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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #25-0058

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Invinity Energy Systems

Individual Name: Derek Polman-Tuin

View the Interpretation Document

Response text:

June 10, 2025

Derek Polman-Tuin
Director
Invinity Energy Systems
1250 E. Pender Street
Vancouver, B.C., Canada V6A 1W8

Reference No. 25-0058

Dear Mr. Polman-Tuin:

This letter is in response to your April 23, 2025 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to wet batteries transported via highway. Specifically, you explain that your company designs and manufactures vanadium flow batteries classified as "UN2794, Batteries, wet, filled with acid, electric storage, 8." You state that these batteries contain a non-flammable, aqueous electrolyte solution containing vanadium sulfate. You are seeking confirmation that the transportation of these batteries, as described below and in accordance with the requirements of § 173.159(e), is not subject to any other requirement of the HMR.

  • The battery is shipped fully discharged.
  • The power and energy storage elements (i.e., the tanks) of the battery are physically separated and the power elements (i.e., stacks) contain no stored energy.
  • No voltage on the terminals (0 V).
  • Stacks have no exposed terminals to prevent short circuiting.
  • Stacks are firmly secured within a rigid metal racking system that separates each stack to prevent short circuiting.
  • The metal racking system containing the stacks is firmly secured and integrated into a 20 ft International Organization for Standardization/Convention of Safe Containers (ISO/CSC) certified steel container.
  • The 20-ft ISO/CSC certified container has re-enforced structures, fixtures, and secondary containment.
  • No other hazardous material is shipped with the complete unit.
  • No other materials are transported on the vehicle.

Based on the information as described and the photographs you provided, it is the opinion of this Office that the batteries meet the requirements of § 173.159(e) for highway transport. Please note that batteries transported in this manner are still subject to incident reporting requirements in § 171.15.

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

§ 171.15, § 173.159(e)

Regulation Sections