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SAE’s NACS certification is ready, and it’ll fix every EV charging problem at once

Jameson Dow

Dec 15, 2023

SAE has followed through on its plan to finish its NACS certification by the end of the year, and the NACS standard is now ready to go. And the new standard promises to solve a lot of charging problems in one fell swoop.

Tesla released specifications of its charging connector in November 2022. It called it the “North American Charging Standard,” which was somewhat of an absurd name at the time, given that Tesla was the only company using it.

However, since Tesla is a majority of the US EV market, Tesla’s argument was that most of the cars and most of the DC charging stations in America already used Tesla’s connector, so it should be considered a de facto standard anyway.

For a few months, not many people took this seriously. However, Ford shook up the industry by announcing it would adopt the NACS plug on upcoming vehicles. Soon after, GM made the same move, and now basically everyone else has.

This led SAE, the professional engineering organization that develops industry standards, to take up the flag of creating a real, independent standard that is no longer in the hands of Tesla. This is an important move because many governments and companies would understandably have an issue with a single company having control over a standard that, at this point, it seems like everyone is planning to use.

How NACS will solve several EV charging problems at once

We had another chat with Rodney McGee, Ph.D., of the University of Delaware, who chaired SAE’s NACS task force. He told us that the new standard will be announced on Tuesday. He was understandably excited about the standard getting finished so quickly and explained how NACS is going to solve a lot of problems with EV charging all at the same time.

In particular, it should make charging installation cheaper for commercial entities, leading to cheaper and easier charging for businesses (including, potentially, for large apartment buildings); make charging more interoperable between commercial and personal vehicles; and unlock new possibilities for street charging for electric vehicles.

The main reason for this is the standard is preserving NACS’ support for 277 volts, as opposed to the 208-240 voltage of J1772. This simple change unlocks a cascade of benefits that should smooth out several charging problems.

Why does this matter? 277 V is one phase of a three-phase 480 V supply, which is the form that most commercial utility connections use (particularly those that support DC chargers). This means that secondary step-down transformers are no longer necessary for AC chargers, making EV charging installations cheaper and more efficient.

Making EV charging installations cheaper and easier for businesses allows for more chargers at workplaces, offering another option for people who can’t charge at home. It means more opportunity charging at any other place you might happen to park, and more opportunity charging means more EVs plugged in at any given time, which means more battery capacity available on the grid in a potential vehicle-to-grid (V2G) future.

Saving businesses money is all well and good. However, the most important point here is that making commercial installations cheaper means that mixed-use apartment buildings can more easily install banks of EV chargers without needing big transformer rooms to further step down voltages. And that means that more people will be opened up to the convenience of having a charger at the place where their car spends the most time.

The news is even good for people who don’t have a parking spot – city-dwellers who use street parking. The NACS standard includes a provision that would enable the installation of chargers in lampposts, something that we’ve seen trials of in London. There have been similar efforts in the US, but those are subpar because the J1772 standard requires a permanently attached cable, which means that streetside cables get dropped, broken, laid around, and otherwise abused.

The new NACS standard instead uses a standardized receptacle – which is, in fact, the same one used in the EU and China – which can be plugged into with a ~$100-200 carry-along cable that EV drivers can keep in their car (and the receptacle does have a locking mechanism). Making each driver responsible for their own cable makes maintenance easier in public spaces where otherwise, nobody’s really willing to take ownership of ensuring cables don’t get abused.

NACS also allows AC and DC through the same connector, unlike J1772. CCS is similar to the J1772 plug but with an additional two pins on the bottom, so the connectors aren’t identical. With NACS, the connectors are identical for both types of charging.

Another potential upside here involves medium- and heavy-duty vehicles, which could charge at up to 52 kW AC from the same receptacle as a light-duty vehicle can charge at 20 kW, using three-phase or single-phase power, respectively. 20 kW can be a bit on the low side for some larger vehicles – school buses and the like – so allowing those vehicles to charge at up to 52 kW from the same place a light-duty vehicle can charge at 20 kW would be a big boon as well.

And finally, all of these boons add together to a world where it’s easier to install and maintain chargers and easier for everyone to use those chargers wherever they’re parked, which means more cars plugged in at any given time. And if everyone is plugged in all the time, that means more capacity available for a potential vehicle-to-grid future. If V2G ever takes off, we will want to have as many cars plugged in as possible because more cars plugged in means more capacity available for the grid. And that means making AC infrastructure cheap, which is what 277 V support and carry-along cables enable.

There is one potential problem on the horizon, though: California and the US federal government (through NEVI) have both put a lot of money into charging station deployment, and the original intent of that money was to install roadside DC chargers that are as compatible as possible. So now, will those rules fully embrace NACS and allow the money to be used to install the new standard, or will they require CCS-compatible deployments so as not to leave an installed base of vehicles behind, even though CCS is now, effectively, a dead standard? (One compromise option being discussed is to require CCS for DC chargers but throw full weight behind NACS for AC chargers.)

This decision point is also a little ironic, considering NACS’ existence seems to have been spurred on by NEVI in the first place. When the government offered billions of dollars to companies that installed chargers with the requirement that those chargers be useable with multiple vehicles, that’s what got Tesla to finally offer a “standard.” At the time, it wasn’t really a standard because only Tesla was using it, and it was somewhat of a last-ditch effort to save the Tesla connector. Then, when Ford decided to use NACS, that’s what started all the other dominos falling. Now, NACS is dominant, but it only happened because of NEVI in the first place – and NEVI now has the difficult decision over whether to embrace the (positive) situation it caused, even if it will give some of the installed base an effective “use-by” date as a shift to NACS will inevitably mean fewer CCS/J1772 chargers over time.

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