Tesla's new charging standard (NACS) and the $7.5 billion in NEVI funding

Is Tesla finagling to grab federal NEVI dollars for Supercharger network?

Last week’s announcement from Tesla to create the North American Charging Standard (NACS) from its proprietary charging plug has raised serious questions in some quarters. Tesla’s plan is a smack in the face of regular standardization efforts, and it seems aimed at satisfying the requirements of the National Electric Vehicle Infrastructure (NEVI) program. By doing that Tesla could be in line for federal dollars going to the buildout of EV charging infrastructure in the USA.

Electric vehicle charging station guide

That’s a lot to unpack, so let’s take it one piece at a time.

Tesla’s backward approach to Standards

Tesla unilaterally declared that their “Supercharger” charging plug is now the North American Charging Standard (NACS). The reasoning is that the EV industry has not coalesced to use a single charging connector, and since Tesla’s charging connector is so much better then it should be adopted by the EV industry.

This is not how Standards are made, by unilaterally declaring something to be a standard. Standards are made by Standards organizations. These organizations form committees made of interested stakeholders who jointly work out all the details. I know about this first hand, having been part of multiple standards committees in my career. I am currently a member of two committees, one of which is related to electric vehicle charging. The result from a standards committee is a dry boring document full of stiff languaging that precisely documents the topic of the standard.

J1772 extension cords

For years Tesla could have brought their charging connector to the SAE J1772 committee for consideration. But, Tesla did not do so. Well, there is a timing issue to consider, in that the CCS Type 1 connector was developed before the Tesla Model S was released. Therefore, Tesla did not have a finished connector to bring to the committee before the SAE J1772 committee finished the CCS standard. On the other hand, in March 2018 the CharIN alliance (the group that develops and promotes the CCS charging protocol) held a major meeting directly across the highway from Tesla’s factory in Fremont CA. Tesla did not attend, even though the meeting was literally held on their doorstep.

Tesla did not open the Supercharger network to all comers

The documentation Tesla released contained technical drawings of the charging connector, CAD files for the connector, and the fact that the analog J1772 signals are used for AC charging on this connector. That’s it.

Tesla did not release details of the Supercharger network. This means that Tesla has not opened the Supercharger network to be used by all EV manufacturers.

Tesla is encouraging manufacturers of both EV Charging Stations and electric cars to adopt the NACS connector. But, since Tesla did not release the Supercharger protocol, these manufacturers can only implement AC charging over the connector. That means we’re extremely unlikely to see a 3rd party charging station manufacturer building DC Fast Charging stations compatible with the Supercharger network. Likewise, charging network operators are unlikely to install any DC Fast Charging stations compatible with the Supercharger network.

Electric vehicle charging station guide

Tesla says they’re going to (or are) working with “standards bodies”

Buried in half of a sentence in Tesla’s announcement is a claim that “we are actively working with relevant standards bodies to codify Tesla’s charging connector as a public standard. ” Tesla did not name the “standards bodies” in question, nor explain why it is plural (standards bodies) rather than singular (standard body).

What is this unnamed organization(s) that will help Tesla create an actual standard for the NACS connector? Does this organization have any standing with either the Society of Automotive Engineers (SAE) or IEEE? Both SAE and IEEE are deeply involved with existing standards work related to all kinds of things, including electric vehicle charging. The SAE J1772 committee heads up all things related to EV charging, for example.

If Tesla is seriously interested in properly standardizing the NACS charging connector, shouldn’t they be naming the standards body/bodies in question?

Maybe — since China does not have a single EV charging standard — Tesla is working with a Chinese standards organization on standardizing NACS. In China, Tesla’s cars are sold with two charging ports because in China there are two standards.

J1772 extension cords Tesla J1772 adapters Open the door to the Tesla Destination Charger network using these Tesla-J1772 adapters


Tesla is really interested in NEVI

In November 2021, the US Congress passed the Bipartisan Infrastructure Bill (BIL), which is also known as the Infrastructure Investment and Jobs Act (IIJA), (Pub. L. 117-58). This law included $7.5 billion for EV infrastructure and $7.5 billion to electrify public transport.

