Battery Transport Regulations: What Must Travel With the Battery
A battery is stored energy, and stored energy is a hazard in transit. That single fact governs everything about shipping one: the classification, the packaging, the paperwork — and the penalties for getting any of it wrong.
Why batteries are dangerous goods at all
Transport regulators care about three things in a battery: it can leak corrosive electrolyte (lead-acid), it can short-circuit and overheat (any chemistry), and a damaged lithium cell can enter thermal runaway — a self-sustaining fire that ordinary aircraft fire suppression cannot reliably stop. That is why lithium air transport carries special restrictions, and why the classification system exists in the first place.
Class 8 vs Class 9: the two battery regimes
| Wet lead-acid | Lithium (all chemistries) | |
|---|---|---|
| Hazard class | Class 8 — corrosive | Class 9 — miscellaneous dangerous goods |
| UN numbers | UN 2794 (filled with acid); UN 2800 (non-spillable) | UN 3480 (Li-ion), UN 3090 (Li-metal); UN 3481/3091 when contained in or packed with equipment |
| Key requirement | Non-spillable design and packaging test; upright and short-circuit protection | UN 38.3 test + test summary; SOC limits for air |
UN numbers are the universal identifiers in transport documents — the shipper's declaration names the UN number and class, and the rest of the chain relies on that entry being correct.
UN 38.3: the lithium gatekeeper
Before a lithium cell or battery may be transported, it must pass the UN 38.3 test sequence from the UN Manual of Tests and Criteria: altitude simulation, thermal cycling, vibration, shock, external short circuit, impact/crush, overcharge and forced discharge. The sequence is designed to prove the design survives transport stress without venting, rupture or fire. Since 2020, a test summary must be available for every lithium shipment — one of the documents a serious buyer asks for with the quotation, before the goods are on the water.
The air transport special case
Air freight is where lithium gets strictest. Lithium-ion cells and batteries travel by air only at 30% state of charge or less (with narrow exceptions), because a charged cell holds more energy and sits closer to the runaway threshold. Passenger-aircraft carriage of bare lithium cells and batteries is banned entirely; equipment containing them is permitted within quantity limits. The practical effect: your supplier's discharge practice before packing is now a compliance variable, worth a line in the QC checklist rather than an assumption.
The lead-acid route: non-spillable and proud of it
Wet lead-acid batteries ship under the Class 8 corrosive regime unless they qualify as non-spillable (UN 2800): the electrolyte is absorbed or immobilised — as in AGM and gel designs — and the battery passes a vibration and pressure-differential test. Non-spillable batteries face lighter packaging and documentation duties than their free-acid cousins. The battery's own construction therefore decides the paperwork: another reason the chemistry and design details in the datasheet matter before the logistics conversation starts.
What procurement buyers should check
- Does the quotation state the UN number and class for the exact battery being ordered — not a generic "lithium battery" line?
- For lithium: is the UN 38.3 test summary provided with the quotation, and is it for the actual cell model in the pack?
- For air freight: is the supplier's 30% SOC discharge practice confirmed in writing, before the freight is booked?
- For lead-acid: is the battery non-spillable (UN 2800) — and is the test documentation available — or will it travel as Class 8 corrosive at higher cost and restriction?
- Does the Incoterm and freight forwarder line up with the dangerous-goods rules — see MOQ, payment and Incoterms?
- Are packaging and labelling (orientation arrows, short-circuit protection) part of the supplier's obligations, verified at shipment inspection?
- Is the destination country's import regime (permitted chemistries, certification demands) checked before the goods move?
Frequently asked questions
Are batteries dangerous goods for transport?
Yes, in almost every case. Wet (filled) lead-acid batteries are Class 8 corrosive dangerous goods; lithium batteries are Class 9 miscellaneous dangerous goods. Both travel under UN numbers, packaging rules and carrier restrictions — shipping a battery without the correct classification and paperwork is a compliance breach, not a detail.
What is UN 38.3 and when is it required?
UN 38.3 is the test sequence in the UN Manual of Tests and Criteria that lithium cells and batteries must pass before transport: altitude simulation, thermal cycling, vibration, shock, external short circuit, impact/crush, overcharge and forced discharge. A test summary document must accompany lithium batteries since the 2020 IMDG/IATA requirements.
Why is state of charge restricted for air transport of lithium batteries?
A lithium-ion cell stores more energy when fully charged, and a fully charged cell is closer to thermal runaway conditions in an incident. Air transport regulations therefore cap lithium-ion cells and batteries at 30% state of charge (with limited exceptions), reducing the energy available if something goes wrong.
Sources
Transport classification and requirements cross-checked from the UN model regulations and modal codes; no quoted figures beyond the regulatory limits themselves, which carry their source.
- UN Model Regulations and the UN Manual of Tests and Criteria — Class 8/9 classification, UN numbers, UN 38.3 test sequence.
- IATA Dangerous Goods Regulations (air) — 30% SOC limit and passenger-aircraft restrictions for lithium.
- IMDG Code (sea) and ADR (road) — modal requirements, including the 2020 lithium test-summary obligation.
- Cross-references: Thermal runaway, Safety basics, MOQ, payment and Incoterms.
Part of the Battery Basics 101 series · Last reviewed: 2026-09-24