In the last days of May 2025, SAE International expanded the J3400 family of charging standards with the new SAE J3400/2 – Connectors and Inlets for the North American Charging System (NACS) for Electric Vehicles. The latest standard defines the physical architecture of EV connectors and inlets so they can support a voltage of up to 1,000 volts.

Originally, the Tesla-developed connector was designed for up to 500 volts. Tesla announced the opening of its proprietary charging system under the NACS name in December 2022. To support voltage up to 1,000 volts, Tesla proposed a set of hardware changes (increased isolation between the positive and negative terminals on the connector), which have since been adopted as part of the SAE J3400 standard (see the difference between NACS and SAE J3400 plug here). The charging inlet is geometrically the same because it’s crucial for backward compatibility (both connector types fit all the NACS/SAE J3400 inlets).

“Developed by SAE’s Hybrid-EV Committee, the new standard defines the physical architectural and mechanical specifications of the EV connector and inlet, enabling safer and faster electric vehicle charging across North America. SAE J3400/2 standardizes the physical architecture of EV connectors and inlets using 2D mechanical drawings and 3D modeling. This gives OEM and charging equipment engineers the critical specifications needed to develop interoperable hardware.”

From left: the NACS and SAE J3400 connectors. (Source: SAE International)

With the SAE J3400/2, 1,000-volt connectors and inlets are fully standardized. This marks the official formal launch. However, many manufacturers have already deployed their 1,000-volt systems, as the technical details have already been available for interested parties for quite some time.

Below is an illustration of the SAE J3400 charging inlet and connector supporting up to 1,000 volts (the simpler, more compact version of the connector for up to 500 volts still can be used for AC and DC applications):

SAE International publishes the SAE J3400/2 Standard to accelerate safer, faster EV charging across North America. (Source: SAE International)

Dr. Rodney McGee, Ph.D., P.E., chairman, SAE J3400 NACS Task Force, and Research Engineer at the Transportation Electrification Center at the University of Delaware, said:

“The publication of SAE J3400/2 as an SAE International standard represents our confidence in the maturity of the 1000-volt-capable NACS coupler for reliable and safe bidirectional power transfer. During our open-to-the-public meetings, our group will continue to lead the development of industry-led vehicle standards expeditiously.”

Christian Thiele, Senior Director, Global Ground Vehicle Standards, SAE International, said:

“By standardizing these mechanical details, J3400/2 allows manufacturers to design and deploy EV charging infrastructure more rapidly. This is a critical step forward in supporting widespread EV adoption. The broader J3400 standard also ensures system-level consistency, covering communications, AC/DC power delivery, cybersecurity, and vehicle-to-everything (V2X) capabilities.”

The work on the SAE J3400 will continue as there are more things to come. We are especially interested in the standardization of bi-directional energy transfer.

Here is the list of the SAE J3400/NACS “Family of Standards”:

J3400™ – North American Charging System (NACS) for Electric Vehicles
General requirements for NACS, including communication protocols, AC/DC power transfer, interoperability, security, and V2X
https://www.sae.org/standards/content/j3400/

J3400/1™ – Electric Vehicle Charging Adapter Safety and OEM-Qualified Device Designation
Covers physical, electrical, and performance requirements for adapters
https://www.sae.org/standards/content/j3400/1/

J3400/2™ – Connectors and Inlets for the North American Charging System (NACS) for Electric Vehicles
Defines physical architecture through 2D drawings and 3D modeling
https://www.sae.org/standards/content/j3400/2_202505/