How full a lithium battery is, as a percentage of capacity. For air transport, lithium-ion cells and batteries shipped on their own (UN3480) must be at 30% state of charge or less — a hard acceptance rule aimed at reducing fire risk in the hold. Shipping at a lower charge is a compliance requirement, not a preference, and carriers will reject over-charged batteries at the counter.
Full guideShipping lithium batteries: UN3480, UN3481 and the rules that trip people up →