SAE J2578_200901

This SAE Recommended Practice identifies and defines the preferred technical guidelines relating to the safe integration of fuel cell system, the hydrogen fuel storage and handling systems as defined and specified in SAE J2579, and electrical systems into the overall Fuel Cell Vehicle. This document relates to the overall design, construction, operation and maintenance of fuel cell vehicles. The purpose of this document is to identify the unique requirements and criteria for the integration of fuel cell systems into vehicles. Since the publishing of the original document in 2002, the document has been used as a basis for the design of development vehicles and as a resource for national and international harmonization of codes and standards. This document has been revised to provide the latest information on fuel cell vehicle requirements based on these efforts. Other than minor typographical corrections, the following sections have been updated relative to the previous 2002–12 version: a The Foreword and Purpose were adjusted to clarify the focus of the document with regard to providing safety criteria and methodologies. b The Foreword and Sections 4.2.1, 4.2.5, 4.2.6, 4.3.1, and 4.6 were modified to reflect the publication of SAE J2579 for vehicular hydrogen systems. c Sections 3.3, 3.4, 3.29 were modified to harmonize with electrical terminology and requirements in ISO standards. d Section 3.11 was added to define and describe flammability. Sections 4.2.3, 4.2.4, and 5.2 and Appendix C were re-written to clarify fuel discharge requirements related to flammability, and a new appendix (Appendix D) was added to provide performance-based evaluations of local flammability of fuel discharges from the vehicle. NOTE: Definitions after Section 3.11 were re-numbered to reflect the insertion of new definitions. e Reactive materials were added to Hazardous Fluids in Section 3.15 to reflect materials associated with metal hydrides and fuel processors as identified in SAE J2579. f Requirements for toxicity were expanded to allow other equivalent methods to OSHA TWA for global acceptance. g In order to harmonize with ISO, the term intermediate voltage was deleted from terminology and requirements in Sections 3.16. h Section 4.1.1.1 was generalized to allow various tools to be used for risk assessment (in addition to, or instead of, FMEA). i The definition for Internal Transfer or Cross Leakage was added to Section 3.21 and associated requirements were addressed in Section 4.3.2 and Appendix D. j Section 4.1.3 and Appendix A on Fuel Cell Vehicle Crashworthiness were updated to reflect the recent publishing of SAE 1766, correct a typographical error and update fuel containment requirements, and to provide flexibility with regard to evaluating crash tests. k Prescriptive margins were eliminated from Section 4.2.3.2 with regard to Potentially Flammable Atmospheres and Section 4.2.3.3 on Potential Ignition Sources, and sections were modified to clarify requirements, particularly with regard to the management of discharges that could self-ignite. See 2007 World Congress SAE Paper 2007-01-0437 for basis of changes. l Requirements for discharges from pressure relief devices in Section 4.2.5 were updated to reflect latest understanding and a new appendix, Appendix E, was added to provide guidance. m Sections 4.2.7 and 7.2 were modified to better define defueling requirements. n Prescriptive margins for isolation test voltage were removed from Sections 4.3.3 and 4.4.3 and Appendix B. Requirements have been harmonized relative to ISO in order to provide a more wholistic approach to electric shock protection. o High voltage withstand test requirements in Sections 4.3.4 and 4.4.4 and Appendix B were harmonized relative to ISO and focused on connectors, harnesses, and bus bars. p Color requirements for labels were added to 4.4.6 and 4.7 as the document is published in black and white. The flexibility for the vehicle manufacturer to use specialized badging or other unique features to identify a fuel cell vehicle was added as a “blue diamond” or equivalent markings are not required internationally for emergency response. q Vehicle bonding requirements in 4.4.8.1 were clarified. r Capacitors were added as examples of energy storage components in Section 4.4.8.3. s Section 4.4.8.4 was updated to account for the overall resistance between earth ground and the conductive chassis, and to harmonize the requirement with standard gasoline-fueled vehicles. The original requirement of 25 megohms addressed only the wheels whereas the new requirement of 125 megohms addresses the vehicle requirement. t Electric System fault monitoring requirements were clarified in Section 4.4.9. u Requirements for the Use of Electric Supply Equipment in Section 4.4.10.1 were clarified, backfeed protection for stacks was made optional based on need in Section 4.4.10.2, and isolation requirements for traction batteries were clarified and extended to other power sources (e.g., capacitors) in Section 4.4.10.3. v Requirements for Automatic Disconnects in Section 4.4.11 were clarified to indicate that disconnection of both negative and positive rails is required, and that this function can be achieved by non-mechanical means (e.g., IGBTs). w Requirements for fuel shutoff and electrical disconnect after crash in Section 4.6.2 were clarified, and vehicle labeling of fuel type was simplified and made non-mandatory in Section 4.7. x Maintenance and service intervals were added as recommended information for the Owner’s Manual in Section 5.1, and extensive updates were made to the methods for evaluating normal vehicle discharges (in Sections 5.2.1, 5.2.2, 5.2.3 and Appendix C). y Procedures for defueling were added as recommended information for the Service Manual in Section 7.1, and the rationale for defueling was extended to include damaged vehicles as well as standard service situations in Section 7.2.