Rechargeable, silver-zinc battery
Pipeline and Hazardous Materials Safety Administration · Oct 29, 2007 · Reference No. 07-0152
Interprets: 49 CFR § 173.185
Reggie’s quick take
A company asked whether its rechargeable silver-zinc batteries can be treated as "dry" batteries, like nickel-cadmium batteries, under the Hazardous Materials Regulations and international dangerous goods rules. PHMSA said yes. If the batteries are securely packaged and shipped in a way that prevents dangerous heat buildup and protects against short circuits, as Special Provision 130 requires, they are not subject to any other HMR requirements. International air and vessel shipments must instead meet Special Provision A123 of the ICAO Technical Instructions or Special Provision 304 of the IMDG Code.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This responds to your electronic mail regarding the applicability of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) to your company's rechargeable, silver-zinc battery. You ask whether these batteries should be regulated as "dry" batteries (similar to nickel-cadmium batteries) under the HMR and the various international dangerous goods regulations.
Your understanding is correct. Your classification of the batteries was recognized in a July 24, 2007 meeting with Office of Hazardous Materials Safety staff members. Provided your batteries are securely packaged and offered for transportation in a manner that prevents the dangerous evolution of heat and protects against short circuits, as provided in Special Provision 130, they are not subject to any other requirements of the HMR. For international air and vessel transportation, your battery shipments must conform to Special Provision A123 in the International Civil Aviation Organization Technical Instructions on the Transport of Dangerous Goods and Special Provision 304 of the International Maritime Dangerous Goods Code, respectively.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.