thing is the fact that NACS is unique in that it already exists in large numbers in the real world. And we’re not starting from a blank piece of paper. The SAE process can, when there is consensus on what we’re doing – and in this case, there is, because it’s already out there, especially when we talk about the mechanical coupler – move much quicker than would be typical.

Brulte: What is that timeline for the standard? Has SAE or the committee made a public statement around a timeline?

Thiele: We’re looking at publishing something inside of about six months and it’ll be a technical information report. Ideally a standard usually is developed anywhere from 16 to 18 months as typical timeframe. We have been as quick as 10 to 11 months and this will fall around the 11-month window.

Brulte: What happens, Christian, to the J1772 standard? Does that continue to live on? Does it live in other markets or where does that go?

Thiele: Oh yeah. It will continue to live on. There are many vehicles that are out there – obviously [using] the J1772 standard. So that will continue to live on and evolve depending on who adopts the next standard. Europe, we don’t know yet if they’re going to adopt [NACS] in Asia, we don’t know what’s going to happen in emerging markets south America. Africa, we won’t even go there yet because we’re still focused on certain levels of ICE and things of that nature; [vehicle electrification] is going to go into the future just based on infrastructure alone.

But ultimately the focus here should be to see what we can continue to do and develop. We continue to focus on the J1772 to deliver the best standard for that particular application. And even in the J3400 [NACS standard], I think we will be referencing the J1772 document because of some of the intricacies that are there from a communication protocol, etc. and technical statements that are in there just so we don’t repeat ourselves.

McGee: It’s important to remember that J1772 is also used in Japan and South Korea. There’s no indication at the moment that’s changing. There are a number of other smaller countries that may continue to use that plug and even if over time the plug becomes more common, it’s a lot of the descriptions of things that live in J1772 that may continue to be described within that document.

Brulte: What is the impact of NACS on commercial vehicles, say Class 6 through Class 8?

McGee: SAE has Ground Vehicle standards and under that are the Truck and Bus Council and the Motor Vehicle Council. The NACS Task force lives under Motor Vehicle Council. I also have standards that I work on in Truck and Bus. One of the things that come out of this discussion is a good analogy: if you’ve ever gone to one of those stations that service tractor-trailer [Class 8] trucks, you know that they have bigger filling nozzles because those vehicles need quicker energy delivery, via diesel in those cases.

They [commercial-vehicle interests] want higher-power DC charging, that’s megawatt. SAE has a megawatt-level DC charging standard, focused on those vehicles for plugin charging. A couple of years ago, SAE published overhead-charging non-handheld couplers, and the J3105 series, which is basically about electrifying city buses and vehicles like this. For DC charging, [generally] we want higher power levels than the passenger-car market, because we have batteries that are three and four times bigger.

Those vehicles may have goods, sometimes millions of dollars’ worth of goods on them. They can’t fail. They need to get to their destination. That is one of the legitimate reasons that those vehicles generally lag behind passenger-car [change and innovation], because the truck sector wants [equipment] that’s known reliable and that’s well-understood.

Even though there’s been some high-profile deployments of vehicles like electric school buses, they’re really leveraging passenger-car standards. A city bus, we pretty much drive these buses 23 hours a day, so we need overhead charging at above a megawatt. It’s really about the truck and bus [interests] deciding to electrify and then figuring out how they get there from here and making standards that sort of enable the mass deployment.

To listen to the full episode of the podcast, visit here .