North American Charging System. The North American Charging System (NACS), standardized as SAE J3400, is an electric vehicle (EV) charging connector standard maintained by SAE International. Developed by Tesla, Inc., it has been used by all North American market Tesla vehicles since 2021 and was opened for use by other manufacturers in November 2022. It is backwards compatible with the proprietary Tesla connectors made before 2021. 

Between May 2023 and February 2024, almost all other vehicle manufacturers have announced that their electric vehicles in North America will be equipped with the NACS charge port, starting in 2025. Several electric vehicle charging network operators and equipment manufacturers have also announced plans to add NACS connectors.

Background 
After initial testing allowing non-Tesla EVs to use Tesla Supercharger stations in Europe in December 2019, Tesla began to test a proprietary dual-connector "Magic Dock" connector at select North American Supercharger locations in March 2023. Magic Dock allows for an EV to charge with either a NACS or Combined Charging System (CCS) version 1 connector, which would provide the technical capability for almost all battery electric vehicles  the chance to charge. While most of Tesla's North American V3 Supercharger locations currently provide exclusively NACS connectors — only 10 locations supported the CCS+NACS Magic Dock as of June 2023, increasing to 42 near the end of the year — it is expected that Tesla will outfit many North American Supercharger stations with both connector standards after 2023 as a temporary solution, in part to gain access to several billion dollars of infrastructure build-out subsidies available from the US Federal government for charging stations that include the CCS1 connectors during the mid-2020s.

History 
Tesla developed a proprietary charging connector for the Tesla Model S in 2012 and used it on all of their subsequent EVs: the Model X, Model 3, Model Y, and Cybertruck. As part of its business strategy, Tesla also built the Supercharger network across the United States.

As part of the Bipartisan Infrastructure Law passed in 2021, the US Government announced it would offer US$7.5 billion in federal subsidies to build out a nationwide network of fast chargers at least every 50 miles along America’s major roads. One requirement to access the funding was that the chargers must be accessible by multiple brands of electric cars.

In response, in November 2022, Tesla supplanted its previous proprietary charging connector, sometimes informally called the Tesla charging standard, with a new "North American Charging Standard" (NACS) and opened the standard to make the specifications available to other EV manufacturers. Unlike the Tesla proprietary connector which uses CAN bus to communicate, NACS uses the same ISO 15118 protocol as CCS, making any CCS vehicle electrically compatible with NACS. Only a simple pass-through adapter is needed to make CCS vehicles compatible with NACS. On the other hand, Tesla vehicles built prior to 2021 are incompatible with CCS and require an ECU retrofit to become compatible with CCS. However, the Tesla Supercharger network remains backward compatible with the prior proprietary standard.

Tesla argued that NACS should become the connector of choice because it is more compact, Tesla vehicles outnumber CCS-equipped vehicles by a margin of two-to-one, and Tesla's Supercharging network has 60% more stalls than all the CCS-equipped networks combined. At the time it was seen as a last-ditch effort to save the Tesla connector.

In May 2023, Ford Motor Company became the first large automaker to announce that it would use NACS with its electric vehicles. The company announced that starting in 2025, all new Ford electric vehicles will have native NACS charge ports and starting in 2024, prior models will be able to connect to NACS chargers by use of a NACS to CCS1 adapter. Ford's announcement began a rapid shift in the industry, with many other vehicle manufacturers making similar announcements between May and December 2023.

The adoption by almost all other EV manufacturers in North America is considered acknowledgement that Tesla's Superchargers were the most reliable and most widely-available, and that the design of the connector was superior.  It also is expected to be a stable source of recurring revenue for Tesla.

On June 27, 2023, SAE International announced that they would standardize the connector as SAE J3400. In August 2023, Tesla issued a license to Volex to build NACS connectors. The technical information report was published by SAE on December 18, 2023. The recommended practice, which changed the acronym to mean "North American Charging System", was published by SAE on September 30, 2024.

After widespread industry adoption of the NACS by a large number of automotive manufacturers throughout 2023, the US government stated public support for the NACS standard in December 2023. As a result, the Federal Highway Administration will develop detailed regulations on how the new SAE-standard NACS plug fits into the $7.5 billion charging network infrastructure buildout subsidies program.

Tesla officially opened up more than 15,000 charging stalls to Ford owners on February 29, 2024. The company said its technicians had spent the prior six months retrofitting stalls with new electronics to allow them to communicate with CCS-equipped vehicles while remaining backward compatible with the proprietary CAN bus communications. Tesla says it plans to eventually retrofit all of its charging stalls with the new electronics.

Description 
The NACS connector can support both AC charging and DC fast charging.

Technical specifications 
NACS connector exists in two different configurations, one that supports up to 500 volts and another that supports up to 1,000 volts and is backward compatible with the former.

No maximum current rating is specified by the NACS. Any amount of current is allowed so long as the temperature of the connector's interface does not exceed 105 °C. Tesla claims to have operated the connector at upwards of 900 amperes continuously.

The current version 3 Tesla Supercharger can deliver up to 250 kW of power, but this is not the maximum the NACS connector is capable of.

When AC power is used, the NACS system can deliver up to 80 amperes at 277 volts (a voltage derived from a three-phase commercial power supply at 480 volts). However, in a common configuration, NACS provides up to 48 amperes of current at 240 volts (the typical residential voltage of the North American split-phase electric power system), i.e. 11.5 kW.

Operation 
The NACS connector has a single button located on the top center of the handle. When the button is depressed, a UHF signal is emitted. When the connector is locked in place, the signal commands the vehicle to retract the latch holding the connector in place. When the connector is not locked in place, the signal commands the nearby vehicle to open the door covering the inlet.

