Understanding the smaller lithium battery exception
Lithium batteries are everywhere, and they’re one of the most shipped hazardous materials today. They’re also one of the most misunderstood. These batteries can enter thermal runaway if damaged, short-circuited, or improperly packaged, which is a risk that has led to continuous updates in the Hazardous Materials Regulations (HMR). These updates are intended to reinforce compliance and prevent incidents that could result in fires or other serious hazards.
Between the exception in 49 CFR 173.185(c) and evolving safety requirements, it’s easy for shippers and transporters to get tripped up. This article breaks down what you need to know about the lithium battery exception and the Pipeline and Hazardous Materials Safety Administration (PHMSA) guidance, without overwhelming you with regulatory jargon.
What does the 173.185(c) exception do?
The lithium battery exception in 173.185(c) offers relief for smaller lithium-ion and lithium-metal batteries that meet specific watt-hour or lithium content thresholds. When eligible, shippers may be exempt from certain marking, labeling, packaging, and shipping paper requirements.
However, these batteries are not fully exempt. Even under the exception, they must:
- Be packaged in a strong outer container,
- Be protected against short circuits and damage, and
- Display the lithium battery mark on the package.
PHMSA's guidance
PHMSA’s Lithium Battery Guide for Shippers is a practical resource that explains requirements based on how batteries are shipped: alone, with equipment, or contained in equipment. Key points include:
- Some transport modes, such as air and vessel, still require documentation even when the exception applies.
- International or vessel shipments may trigger additional IMDG Code requirements.
- The guide clarifies when shipping papers, marks, and labels are required despite exception status.
Remember: the guide simplifies compliance, but it does NOT replace the HMR. If there’s a conflict, the regulation wins.
Common misunderstandings
- “Small lithium batteries don’t need any paperwork.” Not always true. Air carriers and vessel transport often require documentation or additional hazard communication, even for excepted batteries.
- “If it meets the exception, packaging doesn’t matter.” Incorrect. Many lithium battery fires have involved damaged or poorly packaged cells. Exception or not, packaging must prevent short circuits, movement, and damage.
- “The rules rarely change.” PHMSA continues to refine lithium battery requirements, including rule changes and updated guidance to address incident trends and industry growth.
Tips for compliant shipping
- Know your numbers: Verify watt-hour or lithium content ratings before applying the exception.
- Check the mode: Ground shipments often enjoy the most relief; air and vessel shipments are stricter and may impose additional requirements.
- Use PHMSA’s guide: It’s your best resource for understanding scenario-specific requirements.
Key to remember: Lithium battery technology is constantly changing and so are the regulations. The key is understanding when the 173.185(c) exception applies, what it does not eliminate, and how PHMSA’s guidance can help you navigate real-world shipping scenarios.














































