{"operation":"document","citation":"25-0102","title":"Currie Associates, Inc. — 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":"25-0102 response to Currie Associates, Inc. concerning 173.185.","machine_formats":{"json":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0102.json","markdown":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0102.md"},"app_url":"https://regulus.evalyn.ai/document/phmsa-interpretation-25-0102","source_url":"https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/2026-02/25-0102.pdf","body":"<<<PAGE 1>>>\n\nU.S. Department\nof Transportation\nPipeline and Hazardous\nMaterials Safety\nAdministration\nFebruary 5, 2026\nAna Diaz\nRegulatory Compliance Specialist\nCurrie Associates, Inc.\n101 Ridge Street Suite I\nGlens Falls, NY 12801\nReference No. 25-0102\nDear Ms. Diaz\nThis letter is in response to your July 22, 2025 letter requesting clarification of the Hazardous\nMaterials Regulations (HMR; 49 CFR Parts 171-180) applicable to size limits for lithium ion\nbatteries with respect to exceptions for smaller cells or batteries and prior clarification\nprovided in a previous letter of interpretation (Reference No. 15-0009).a You indicate that the\ndefinitions section in 38.3.2.3 of the Eighth Revised Edition of the United Nations (UN)\nManual of Tests and Criteria (MTC) now defines a battery as “two or more cells or batteries\nwhich are electrically connected together and fitted with devices necessary for use...” Given\nthis revised definition, you are seeking confirmation that: (1) a lithium ion battery consisting\nof two cells, each exceeding 20 watt-hours (Wh) but with a combined total of less than 100\nWh, qualifies for the exception outlined in § 173.185(c)(1)(i); and (2) the prior clarification\nremains valid.\nYes, your understanding is correct. Furthermore, the letter of interpretation (Ref. No. 15-\n0009) cited in your incoming letter remains valid. PHMSA can confirm that the 100 Wh limit\napplies to the assembled battery, and that the 20 Wh limit for individual cells does not need to\nbe considered for the component cells within that battery. While it is accurate that the UN\nMTC has updated the definition of a “battery,” this revised definition does not invalidate the\n2015 letter of interpretation. If the assembled battery’s total energy density is under 100 Wh,\n1200 New Jersey Avenue, SE\nWashington, DC 20590\na Reference No. 15-0009\n\n<<<PAGE 2>>>\n\nthe exceptions specified in § 173.185(c)(1)(i) apply, even if each component cell exceeds the\n20 Wh limit.\nI hope this information is helpful. Please contact us if we can be of further assistance.\nSincerely,\nDirk DerKinderen\nChief, Standards Development Branch\nStandards and Rulemaking Division\n\n<<<PAGE 3>>>\n\nBaker, Y.\n25-0102\nJuly 22, 2025\nMr. Matthew Nickels\nActing Director, Standards and Rulemaking Division\nPipeline and Hazardous Materials Safety Administration\nAttn: PHH-10\nU.S. Department of Transportation\nEast Building, 1200 New Jersey Ave., SE\nWashington, D.C. 20590-0001\nSubmitted: Via Email\ncc: infocntr@dot.gov\nDear Mr. Nickels:\nCurrie Associates would like to request a formal letter of interpretation regarding the standing\ninterpretation of Letter of Interpretation (LOI) 15-0009. Specifically, we would like to confirm that\nthe interpretation provided by the LOI 15-0009 regarding clarification on the size limits under the\nexception §173.185(c)(1)(i) for lithium ion batteries, applies to a lithium ion battery comprised of\ntwo cells that are greater than 20 Wh each, together forming a battery that is less than 100 Wh.\nCurrie Associates requests this interpretation to confirm our understanding that the\ninterpretation indicated in LOI 15-0009 is still valid given the progression in time and the\nupdated definition for “battery” in the UN Manual of Tests and Criteria.\nLetter of Interpretation 15-0009 states:\nSection §173.185(c)(1)(i) states that the Wh rating may not exceed 20 Wh for a lithium\ncell or 100 Wh for a lithium ion battery. The United Nations (UN) Manual of Tests and\nCriteria defines a battery as “one or more cells which are electrically connected together\nby permanent means.” The 100 Wh size limit applies to your battery irrespective of\nwhether the component cells exceed the 20 Wh rating for a cell. Therefore, the\nexceptions in §173.185(c)(1)(i) apply to your lithium ion battery configuration [81.4 Wh\nbattery comprised of two individual 40.7 Wh cells] since the battery does not exceed 100\nWh.\nThe UN Manual of Tests and Criteria has since updated the definition of “battery” to “two or\nmore cells or batteries which are electrically connected together and fitted with devices\nnecessary for use…”\nBased on the information provided in LOI 15-0009, §173.185(c)(1)(i), and the UN Manual of\nTests and Criteria, Currie Associates understands that the size limits under the exception\n§173.185(c)(1)(i) for lithium ion batteries would include a lithium ion battery comprised of two\n101 Ridge Street Suite I, Glens Falls, NY 12801 | Phone: 1-518-761-0668 | mail@currieassociates.com\n\n<<<PAGE 4>>>\n\ncells, each greater than 20 Wh, that form a battery that is less than 100 Wh; however, we would\nlike an updated letter of interpretation to confirm that our understanding is correct.\nCurrie Associates appreciates your review of this interpretation request, and we look forward to\nhearing from you soon.\nSincerely,\nAna Diaz\nRegulatory Compliance Specialist\nCurrie Associates\nwww.currieassociates.com\nana@currieassociates.com\nO: 518-761-0668\n101 Ridge Street Suite I, Glens Falls, NY 12801 | Phone: 1-518-761-0668 | mail@currieassociates.com\nPage 2 of 2","truncated":false,"body_characters":5058}