SAE J3400 - Battery Design

NACS — North American Charging Standard

SAE J3400 is the SAE International standardisation of the North American Charging Standard (NACS), originally developed by Tesla as its proprietary connector. Following Tesla’s decision to open the standard in 2022, SAE formalised it as J3400 in 2023. The standard defines a compact combined AC and DC charging connector that handles both AC (Level 1 and Level 2) and DC fast charging through a single connector. Major US automakers and charging networks adopted NACS following Tesla’s opening of the standard.

Published by: SAE International
Current edition: SAE J3400:2023
Previously known as: Tesla NACS connector
Related standard: SAE J1772 (CCS1 AC charging, now largely superseded by J3400 in North America)

Scope

SAE J3400 covers the physical connector, ratings, and basic signalling for the NACS connector. It applies to electric vehicles and charging equipment using the NACS interface in North America. The connector supports Level 1 (120 V AC), Level 2 (240 V AC), and DC fast charging up to 1000 V / 900 A (900 kW peak capability).

Key Specifications

Connector Design

The NACS connector is significantly smaller than the CCS1 combo connector it replaces. It uses two main power pins (for both AC and DC) and a single smaller pin for signalling and low-current communications. The locking mechanism prevents disconnection under power. The compact form factor reduces vehicle integration packaging requirements.

AC and DC Mode Operation

The same physical connector handles both AC and DC charging — the operating mode is determined by communication between vehicle and EVSE. For DC fast charging, the connector supports the CAN-based communication protocol used in the Tesla Supercharger network, with ISO 15118 compatibility being developed for broader interoperability.

Disclaimer: This is not a definitive guide, just an indication and it is important that you always go back to the source for legislation.