Interpretation Response #25-0112
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: Council on the Safe Transportation of Hazardous Articles
Individual Name: Drew Watts
Location State: NY Country: US
View the Interpretation Document
Response text:
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
Regulation Sections
| Section | Subject |
|---|---|
| 173.185 | Lithium cells and batteries |