Lithium batteries are Class 9 dangerous goods, and whether yours can fly, on what aircraft, and under which rules comes down to four things about the batteries themselves.
Most guides on this subject say the rules are complex and recommend professional advice. They are complex, but the classification path is not. Work through the four questions below and you will know which entry applies before you speak to anyone.
Can You Ship Lithium Batteries by Air?
Yes, with one restriction that catches most first-time shippers. Lithium batteries shipped on their own are forbidden as cargo on passenger aircraft. They travel on freighter aircraft only, and every package must carry a Cargo Aircraft Only label.
Batteries packed with equipment, or installed inside equipment, can travel on passenger aircraft within the applicable limits.
That single distinction explains most refused bookings. A shipment of loose cells is not restricted on passenger aircraft, it is forbidden, and no amount of packaging or paperwork changes it. The same now applies to sodium ion batteries shipped alone.
What Four Things Decide How Your Batteries Ship?
Chemistry, rating, packing form and quantity. Answer these four and you have the UN number, the Packing Instruction and the carriage route.
- What chemistry are they? Lithium ion, lithium metal or sodium ion
- What is the rating? Watt hours for lithium ion and sodium ion, grams of lithium for lithium metal
- How are they packed? On their own, packed alongside equipment, or installed inside equipment
- How much is in the package? This sets whether the reduced provisions are available
Everything else follows from those answers. The sections below take each one in turn.
What Is the Difference Between Lithium Ion and Lithium Metal?
Lithium ion batteries are rechargeable and contain lithium only in ionic form within the electrolyte. Lithium metal batteries are generally non-rechargeable and contain metallic lithium. They are regulated separately because they behave differently in a fire.
Lithium ion covers lithium polymer as well, and powers phones, laptops, power tools and e-bikes. Lithium metal is the primary cell in watches, calculators, key fobs and medical devices.
The practical difference is how they are measured. Lithium ion is rated in watt hours, printed on most cells and batteries. Lithium metal is measured by the grams of lithium it contains, which is not usually printed and has to come from the manufacturer or the UN 38.3 test summary.
Sodium ion is a third chemistry, now regulated in its own right, covered further down.
What Do UN3480, UN3481, UN3090 and UN3091 Mean?
Each UN number combines a chemistry with a packing form. There is no separate number for size, because size is handled inside the Packing Instruction rather than by the UN number.
| UN number | What it covers | Packing Instruction |
|---|---|---|
| UN3480 | Lithium ion batteries shipped alone | PI 965 |
| UN3481 | Lithium ion packed with or contained in equipment | PI 966 and PI 967 |
| UN3090 | Lithium metal batteries shipped alone | PI 968 |
| UN3091 | Lithium metal packed with or contained in equipment | PI 969 and PI 970 |
| UN3551 | Sodium ion batteries shipped alone | PI 976 |
| UN3552 | Sodium ion packed with or contained in equipment | PI 977 and PI 978 |
Note the pattern. The lower number in each pair is the loose battery and the higher number covers equipment. The loose battery entries are the ones forbidden on passenger aircraft.
Battery-powered vehicles are separate again, under UN3171, UN3556, UN3557 and UN3558 depending on chemistry, with PI 952 governing them.
What Is the Difference Between Section I and Section II?
Section I is the fully regulated route. Section II is a reduced-requirement route available to smaller batteries. Which one applies depends on the rating of the individual cell or battery, not on the size of the shipment.
| Chemistry | Section II available when | Section I applies when |
|---|---|---|
| Lithium ion | Cells 20 Wh or less and batteries 100 Wh or less | Cells above 20 Wh or batteries above 100 Wh |
| Lithium metal | Cells 1 g lithium or less and batteries 2 g or less | Cells above 1 g or batteries above 2 g |
| Sodium ion | Cells 20 Wh or less and batteries 100 Wh or less | Cells above 20 Wh or batteries above 100 Wh |
Section I requires UN specification packaging, full hazard communication and a shipper’s declaration. Section II drops the declaration and the specification packaging, with lower quantity limits per package in exchange.
Two points are widely misunderstood. Section II shipments are still dangerous goods, still subject to occurrence reporting, and anyone handling them must receive documented instruction even where full DGR training is not required. And Section II is not a choice. If the rating exceeds the threshold, Section I applies whether or not the shipment is small.
Figures here come from IATA’s published lithium battery guidance. Confirm them against the current DGR edition before shipping, because thresholds and limits are revised between editions.
Why Are Loose Batteries Forbidden on Passenger Aircraft?
Because a lithium battery fire in a cargo hold cannot reliably be suppressed by the systems fitted to passenger aircraft. A pallet of loose cells concentrates that risk in a way that batteries inside equipment do not.
The prohibition covers UN3480, UN3090 and UN3551, the three loose-battery entries. Packages must be labelled Cargo Aircraft Only and travel on freighters.
Narrow exceptions exist with written approval from the State of Origin and the State of the Operator, under specific special provisions. These are case-by-case approvals rather than a route a shipper can plan around at booking stage.
In practice this is a routing constraint before it is a compliance one. A lane served only by passenger belly capacity cannot carry loose batteries at all, which may mean a longer routing, a freighter service, or in some cases an air cargo charter. Check this before quoting a transit time, because it changes the available services rather than just the paperwork.
What Is State of Charge and Why Does It Matter Now?
State of charge is how full the battery is as a percentage of its rated capacity. Lithium ion and sodium ion batteries shipped alone must be at 30 percent of rated capacity or below.
