{"operation":"document","citation":"25-0112","title":"Council on the Safe Transportation of Hazardous Articles — Hazardous Materials Safety Interpretation","source_type":"guidance","agency":"Pipeline and Hazardous Materials Safety Administration","status":"guidance","official":true,"published_on":"2026-02-05","effective_on":null,"summary":"25-0112 response to Council on the Safe Transportation of Hazardous Articles concerning 173.185.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0112.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0112.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0112","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-02/25-0112.pdf","body":"<<<PAGE 1>>>\n\n1200 New Jersey Avenue, SE\nWashington, DC 20590\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\nFebruary 5, 2026\nDrew Watts\nRegulatory Compliance Specialist\nCouncil on the Safe Transportation of Hazardous Articles\n101 Ridge Street, Suite I\nGlens Falls, NY 12801\nReference No. 25-0112\nDear Mr. Watts:\nThis letter is in response to your July 21, 2025, email requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to the watt-hour (Wh) marking\nrequirement for lithium ion batteries in § 173.185(a)(5). You describe a battery assembly that is\ncomprised of eight lithium ion battery modules. One of the modules is marked with two Wh\nmarkings—one indicating the Wh rating of an individual module and the other indicating the\ntotal Wh rating of the completed battery assembly (i.e., the eight connected battery modules).\nSpecifically, you ask, in the instance when such a dual-marked module must be transported,\nwhether it is acceptable to cover the marking that reflects the Wh rating for the completed battery\nassembly prior to transport?\nYes. The Wh rating marking required by § 173.185(a)(5) must be representative of the battery\nbeing transported. For purposes of the HMR, battery packs, modules, or battery assemblies\nhaving the primary function of providing a source of power to another piece of equipment are\ntreated as a battery (see UN Manual of Tests and Criteria, 38.3.2.3). Thus, it is acceptable to\ntransport the dual marked battery module, provided the Wh rating marking that is not\nrepresentative of the battery is covered during transportation.\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nDirk Der Kinderen\nChief, Standards Development Branch\nStandards and Rulemaking Division\n\n<<<PAGE 2>>>\n\nCasey, C.\n25-0112\nPresident\nDan Hankinson\nProgram Manager\nStellantis\nFirst Vice President\nJanet Kolodziey-Nykolyn\nDir. Global Dangerous Goods Compliance\nPfizer, Inc.\nSecond Vice President\nCarolyn Naumann\nDir. Regulatory & Government Affairs US\nReckitt\nTreasurer\nVeronica Wilson\nDirector, HM Transportation\nWal-Mart, Inc\nSecretary\nDave Madsen\nReg. Compliance Specialist - Americas\nAutoliv ASP, Inc.\nExecutive Committee\nSamuel Moyers\nDirector of Transportation Safety\nARCADIS\nBoard of Directors\nCarla Andrews\nDG Safety Manager\nFedEx Logistics\nAdrienne Mesick\nDG Process Lead, Lithium Batteries\nDeere & Company\nJon Pelis, DGSA, CDGP\nEH&S Superintendent\nThe Boeing Company\nJohn Redman\nSr. Manager, Global Dangerous Goods\nCompliance\nGeneral Motors\nTim Rogers\nDirector of Air Dangerous Goods\nUPS\nWim Verkuringen\nDirector DG & Transportation Safety\nJohnson & Johnson\nMike Wentz\nSr. Specialist Hazmat/DG Compliance\nAmerican Airlines\nJuly 21, 2025\nStandards and Rulemaking Division\nPipeline and Hazardous Materials Safety Administration\nAttn: PHH-10\nMr. Matthew Nickels\nU.S. Department of Transportation\nEast Building, 1200 New Jersey Ave., SE\nWashington, D.C. 20590-0001\nSubmitted: Via Email\nInformal Interpretation Request - Double Watt-Hour Marking for Lithium-Ion\nBattery Modules per § 173.185(a)(5)\nDear Mr. Nickels,\nOn behalf of one of our members, COSTHA would like to request an informal\ninterpretation and helpful guidance regarding the Watt-hour (Wh) marking\nrequirement that is within § 173.185(a)(5), which states:\n“Beginning May 10, 2024, each lithium-ion battery must be marked with the\nWatt‑hour rating on the outside case.”\nBackground Information:\nTo add more context, this member produces hybrid electric battery assemblies that\nare comprised of multiple lithium-ion battery modules. These modules are not fully\nenclosed within a single outer casing. In their current assembly, there are eight\nlithium-ion battery modules and one of the lithium-ion battery modules within the\nassembly is double labeled with:\n• One mark showing the Watt-hour rating of the individual module itself\n• The other mark showing the total Watt-hour rating of the overall battery pack\nor battery assembly\nWhen service on these assemblies is required, a single replacement lithium-ion\nbattery module may need to be shipped individually to a dealership for install. In this\nscenario, the single battery module that is required for shipment could be the module\nwith both Wh ratings marked. COSTHA understands that the intent of §\n173.185(a)(5) is to clearly communicate a battery’s nominal energy so shippers and\ncarriers can determine eligibility for small or medium battery exceptions (i.e., ≤100\nWh or ≤300 Wh). In this instance, both the individual battery modules and the overall\nbattery pack or assembly exceed these thresholds for the exceptions. However, we\nunderstand that the presence of two different Wh marks on the individually shipped\nmodule could potentially mislead carriers or inspectors since the second rating\ndoesn’t represent the actual energy content of the item being shipped.\nInformal Interpretation Request:\nTo avoid any potential confusion, COSTHA believes it would be acceptable to:\nCouncil on Safe Transportation of Hazardous Articles\n101 Ridge Street, Suite I, Glens Falls, NY 12801 • Phone: (518)761-0389 • Fax: (518)792-7781 • www.costha.com\n\n<<<PAGE 3>>>\n\n• Cover the irrelevant full-assembly Wh mark (with tape or other obscuring method) prior\nto shipment to dealerships\n• Direct technicians at dealerships to remove the tape or obscuring method once the\nmodule is installed in the battery assembly during servicing\nWe respectfully request your informal interpretation on whether this approach would be\ncompliant with § 173.185(a)(5) when shipping the double marked individual module for servicing\nneeds. If you have any other recommendations to ensure compliance and minimizing\nmismarking risk at the shipment level, it would be very much appreciated.\nCOSTHA appreciates your time and consideration with this informal request and we look\nforward to hearing from you soon. Please let us know if you require any additional details to\nevaluate this request.\nA diagram illustrating this interpretation request is also attached below for your reference.\nSincerely,\nDrew Watts\nRegulatory Compliance Specialist\nCOSTHA\nAttachment 1: Double Wh Marking Compliance Question Illustration\nCouncil on Safe Transportation of Hazardous Articles\n101 Ridge Street, Suite I, Glens Falls, NY 12801 • Phone: (518)761-0389 • Fax: (518)792-7781 • www.costha.com\n\n<<<PAGE 4>>>\n\nLithium-ion Watt-hour Rating Marking Requirement (USDOT)\nCurrent manufacturing practice is that one lithium-ion battery\nmodule within the battery assembly is double marked with the\nmodule and the full assembly Watt-hour rating (see module H in\ndiagram below).\nConcern: For service part shipment, can a module be double labeled,\nif that is the module being replaced by the dealership and still be\ncompliant with USDOT requirement?\nCouncil on Safe Transportation of Hazardous Articles\n101 Ridge Street, Suite I, Glens Falls, NY 12801 • Phone: (518)761-0389 • Fax: (518)792-7781 • www.costha.com","truncated":false,"body_characters":7023}