Interpretation Response #25-0096
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name: Matson Navigation Co.
Individual Name: James Owen
Location State: AZ Country: US
View the Interpretation Document
Response text:
September 24, 2025
James Owen
Manager Dangerous Goods
Matson Navigation Co.
3426 E Libby St.
Phoenix AZ 85032
Reference No. 25-0096
Dear Mr. Owen:
This letter is in response to your July 15, 2025 email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to lithium battery-powered vehicles. It is your understanding that according to PHMSA's lithium battery guide, vehicles shipped as "UN3171, Battery-powered vehicle or Battery-powered equipment, 9" are excepted from all HMR requirements under § 176.905 with certain conditions. Moreover, you believe that when the International Maritime Dangerous Goods (IMDG) Code introduced "UN3556, Vehicle, lithium ion battery powered, 9" it created a conflict with the aforementioned exception and the stricter requirements for shipment of lithium batteries under § 173.185(c)(1) in the HMR. These stricter requirements only allow shipment under exceptions for lithium ion batteries up to 100 Watt-hours (Wh). You question how vehicles powered by large batteries, such as a particular vehicle with a 123,000 Wh battery, can be excepted from specific requirements while a standalone battery slightly over 100 Wh cannot. Therefore, you seek clarification regarding the differing treatment of lithium ion batteries as a standalone versus vehicle-installed applications under the HMR and IMDG Code regulations.
We have paraphrased and answered your questions as follows:
Q1. How is it possible that a lithium ion battery with a capacity greater than 100 Wh is more regulated than a much larger battery, as in the example given in the letter, which is a component part of a vehicle?
A1. The HMR allows exceptions for certain materials, such as vehicles, based on comparative hazards in transportation. Motor vehicles are subject to vehicle safety standards (e.g., the National Highway Traffic Safety Administration Federal Motor Vehicle Safety Standards). Additionally, the body of a vehicle itself offers protection against damage during normal transportation conditions. Thus, based on certain additional conditions, such as a lithium ion battery that is a component of a motor vehicle being subject to UN 38.3 testing, a vehicle is afforded exceptions from further regulation.
Q2. Given the IMDG Code adoption of the "UN3556" description for a lithium ion battery-powered vehicle, can vehicles consigned under "UN3556" qualify for the exception outlined in Part 3, Chapter 3.3, Special Provision 961.5?
A2. No. Special Provision 961.5 applies to a wet or dry electric storage battery or a sodium battery. A lithium ion battery is neither a wet nor a dry electric storage battery. A lithium ion battery has a distinct battery chemistry due to its chemical composition and associated risks. However, a lithium ion battery-powered vehicle may still be excepted from further regulation in accordance with IMDG Code provision found in 961.1.
Q3. Given that the IMDG Code Special Provision 961 and § 176.905(i) of the HMR have the same language but now that there are differing hazardous material descriptions for lithium ion battery-powered vehicles, how is the exception applied under the HMR?
A3. Domestically, the hazardous material identification number "UN3556" has not yet been formally adopted into the HMR. In general, electric vehicles (i.e., battery-powered vehicles) may be shipped under the existing description as "UN3171," which covers a battery-powered vehicle powered by lithium ion batteries. Furthermore, the HMR allows for the use of international standards, such as the IMDG Code, for domestic transportation under certain conditions outlined in 49 CFR Part 171, Subpart C, and in combination with an enforcement policy notice issued by PHMSA which authorizes use of the current edition of the IMDG Code (Amendment 42-24) that includes the "UN3556" identification number. However, it should be noted that there is no difference in the application of exceptions between the use of "UN3171" and "UN3556" for electric vehicles powered by lithium ion batteries. The new identification number merely provides a more distinct hazardous material description.
Q4. Does PHMSA consider a lithium ion battery to be a dry electric storage battery, and if not, how does a lithium ion battery meet the exception within § 176.905(i)?
A4. No. As stated in answer A2, a lithium ion battery is not considered a dry electric storage battery for purposes of the HMR or the IMDG Code. Furthermore, a lithium ion battery-powered vehicle may still be eligible for exception from regulation in accordance with Special Provision 961.1 or its counterpart in § 176.905(i)(1).
I hope this information is helpful. Please contact us if we can be of further assistance.
Sincerely,
Dirk DerKinderen
Chief, Standards Development Branch
Standards and Rulemaking Division
§ 173.185(c)(1), § 176.905, § 176.905(i)