This changed recently and a lot of published guidance is now out of date. The 30 percent limit moved from a recommendation to a requirement on 1 January 2026, at the end of a twelve month transition under the 2025 to 2026 ICAO Technical Instructions.
The current position runs as follows.
- Shipped alone. Mandatory at 30 percent or below for lithium ion and sodium ion
- Packed with equipment. Mandatory at 30 percent or below for Section I, and for Section II cells and batteries rated above 2.7 Wh
- Contained in equipment. Strongly recommended at 30 percent, not mandatory
- Powering a vehicle. Mandatory at 30 percent, or 25 percent indicated capacity, above 100 Wh
Shipping above 30 percent requires approval from both the State of Origin and the State of the Operator, granted under their own written conditions.
If your supplier ships batteries at full charge as standard, this is the conversation to have before the first booking rather than after the first rejection.
What About Sodium Ion Batteries?
Sodium ion batteries are now regulated in their own right, under UN3551 and UN3552, with sodium ion powered vehicles under UN3558. They were brought into the regulations with the current cycle.
They follow the lithium ion pattern closely. The same watt hour thresholds, the same 30 percent state of charge requirement, and the same prohibition on passenger aircraft when shipped alone.
One difference is worth noting. The limited exceptions that exist for lithium powered tracking devices do not extend to sodium ion devices.
Most published guidance on battery shipping predates these entries and does not mention sodium ion at all. If a forwarder or supplier tells you sodium ion is unregulated because it is not lithium, that advice is out of date.
What Marking and Documents Are Required?
Marking and documentation depend on the section. Section I needs the full set including a shipper’s declaration for dangerous goods. Section II needs the lithium battery mark and the handling information but not the declaration.
Across both, four things travel with the shipment.
- The lithium battery mark on the outer package, showing the UN number
- The Class 9 lithium battery hazard label, where the section requires it
- The Cargo Aircraft Only label on any loose battery shipment
- The UN 38.3 test summary, which manufacturers and distributors must make available, and which can be supplied digitally such as through a QR code
The test summary is the one most often missing. It is the evidence that the cell or battery passed the UN transport tests, and without it the shipment has no basis for classification at all. Request it from the manufacturer at the point of purchase rather than at the point of shipping.
The battery details do not appear on the air waybill itself, which describes the consignment. They sit in the dangerous goods documentation that accompanies it. See air freight documents for how the full set fits together.
What Gets a Lithium Battery Shipment Refused?
Five things account for most refusals, and the first two are absolute rather than correctable.
- Defective, damaged or recalled batteries. Forbidden for air transport outright. Reverse logistics programmes must give consumers a non-air route
- Loose batteries booked on a passenger service. Forbidden, not restricted
- State of charge above 30 percent without the required State approvals
- No UN 38.3 test summary, which leaves the classification unsupported
- Marking or labelling errors, most often a missing Cargo Aircraft Only label or the wrong UN number on the mark
Items three to five are correctable, at the cost of the delay. The shipment sits at the terminal while the paperwork is fixed, which is the common pattern described in air freight transit times.
Items one and two are not correctable. The cargo does not fly.
Who Is Responsible for Classifying the Batteries?
The shipper. Classification is a statement about the goods, and only the party who owns them knows the chemistry, the rating and the condition of what is in the box.
A forwarder can check that the paperwork is consistent and that the booking matches the declaration. It cannot verify that the cells in the carton are what the declaration says they are, and it has no basis to.
This matters more with batteries than with most commodities, because the information often sits with a manufacturer rather than with the shipper. If you are reselling or drop-shipping batteries you did not manufacture, the test summary and the rating data have to come up the chain to you before you can classify anything.
Training is a requirement rather than a recommendation. Where full DGR training does not apply, employers must still document that staff received adequate instruction, and refresh it at least every two years or whenever the regulations change. A good freight forwarder will ask who in your business is trained before accepting the first booking.
For the wider framework these rules sit inside, see dangerous goods by air. For what happens to the cargo physically once it is accepted, see air cargo handling.
Questions About Shipping Lithium Batteries by Air
Can lithium batteries go on passenger planes?
Not when shipped on their own. UN3480, UN3090 and UN3551 are forbidden as cargo on passenger aircraft and must travel on freighters with a Cargo Aircraft Only label. Batteries packed with or inside equipment may travel on passenger aircraft within the limits.
What is the difference between UN3480 and UN3481?
Packing form. UN3480 covers lithium ion batteries shipped on their own. UN3481 covers the same batteries packed alongside equipment or installed inside it. The chemistry is identical, the carriage rules are not.
What is the state of charge limit for shipping lithium batteries?
Thirty percent of rated capacity for lithium ion and sodium ion batteries shipped alone, mandatory since 1 January 2026. Higher states of charge need approval from both the State of Origin and the State of the Operator.
Do I need a shipper’s declaration for lithium batteries?
For Section I shipments, yes. Section II shipments do not require one, though they still need the lithium battery mark, the handling information and documented staff instruction.
Can I ship damaged or recalled lithium batteries by air?
No. Defective, damaged and recalled batteries are forbidden for air transport. They have to move by another mode, and recall programmes must give consumers a non-air return route.
What is a UN 38.3 test summary and do I need one?
It is the record that a cell or battery passed the UN transport tests, and manufacturers and distributors must make it available. Without it a shipment has no supported classification. It can be supplied digitally, including by QR code.
