SAE J3105 - Battery Design

Electric Vehicle Power Transfer System Using Conductive Automated Charging

SAE J3105 defines requirements for automated conductive charging systems for electric vehicles — systems that make the charging connection automatically without manual plug-in. These systems are designed for fleet EV applications (buses, trucks, taxis) where high utilisation rates and frequent charging make automated connection advantageous.

Published by: SAE International
Current edition: SAE J3105-1:2020 (Part 1: General requirements), SAE J3105-2 (OppCharge-style top contact), SAE J3105-3 (floor-mounted contact)
Related standard: SAE J1772 (manual AC charging), IEC 61851 (EV charging systems)

Scope

SAE J3105 applies to automated conductive charging systems for on-road electric vehicles including buses, commercial vehicles, and passenger cars equipped with automated connection systems. It covers mechanical interface requirements, electrical ratings (up to 600 V DC, high current), communication protocols, and safety interlocks for automated connection.

Key Requirements

Automated Connection Interface

The standard defines contact geometries, alignment tolerances, and mating force limits for automated connection systems. Conductive contacts must withstand the mechanical wear of repeated automated mating cycles over the vehicle service life. Ingress protection requirements ensure reliable operation in outdoor environments.

Safety Interlocks and Communication

Power must not be applied to contacts until full mechanical engagement is verified. Communication between vehicle and EVSE must confirm vehicle presence, alignment, and battery readiness before charging initiates. Immediate power cut-off on loss of contact is required.

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