Shipping Lithium Batteries Internationally: Class 9 Dangerous Goods, the UN38.3 Test Summary & the Documents Your Freight Forwarder Needs

Lithium batteries are classified as Class 9 dangerous goods, which means shipping them across borders is governed by the same regulatory framework as other hazardous materials. Get the classification, packaging, or paperwork wrong and your shipment can be rejected at the dock, offloaded mid-transit, or held by customs — with the cost and delay landing on you, not the carrier.

This guide explains, in plain language, how international lithium battery shipping actually works: which UN number applies to your product, how watt-hours decide the rules, what changed in 2026, and exactly which documents your freight forwarder needs before a single pack moves. If you are an OEM sourcing custom battery packs, this is the knowledge that keeps your supply chain running.

Why lithium batteries are "Class 9 dangerous goods"

Class 9 is the "miscellaneous dangerous goods" category in the UN system — it covers substances that present a transport hazard not falling into the other eight classes. Lithium batteries are here because a damaged, defective, or overcharged cell can enter thermal runaway: a self-sustaining reaction that releases intense heat, gas, and fire that is extremely difficult to extinguish. In a sealed aircraft cargo hold or a stacked sea container, that is a serious risk.

Because of this, lithium battery transport is regulated by mode:

• Air — the ICAO Technical Instructions, operationalized by the IATA Dangerous Goods Regulations (DGR), updated every year.
• Sea — the IMDG Code (International Maritime Dangerous Goods Code) issued by the IMO.
• Road — ADR in Europe and 49 CFR (PHMSA) in the United States.

The golden rule of multimodal shipping: when a shipment crosses modes, the strictest applicable rule wins. Air is almost always the most restrictive, so if any leg of the journey is by air, plan for air rules from the start.

The four UN numbers: which one applies to your shipment?

Every lithium battery in commerce ships under one of four UN numbers. Choosing the right one is the single most important decision — pick the wrong one and you have a misdeclaration before you even reach the packaging stage. The distinction comes down to two questions: lithium-ion or lithium-metal? and shipped alone, or with equipment?

For a typical custom rechargeable pack, you are almost always dealing with lithium-ion — so UN3480 if it ships on its own, or UN3481 if it ships installed in or alongside your device. (Lithium-metal cells, UN3090/3091, are non-rechargeable primary cells and follow a parallel but stricter set of rules.)

One critical air-transport fact: standalone lithium-ion batteries (UN3480) and standalone lithium-metal batteries (UN3090) are forbidden on passenger aircraft entirely. They can only move on cargo aircraft. This is why large battery packs shipped by themselves so often travel by sea or by dedicated freighter.

Watt-hours and lithium content: how your battery's rating decides the rules

Within each UN number, the regulations split into tiers based on energy. For lithium-ion you measure in watt-hours (Wh); for lithium-metal you measure lithium content in grams.

Watt-hours are easy to calculate: Wh = Volts × Amp-hours. A 3.7 V cell rated at 2,500 mAh (2.5 Ah) is 3.7 × 2.5 ≈ 9.25 Wh. A laptop battery is roughly 50–100 Wh; a large industrial pack is often several hundred Wh and well into the fully regulated tier.

The key thresholds that separate "lighter burden" from "fully regulated Class 9":

What the sections mean in practice:

• Section II — small cells/batteries below the thresholds. Lighter paperwork (often no Shipper's Declaration), but quantity caps per package apply, and the standalone-on-passenger-aircraft ban still holds.
• Section IB — small cells/batteries shipped in larger outer packages. Fully regulated, with some relief.
• Section IA — larger cells and batteries. Full Class 9 treatment: UN-specification packaging, the complete Shipper's Declaration, the Class 9 hazard label — the works.

Most custom industrial packs exceed 100 Wh, which puts them squarely in Section IA. Verify the exact Wh rating before assigning a section: misclassifying IA versus IB has direct consequences for which aircraft can carry your shipment.

The UN38.3 Test Summary: the document everything depends on

Before any lithium battery can be transported, the cell and battery must pass UN38.3 — the transport-safety qualification from the UN Manual of Tests and Criteria (eight tests covering altitude, thermal cycling, vibration, shock, short circuit, impact/crush, overcharge, and forced discharge).

Since 2020, manufacturers and distributors have been required to make a UN38.3 Test Summary available. This standardized document lists the cells/batteries covered, the manufacturer, the test lab, and the results. It is the single piece of paper that proves your battery is legal to ship.

For an OEM buyer, the practical takeaway is simple: request the UN38.3 Test Summary from your battery supplier before your first shipment moves. You are responsible for having it available if a carrier or customs authority asks — so make it a condition of your purchase, not an afterthought. A supplier who cannot produce a clean Test Summary covering both the cell and the assembled pack is a supplier who will eventually cost you a held shipment.

What changed in 2026: the IATA DGR 67th Edition

Lithium battery rules tighten every year, and 2026 brought significant changes. The IATA DGR 67th Edition took effect on January 1, 2026, and the parallel IMDG Code Amendment 42-24 became mandatory for sea freight on the same date. The headline updates:

• The 30% State of Charge (SoC) limit is now mandatory, not just recommended. Standalone lithium-ion batteries (UN3480) shipped by air must be at no more than 30% of rated capacity, and the 2026 edition extends a 30% SoC requirement to additional categories (including certain cells/batteries packed with equipment above 2.7 Wh). Shipping above 30% now requires written approval from both the State of Origin and the operator's State (Special Provision A331) and is limited to freighter aircraft. Airlines do spot checks; a pack over the limit is offloaded immediately.
• New shipping entries were introduced, including UN3556 for lithium-ion-battery-powered vehicles above 100 Wh, plus new provisions for sodium-ion batteries.
• The telephone number is no longer required on the lithium battery mark. Marks that still carry a phone number may continue to be used until December 31, 2026.
• New State variations were added — for example, France introduced restrictions targeting lithium batteries not certified to UN38.3, and Thailand now requires English-language package markings plus a 24-hour emergency contact.