One result of this is that the Federal Highway Administration (FHWA) started a “Rulemaking” procedure, docket number FWHA-2022-00008, called the National Electric Vehicle Infrastructure Formula Program (NEVI). Rulemaking is the process by which bureaucracy sets the regulations it enforces. Another useful document, published in February 2022, The National Electric Vehicle Infrastructure (NEVI) Formula Program Guidance, is a more human-friendly description.

That was a lot of bureaucrateze, but was useful context. NEVI is a US Government program tied to a $7.5 billion program related to building EV infrastructure across the USA. It’s very likely that Tesla wants to snag some of those dollars. Further, the NEVI program is very clear on requiring standard charging protocols. Since Tesla’s charging network is based on a proprietary connector, and a proprietary charging protocol, Tesla probably recognizes it needs to make some changes.

The Rulemaking announcement for docket number FWHA-2022-00008 makes a clear call for a standards-based approach to all phases of electric vehicle charging. Some examples are:

  • Interoperability of EV charging infrastructure.
  • A seamless national network of EV charging infrastructure.
  • Interoperability requirements for charger-to-EV communication, ensuring that charging stations are capable of performing smart charge management, and “Plug and Charge”.
    • Charge management means the ability to coordinate EV charging usage with electricity grid conditions to prevent overload conditions.
    • “Plug and Charge” means the simplification of the EV charging experience, and supports an EV driver to utilize any charging station even if s/he does not have a membership with the charging network.
    • UPDATE: It was pointed out to me that the documentation released by Tesla does discuss “data communication” occurs while the NACS connector is used in DC charging mode, and that this communication is compatible with both DIN 70121 and ISO 15118. This is a big step towards Plug and Charge compatibility.
  • States are to be required to submit quarterly and yearly reports about charging network operators, identifying charging station utilization, reliability, maintenance, installation cost, and more.
  • Standard communication protocol requirements for:
    • Charging station to charging network operator.
      • OCPP is the current standard protocol. ISO 15118 is also used here for identifying the car to the charging network and supporting the Plug and Charge requirement.
    • Between charging networks.
      • OCPI is the current standard protocol.
    • Between charging networks and electric grid operators.
      • The closest relevant protocol for this is IEEE 2030.5, and possibly OpenADR.
    • Secure remote monitoring, diagnostics, control, and updates.
  • Basic charging station information (location, connector type, power level, real-time status, and real-time price to charge) must be available free of charge to third-party software developers through a standard application programming interface.
    • OCPI is the current standard protocol for this purpose.

There’s more in the NEVI document than that, but this gives a sense of where they are going. Namely, the goal is for the EV charging network to be open with seamless interoperability between multiple vendors. Further, it expects there to be accountability through reporting utilization and reliability figures to the government.

Where the charging cord meets the car, seamless interoperability means that the EV industry must coalesce on one charging connector and one charging protocol. This means that everyone turns to Tesla and Nissan to collectively say “Well?

The electric vehicle industry in North America has completely failed at developing electric vehicle charging standards. Unlike in other parts of the world, North America has multiple competing standards. Nissan, for example, sticks with CHAdeMO despite everyone saying it is on its way out. Likewise, Tesla has stuck with its proprietary charging connector, as we just described.

Source: Types of electric car charging connectors, and compatibility: A Field Guide to electric vehicle service equipment

The SAE J1772 and SAE J1772 CCS connectors are the closest to a standard charging connector for North America. These are blessed by the SAE J1772 committee, and most electric car makers have adopted these two. One exception is Nissan, where the LEAF still uses CHAdeMO for DC fast charging. The other is Tesla, who is still using the Tesla connector shown here, which Tesla has proposed as the NACS connector.

The other issue is that of charging protocol – meaning, the data exchanged between the car and the charging station related to the charging session. For AC charging, the J1772 protocol is universally used. Even though Tesla uses their proprietary connector, it uses the AC J1772 protocol. For DC fast charging, however, there are three protocols: CCS, CHAdeMO, and Tesla Supercharger.

Two connectors are shown here, IEC Type 2, and IEC Type 2 CCS, which are used in the majority of countries around the world. In such countries, these connectors are the standard used by all automakers (except for Nissan), and as a result Tesla uses the IEC Type 2 CCS connector on its Supercharger stations in those countries.

