# Council on the Safe Transportation of Hazardous Articles — Hazardous Materials Safety Interpretation **Citation:** 25-0112 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2026-02-05 25-0112 response to Council on the Safe Transportation of Hazardous Articles concerning 173.185. ## Document text <<>> 1200 New Jersey Avenue, SE Washington, DC 20590 U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration February 5, 2026 Drew Watts Regulatory Compliance Specialist Council on the Safe Transportation of Hazardous Articles 101 Ridge Street, Suite I Glens Falls, NY 12801 Reference No. 25-0112 Dear Mr. Watts: This letter is in response to your July 21, 2025, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the watt-hour (Wh) marking requirement for lithium ion batteries in § 173.185(a)(5). You describe a battery assembly that is comprised of eight lithium ion battery modules. One of the modules is marked with two Wh markings—one indicating the Wh rating of an individual module and the other indicating the total Wh rating of the completed battery assembly (i.e., the eight connected battery modules). Specifically, you ask, in the instance when such a dual-marked module must be transported, whether it is acceptable to cover the marking that reflects the Wh rating for the completed battery assembly prior to transport? Yes. The Wh rating marking required by § 173.185(a)(5) must be representative of the battery being transported. For purposes of the HMR, battery packs, modules, or battery assemblies having the primary function of providing a source of power to another piece of equipment are treated as a battery (see UN Manual of Tests and Criteria, 38.3.2.3). Thus, it is acceptable to transport the dual marked battery module, provided the Wh rating marking that is not representative of the battery is covered during transportation. I hope this information is helpful. Please contact us if we can be of further assistance. Sincerely, Dirk Der Kinderen Chief, Standards Development Branch Standards and Rulemaking Division <<>> Casey, C. 25-0112 President Dan Hankinson Program Manager Stellantis First Vice President Janet Kolodziey-Nykolyn Dir. Global Dangerous Goods Compliance Pfizer, Inc. Second Vice President Carolyn Naumann Dir. Regulatory & Government Affairs US Reckitt Treasurer Veronica Wilson Director, HM Transportation Wal-Mart, Inc Secretary Dave Madsen Reg. Compliance Specialist - Americas Autoliv ASP, Inc. Executive Committee Samuel Moyers Director of Transportation Safety ARCADIS Board of Directors Carla Andrews DG Safety Manager FedEx Logistics Adrienne Mesick DG Process Lead, Lithium Batteries Deere & Company Jon Pelis, DGSA, CDGP EH&S Superintendent The Boeing Company John Redman Sr. Manager, Global Dangerous Goods Compliance General Motors Tim Rogers Director of Air Dangerous Goods UPS Wim Verkuringen Director DG & Transportation Safety Johnson & Johnson Mike Wentz Sr. Specialist Hazmat/DG Compliance American Airlines July 21, 2025 Standards and Rulemaking Division Pipeline and Hazardous Materials Safety Administration Attn: PHH-10 Mr. Matthew Nickels U.S. Department of Transportation East Building, 1200 New Jersey Ave., SE Washington, D.C. 20590-0001 Submitted: Via Email Informal Interpretation Request - Double Watt-Hour Marking for Lithium-Ion Battery Modules per § 173.185(a)(5) Dear Mr. Nickels, On behalf of one of our members, COSTHA would like to request an informal interpretation and helpful guidance regarding the Watt-hour (Wh) marking requirement that is within § 173.185(a)(5), which states: “Beginning May 10, 2024, each lithium-ion battery must be marked with the Watt‑hour rating on the outside case.” Background Information: To add more context, this member produces hybrid electric battery assemblies that are comprised of multiple lithium-ion battery modules. These modules are not fully enclosed within a single outer casing. In their current assembly, there are eight lithium-ion battery modules and one of the lithium-ion battery modules within the assembly is double labeled with: • One mark showing the Watt-hour rating of the individual module itself • The other mark showing the total Watt-hour rating of the overall battery pack or battery assembly When service on these assemblies is required, a single replacement lithium-ion battery module may need to be shipped individually to a dealership for install. In this scenario, the single battery module that is required for shipment could be the module with both Wh ratings marked. COSTHA understands that the intent of § 173.185(a)(5) is to clearly communicate a battery’s nominal energy so shippers and carriers can determine eligibility for small or medium battery exceptions (i.e., ≤100 Wh or ≤300 Wh). In this instance, both the individual battery modules and the overall battery pack or assembly exceed these thresholds for the exceptions. However, we understand that the presence of two different Wh marks on the individually shipped module could potentially mislead carriers or inspectors since the second rating doesn’t represent the actual energy content of the item being shipped. Informal Interpretation Request: To avoid any potential confusion, COSTHA believes it would be acceptable to: Council on Safe Transportation of Hazardous Articles 101 Ridge Street, Suite I, Glens Falls, NY 12801 • Phone: (518)761-0389 • Fax: (518)792-7781 • www.costha.com <<>> • Cover the irrelevant full-assembly Wh mark (with tape or other obscuring method) prior to shipment to dealerships • Direct technicians at dealerships to remove the tape or obscuring method once the module is installed in the battery assembly during servicing We respectfully request your informal interpretation on whether this approach would be compliant with § 173.185(a)(5) when shipping the double marked individual module for servicing needs. If you have any other recommendations to ensure compliance and minimizing mismarking risk at the shipment level, it would be very much appreciated. COSTHA appreciates your time and consideration with this informal request and we look forward to hearing from you soon. Please let us know if you require any additional details to evaluate this request. A diagram illustrating this interpretation request is also attached below for your reference. Sincerely, Drew Watts Regulatory Compliance Specialist COSTHA Attachment 1: Double Wh Marking Compliance Question Illustration Council on Safe Transportation of Hazardous Articles 101 Ridge Street, Suite I, Glens Falls, NY 12801 • Phone: (518)761-0389 • Fax: (518)792-7781 • www.costha.com <<>> Lithium-ion Watt-hour Rating Marking Requirement (USDOT) Current manufacturing practice is that one lithium-ion battery module within the battery assembly is double marked with the module and the full assembly Watt-hour rating (see module H in diagram below). Concern: For service part shipment, can a module be double labeled, if that is the module being replaced by the dealership and still be compliant with USDOT requirement? Council on Safe Transportation of Hazardous Articles 101 Ridge Street, Suite I, Glens Falls, NY 12801 • Phone: (518)761-0389 • Fax: (518)792-7781 • www.costha.com ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `b781697b7e2dbcfd35163b5e5c570ab2a00092e4f8bd6e2ab923b68ce8161ad1` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T04:04:29.515Z - Document slug: `phmsa-interpretation-25-0112` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Council on the Safe Transportation of Hazardous Articles" ], "individuals": [ "Drew Watts" ], "refIds": [ "25-0112" ], "catalogDates": [ "2026-02-05" ], "catalogParts": [ 173 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/82206" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "173.185", "173.185(a)(5)" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/173185" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-02/25-0112.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-02/25-0112.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-02/25-0112.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/25-0112-49997c5a28.pdf", "pdfArtifactSha256": "9ee0594d94715326e312d602979b61dc53ec14acbb8bf92f85b03841dacd9f0f", "extractedTextPath": "data/sources/phmsa-interpretations/25-0112-49997c5a28.v2.txt", "extractedTextSha256": "f18d66c9f72fafa7f87d1ad5f149137e9a973d899eeb89c3bbfb392de7f4fd87", "pageCount": 4, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```