Pin layout 
The NACS uses a five-pin layout—the two primary pins are used for both AC charging and DC fast charging:

 The DC+/L1 pin provides either the positive side of the DC voltage link or, when using AC, it provides either  in a split-phase connection or the sole Line in a single-phase connection.
 The DC−/L2 pin provides both the negative side of the DC voltage link or, when using AC, it can serve as either  in a split-phase connection or the neutral in a single-phase connection.
 The G, or Ground, pin provides a connection between the earth and the vehicle chassis. The ground pin is also used as a reference point for the CP and PP signals and to measure the isolation of the electrical systems.
 The CP, or Control Pilot, pin is used as a digital communication path between the charging system and the vehicle. The control pilot uses pulse width modulation to communicate the charging state and current in accordance with IEC 61851. Power Line Communication is superimposed onto the control pilot line while DC charging.
 The PP, or Proximity Pilot, pin carries a low-voltage signal and is used to determine the status of the vehicle connector. When the button on the plug is depressed to unlock the connector, a switch on the Proximity Pilot circuit is opened, stopping the flow of electricity.

Pin usage is the same as the SAE J1772 connector when used for AC charging.

Adoption

Automakers 
In May 2023, the Ford Motor Company became the first large automaker to announce that it would use NACS with its electric vehicles. Starting in 2025, new Ford electric vehicles will have native NACS charge ports and in 2024 prior electric Ford models will be able to connect to NACS chargers by use of a NACS to CCS1 adapter. Between June 2023 and February 2024, several other automakers and automotive groups announced that they would also equip their EVs sold in the North American market with NACS charge ports starting in 2025. Adapters will be available for older models.

The automakers that committed to this transition are:  

Mitsubishi Motors is the only legacy automaker who has not announced that it will adopt NACS.

Charging networks 
Prior to the NACS being made an open standard in late 2022, several electric vehicle charging network operators had added a few Tesla charging connector adapters to legacy CHAdeMO-standard charging stations. These included the ONroute rest stop network in Ontario, Canada, where a Tesla adaptor was permanently attached to a CHAdeMO cord, and REVEL opened a charging station in Brooklyn, New York for a while after they were denied a license to operate a Tesla ride-hailing fleet in New York City. Ivy Charge in Ontario, Canada, announced plans to include CCS1-to-Tesla adaptors for some of their stations. Also EVgo, who added optional Tesla adaptors to CHAdeMO cords. In June 2023, EVgo announced it will add NACS connector support to more of its chargers.

In June 2023 several other EV charging station providers also announced plans to add NACS connector support to their chargers. These include FLO, a Quebec-based EV charging station company with over 90,000 chargers. EV fast-charger company FreeWire Technologies also announced plans to equip its battery-integrated Boost Chargers with NACS plugs by mid-2024. BC Hydro, Blink Charging, ChargePoint, Electrify America, and EVgo have also announced plans to add NACS connectors to their charging networks. In September 2023, hotel chain Hilton Worldwide announced an agreement with Tesla to install chargers with 20,000 NACS connectors across 2,000 of its properties in North America by 2025.

Equipment manufacturers 
Several equipment manufacturers have announced that they plan to add NACS connectors to their products.  the list includes ABB, BTC Power, Tritium and Wallbox.

Competing standards 

Other charging standards for high-power DC charging of electric vehicles include:

 Combined Charging System Type 1 (CCS1): Widely used for DC fast-charging in North America and South Korea at non-Tesla charging stations. Tesla offers a CCS1 to NACS adapter for purchase. Some Superchargers offer a NACS to CCS1 adapter kept in a “magic dock” on the pylon.
 Combined Charging System Type 2 (CCS2): Legally mandated DC fast-charging standard for Europe and Oceania. Tesla vehicles sold in those countries after May 2019, and newer Tesla Superchargers use CCS2. Older Tesla vehicles can be retrofitted to use CCS2 with an adapter.
 CHAdeMO: Widely used for DC fast-charging in Japan and equipped on some vehicles in North America and Europe. Tesla vehicles sold in Japan are equipped with NACS. Tesla offers a CHAdeMO to NACS adapter for purchase.
 GB/T: Legally mandated DC fast-charging standard in China. Tesla vehicles sold in China use GB/T.

As of November 2021, Tesla's Supercharger network was the largest DC fast-charging network in the US. However, other BEV competitors in the USA were previously unable to take advantage of the Supercharger network before the release of "Magic Dock." Tesla cars, on the other hand, came bundled with a SAE J1772 adapter – which allowed Tesla owners to take advantage of the large number of slower Level 2 AC charging stations that are fitted with J1772 plugs.

A review of the images of the competing charging standards shows that the NACS connector is the most compact.

Criticism 
Tesla's decision to name its connector the "North American Charging Standard" was initially criticized by CharIN, a competing charging standards body, in late 2022 because, at the time of its announcement, it had not gone through a process to be published or recognized by a standards development organization. The process to be published or recognized is collaborative and allows all interested parties to contribute their ideas. The Charging Interface Initiative (CharIN), the association responsible for the competing Combined Charging System (CCS), criticized Tesla's process of developing NACS, but subsequently recognized that while the connector does not use the CCS standard, it does use the same standard communications protocols created for CCS.

SAE Standard J3400 
In June 2023, SAE International announced that it would begin the process to formally standardize the NACS. On July 11, 2023, SAE created a task force to handle further development of the standard and to publish it under the SAE J3400 moniker. A "Technical Information Report" − a step towards a full standard − was published by SAE on December 18, 2023. The "Recommended Practice" was published by SAE on September 30, 2024.

Gallery

References

External links 

 SAE J3400 standard
 SAE J3400 recommended practice
 Patent USD694188S1 for NACS charging connector

Automotive standards
DC power connectors
Electrical power connectors
Tesla, Inc.
Charging stations
2012 introductions