The USPS allows limited exemptions for shipping low-capacity lithium batteries without hazardous material labels if they meet specific criteria. Batteries must be ≤2 grams lithium metal (primary) or ≤100 Wh (rechargeable), properly sealed, and packed in non-flammable materials. Devices containing these batteries must be turned off and protected from damage. International shipments require stricter compliance.
How Does USPS Define Low-Capacity Lithium Batteries?
USPS categorizes low-capacity lithium batteries as those containing ≤2 grams of lithium metal (non-rechargeable) or ≤100 watt-hours (rechargeable). This applies to small consumer electronics like watches, calculators, and medical devices. Batteries exceeding these thresholds require full hazardous material labeling and specialized shipping procedures.
The 2-gram lithium metal limit for primary batteries corresponds to approximately 8 grams of lithium-ion equivalent, creating a standardized safety threshold based on extensive thermal runaway testing. This differentiation accounts for the higher energy density in rechargeable systems. For example, a typical lithium cobalt oxide (LiCoO2) cell must stay under 100Wh to maintain stable chemistry during transport vibrations. Manufacturers often certify capacity through UN38.3 testing, which includes altitude simulation, thermal cycling, and impact resistance evaluations. Recent updates to 49 CFR 173.185 clarify that button cells installed in devices require additional conductive material separation to prevent parallel circuiting during transit.
| Battery Type | Maximum Capacity | Common Examples |
|---|---|---|
| Primary (Non-rechargeable) | ≤2 grams lithium metal | CR2032 coin cells, AA lithium batteries |
| Rechargeable | ≤100 watt-hours (Wh) | Smartphone batteries, laptop batteries |
What Packaging Requirements Apply to Exempt Lithium Batterings?
Exempt batteries must be:
- Fully enclosed in original retail packaging or non-conductive material
- Protected from short-circuiting (terminal covers recommended)
- Surrounded by cushioning material in rigid outer packaging
- Marked “Consumer Commodity” if shipping internationally
Which Lithium Battery Types Qualify for USPS Label Exemptions?
Exemptions apply to:
- CR2032 coin cells (common in car key fobs)
- AA/AAA lithium primary batteries
- Smartphone batteries ≤100 Wh
- Laptop batteries ≤100 Wh
- Embedded batteries in operational medical devices
Southwest Airlines Lithium Policy
Why Do Some Lithium Shipments Still Require Hazard Labels?
Labels remain mandatory for:
- Batteries exceeding capacity limits
- Damaged/defective units
- Bulk shipments (≥2 batteries not installed in devices)
- Air transport requiring IATA compliance
- Commercial quantities requiring UN38.3 certification
How Does International Shipping Affect Exemptions?
While USPS domestic rules allow exemptions, international shipments through Priority Mail International require:
- Lithium content markings on outer packaging
- Special handling codes (LZ-xxxx)
- Prohibition of loose batteries in mailstream
- Additional documentation for high-risk destinations
What Are Common Mistakes in Shipping Exempt Batteries?
Frequent errors include:
- Mixing exempt/non-exempt batteries in same package
- Using damaged retail packaging
- Failing to secure battery terminals
- Omitting return addresses on small parcels
- Assuming all lithium-polymer batteries qualify
Many shippers underestimate the importance of terminal protection, leading to preventable incidents. In 2022, USPS reported 147 lithium-related package incidents where improperly covered terminals contacted metal objects within mail trucks. A common oversight involves using tape that loses adhesion under temperature fluctuations – spring-loaded terminal covers provide more reliable protection. Additionally, international shipments often get returned due to incomplete “Consumer Commodity” markings, which must be at least 120mm x 110mm on the address side. Proactive measures include using USPS-recommended dielectric gel for exposed contacts and conducting pre-shipment conductivity tests with multimeters to verify isolation.
| Mistake | Risk | Prevention Tip |
|---|---|---|
| Mixing battery types | Package rejection or hazardous incident | Ship different battery types in separate packages |
| Damaged packaging | Short circuits or thermal events | Use new cushioning materials and inspect before shipping |
Expert Views
“The exemption thresholds create a false sense of security. We’ve seen thermal runaway incidents even with ‘exempt’ batteries when improper packaging combines with environmental stressors. Always treat lithium batteries as potential hazards regardless of size.”
– Senior Logistics Safety Officer, Battery Transport Alliance
Conclusion
USPS exemptions for low-capacity lithium batteries require strict adherence to capacity limits, packaging standards, and operational conditions. While the label waiver simplifies domestic shipping, international rules and air transport impose additional layers of compliance. Regular consultation of USPS Publication 52 remains critical as regulations evolve with battery technology advancements.
FAQs
- Can I Ship Lithium Batteries in Envelopes?
- No. All lithium batteries require rigid packaging meeting USPS 3A/3B standards, even when exempt from labeling.
- Do Exemptions Apply to Lithium Batteries in Checked Luggage?
- USPS exemptions don’t cover air travel baggage. FAA regulations prohibit lithium batteries in checked luggage regardless of capacity.
- How Many Exempt Batteries Can I Mail Together?
- USPS allows maximum 2 properly installed batteries per device. Loose batteries require individual packaging regardless of exemption status.