Why Lithium Battery State of Charge Matters: The 30% Rule and Beyond

One of the most well-known lithium-ion battery transport regulations is the 30% state-of-charge rule, mandated by the International Civil Aviation Organization (ICAO). This rule is based on the fact that lower charge levels reduce the risk of thermal runaway.

But is this rule enough? And why do industry experts still push for stronger packaging regulations despite this limit?

Why the 30% Rule Exists

Lithium-ion batteries are safest when they contain less stored energy. ICAO determined that at or below 30% charge, batteries:

• • Have less stored energy, reducing fire risk.
• • Generate less heat in case of failure.
• • Are more stable during transport.

While effective, the rule has limitations, which is why the SAE G27 Lithium Battery Packaging Performance Committee is working to improve transport safety.

Why Additional Packaging Standards Are Still Needed

• • Not all batteries can be verified at 30% charge (e.g., distributors reselling used batteries).
• • Some batteries must be shipped fully charged (e.g., medical devices).
• • Packaging ensures safety regardless of charge level.

Conclusion

The 30% rule helps, but stronger packaging solutions are necessary to ensure comprehensive lithium battery safety. The G27 standard is the next step in making global battery transport safer.