If you have been treating the SoC limit as a suggestion, that era is over. Build it into your supplier's shipping specification.

The documents your freight forwarder needs

This is the checklist that prevents rejected shipments. For a fully regulated lithium battery shipment (Section IA/IB), your freight forwarder will typically need:

1. UN38.3 Test Summary — proof the battery passed transport-safety testing (covering both cell and pack).
2. Shipper's Declaration for Dangerous Goods (DGD) — the formal dangerous-goods document stating the UN number, proper shipping name, class, packing instruction, quantity, and packaging. Required for fully regulated shipments.
3. Safety Data Sheet (SDS / MSDS) — the battery's safety datasheet.
4. Air Waybill (AWB) or Bill of Lading with the correct dangerous-goods notation. (For lighter Section II shipments that don't require a full DGD, the forwarder instead adds a lithium-battery statement on the air waybill.)
5. Commercial invoice and packing list — for customs clearance.
6. 24-hour emergency contact number — a reachable contact, complete with international dialing code, that can provide information about the goods in transit.
7. Dangerous-goods packing certificate / declaration, where the carrier or route requires it.

A well-prepared supplier hands most of this over with the shipment. The OEM's job is to make sure the package matches the paperwork — which is where rejections actually happen.

Marks and labels on the package

Documentation is only half the equation; the outer package must be marked and labeled correctly:

• Lithium battery mark — the red-hatched-border mark showing the UN number(s). (As of 2026, a telephone number is no longer required on it.)
• Class 9 lithium battery hazard label — the dedicated Class 9 label with the battery symbol, required for fully regulated shipments.
• Cargo Aircraft Only (CAO) label — required for all Section IA and IB shipments by air, and mandatory whenever the goods are forbidden on passenger aircraft.
• UN-specification packaging marks — for Section IA, the outer packaging itself must be tested and certified to UN standards.

Common reasons lithium battery shipments get rejected

Knowing the failure modes is the fastest way to avoid them. The most frequent causes of rejection at acceptance:

• An unsigned Shipper's Declaration. Forgetting the signature/certification statement is consistently one of the top rejection reasons — a clerical slip that grounds the whole shipment.
• Wrong or missing UN number / proper shipping name (e.g., declaring UN3480 when the battery is actually installed in equipment, which is UN3481).
• Incorrect or missing packing instruction or section (IA vs IB vs II).
• A confusing quantity or packaging description — the declaration must clearly state how many packages, what they are made of, and the net weight of dangerous goods.
• A missing or incomplete 24-hour emergency phone number (no dialing code).
• State of charge above 30% — an immediate offload for air freight.
• No UN38.3 Test Summary available when a carrier or authority asks.

Almost every one of these is preventable with a competent shipper and a supplier who builds compliance in from the start.

How PackForge Energy handles dangerous-goods shipping

We treat shipping compliance as part of the product, not as a problem we hand to the customer at the loading dock. For every order, we:

• Classify the pack correctly under the right UN number and section, based on its watt-hour rating and how it ships;
• Provide the UN38.3 Test Summary and SDS up front, covering both the cell and the assembled pack, so your freight forwarder and compliance team have what they need before the first shipment;
• Ship lithium-ion packs at the required state of charge and in UN-specification packaging with the correct marks and labels;
• Prepare the dangerous-goods documentation so your package and your paperwork match — the single most common point of failure.

The result is fewer held shipments, fewer surprises at customs, and a documentation trail your team can verify independently.

Frequently asked questions

What is the difference between UN3480 and UN3481? UN3480 is for lithium-ion batteries shipped on their own. UN3481 is for lithium-ion batteries packed with, or contained in, equipment. Picking the correct one is essential — declaring the wrong UN number is one of the most common shipping mistakes.

Do lithium batteries always need a Shipper's Declaration? No. Fully regulated shipments (Section IA/IB) require a Shipper's Declaration for Dangerous Goods. Smaller batteries shipped under Section II often do not — but the freight forwarder still adds a lithium-battery statement to the air waybill, and marks/labels are still required.

Can I ship lithium-ion batteries on a passenger plane? Standalone lithium-ion batteries (UN3480) are forbidden on passenger aircraft and must travel on cargo aircraft only. Batteries packed with or contained in equipment (UN3481) can move on passenger aircraft, subject to watt-hour limits and section classification.

Why is there a 30% charge limit for air shipping? A fully charged lithium-ion cell stores more energy and generates more heat if it fails, which is dangerous in an aircraft cargo hold. As of January 1, 2026, the 30% State of Charge limit for standalone lithium-ion batteries by air is mandatory. Shipping above it requires written approval from the State of Origin and the operator's State, on freighter aircraft only.

Is shipping lithium batteries by sea easier than by air? Often, yes, for large packs. The IMDG Code does not impose the 30% SoC limit or the passenger-aircraft ban, so high-capacity packs are frequently shipped by sea. Sea freight still requires Class 9 classification, correct UN numbers, proper packaging, marks/labels, and a dangerous-goods declaration.

Who is responsible for the UN38.3 Test Summary — me or my supplier? Both manufacturers and distributors must make it available, which means it should originate with your battery supplier. As the shipper, you are responsible for having it on hand if a carrier or authority requests it — so request it from your supplier before your first shipment.