Tesla’s NACS connectors, and pin function assignments in DC charging mode. Source: North American Charging Standard TS-0023666

Tesla’s response to the NEVI proposal

Over 300 comments have been filed in response to the NEVI proposed rulemaking. Tesla provided a response in August 2022, which included these points:

  • Tesla opposes the requirement to display information like charging prices at the charging station locations. Their reasoning is that people retrieve that information via a smartphone app.
    • Note that Tesla Supercharger and Tesla Destination Charger stations do not have a user interface on the charging station, and therefore no opportunity to display any information.
    • Note that Tesla wants to avoid the cost of retrofitting a display on those charging stations.
  • The proposed rulemaking requires that each DC fast charging station have at least one CCS Type 1 connector (what’s shown as SAE J1772 CCS above). Tesla agrees with this proposal but goes on to stress the importance of allowing proprietary charging connectors, or new charging connector types, to maintain flexibility of choice at charging stations.
    • Note that Tesla is the only company using a proprietary charging connector at DC fast charging stations.
    • Note that Tesla’s response in August 2022 was well before their North American Charging Standard (NACS) announcement in November 2022.

In short, Tesla is facing a requirement that its Supercharger network must be made compatible with CCS charging. Tesla is, in August 2022, lobbying for permission to also offer proprietary charging on its Supercharger stations. By November 2022, Tesla’s tune changed to an effort for the proprietary connector to be considered to be a Standard (NACS).

Why doesn’t Tesla do as Tesla does in other regions?

In every region other than North America, Tesla has adopted the standard charging connector used in that region.

For most regions that means the IEC Type 2 CCS plug shown above. In China, there are two competing standards, and Tesla’s cars sold in China support both charging connectors. It is only in North America that Tesla has stuck with their original charging connector. In all other regions, Tesla switched from the original connector to the IEC Type 2 or Chinese connectors in use today.

Tesla is adding CCS capability to Supercharger stations

Because Tesla uses IEC Type 2 CCS connectors in most regions, the Tesla Supercharger network in those regions uses that connector. That makes it feasible for Tesla to open the Supercharger network to non-Tesla cars.

According to Electrek, Tesla is doing exactly that. The linked report discusses a pilot project in Iceland adding CCS capability to Supercharger stations and allowing non-Tesla cars to use those stations. Tesla is running similar pilot programs in multiple countries (Netherlands, etc), again relying on the IEC Type 2 CCS connector.

Because Tesla uses IEC Type 2 CCS connectors in these regions, opening the Supercharger stations to non-Tesla cars is simply a software change. That’s what comes from supporting the standard charging connector and the standard charging protocol.

Why can’t Tesla do the same in North America? Because the North America Supercharger stations use the connector now known as NACS, there isn’t a simple software change. Instead, Tesla has to make a hardware change. The changes is either to re-engineer the Supercharger stations to have both a CCS Type 1 charging cord or to sell an adapter allowing CCS Type 1 cars to use the NACS plug on Supercharger stations. Those of us with CHAdeMO cars will be left holding the short end of the stick, again.

Is Tesla misusing the standards process to certify CCS over the NACS connector?

The most charitable theory we have for Tesla’s game plan is to get one of these unnamed standards bodies to certify the NACS connector for use with the Combo Charging System (CCS) charging protocol. Then, with the NACS connector blessed by this unnamed standards body/bodies, then Tesla can go to the SAE and/or IEEE committees for incorporation of the standard. Doing it this way circumvents the normal standardization process.

CCS already runs over several charging connectors (h/t to Tony Williams on Facebook):

  • SAE-CCS-Combo1 (a.k.a. CCS Type 1 or J1772 CCS) in North America and Korea
  • CCS-Combo2 (a.k.a. IEC Type 2 CCS) in most of the world
  • CHAdeMO v3 / ChaiJa in Japan and China
  • Megawatt Charging, in Europe and other places where electric Semi’s are being deployed
  • Tesla NACS in North America only — if/when/ever it is standardized

This possible plan is discussed in my previous article on the Tesla NACS announcement. I have long felt that Tesla’s best move would be opening the Supercharger network to all comers. That would make Tesla the biggest player in electric vehicle charging in North America.

Certifying their NACS connector (as it’s now known) for use with CCS would open the door to the same plan Tesla is following in other countries. They could start with pilot projects offering CCS charging to non-Tesla cars, and they could easily create an adapter between NACS and CCS Type 1. If the North America Supercharger network gains CCS support, then the adapter could be very simple.

Here’s where we get back to Tesla begging for the regulations to allow proprietary charging plugs alongside the standards-based charging plug. Tesla probably wants to avoid this expense:

  • Retrofitting existing Tesla cars with CCS Type 1 plugs
  • Retrofitting CCS Type 1 plugs at North America Supercharger stations
  • Perhaps retrofitting displays and user interaction at Supercharger stations
  • Convincing Tesla’s customers in North America to use CCS Type 1 plugs after Tesla has convinced them of the superiority of the NACS connector

The theory is, to avoid that expense, Tesla’s gambit is to position the NACS plug as a standard. We don’t know which standard body/bodies Tesla is (or will be) working with for this. Tesla’s next step would be bringing that standard to the relevant SAE or IEEE committees, asking them to adopt the foreign standard.

AMP verifies the above plan, and adds background information

UPDATE: After publishing this post, I came across a blog post by engineers at AMP, a company specializing in energy management related to EV charging. This blog post demonstrates that the NACS documentation shows a path toward implementing CCS over the NACS connector.

Buried in the NACS technical specifications are details demonstrating that Tesla intends to use CCS over the NACS connectors. The document shows how to switch the charging connection into DC charging mode, and says that when in DC mode “communication” happens over the control pin.

Elsewhere, the technical specifications explain that the communications are compatible with DIN 70121 and ISO 15118. Both of those utilize “Power Line Communications” (PLC), which allows TCP/IP communication through the charging port at up to 10 Mbit/second. DIN 70121 is essentially an early version of ISO 15118 that lacks security features such as encryption using TLS, and encrypted digital identification of the car. The important factor here is that this communication using PLC is compatible with CCS.

AMP’s blog post goes on to theorize that NACS will allow a passive adapter to be used between a non-Tesla car and a Tesla Supercharger station.

If all this information holds up, Tesla will be able to claim its NACS connector is an actual standard (rather than a self-proclaimed pseudo-standard), and that a simple adapter allows use with a normal CCS charging port. This may be enough to satisfy NEVI rulemaking requirements.


Tesla’s NACS announcement has been controversial so far, with some praising Tesla and others raising a red flag of alarm.

My career in software engineering has me attuned to standards creating a good playing field for all stakeholders. In gasoline cars, the fuel nozzle is a standard thing as is the fuel mixture. This allows any gasoline station to deliver standard gasoline through a standard nozzle into any gasoline-powered car. There isn’t a Ford fuel mixture and nozzle, just as there isn’t a GM fuel mixture and nozzle. It enabled a wide mix of all kinds of shops selling gasoline and other services.

Another example is the Web. Over 20 years ago, Microsoft tried to use its position as the provider of the dominant web browser (Internet Explorer) to dominate the web with proprietary extensions to web standards. Fortunately the web standards community got together, and the Mozilla Foundation made sure that Firefox was a worthy competitor. Today, web standards are the way to go, with multiple compatible web browsers giving us excellent web experiences.

The NEVI rulemaking proposal has that sort of vision for electric vehicle charging. It describes an interoperable network of charging stations and vehicles from multiple manufacturers. The use of open standard protocols will allow any company to participate in this picture.

So far Tesla has been standing against that sort of result because its proprietary charging network is not open to others. It would be fantastic if Tesla’s plan for NACS is to honestly move towards open standards and interoperability with others. So far Tesla’s goal seems to be domination over the electric vehicle industry, just as Microsoft 20+ years ago sought to dominate the Internet. Today, Microsoft has engaged fully in open source and open standards communities. Hopefully, Tesla will make a similar shift and embrace open charging standards.

About David Herron

David Herron is a writer and software engineer living in Silicon Valley. He primarily writes about electric vehicles, clean energy systems, climate change, peak oil and related issues. When not writing he indulges in software projects and is sometimes employed as a software engineer. David has written for sites like PlugInCars and TorqueNews, and worked for companies like Sun Microsystems and Yahoo.

About David Herron

David Herron is a writer and software engineer living in Silicon Valley. He primarily writes about electric vehicles, clean energy systems, climate change, peak oil and related issues. When not writing he indulges in software projects and is sometimes employed as a software engineer. David has written for sites like PlugInCars and TorqueNews, and worked for companies like Sun Microsystems and Yahoo.

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