UN 3480 and UN 3481: Outer Cartons for Lithium Battery Shipments

The email arrives at 16:40 on a Thursday. Your forwarder's warehouse has pulled 42 cartons of battery packs off the build for tomorrow's flight, because the boxes carry no UN specification mark and the shipment was booked as fully regulated Class 9. The cells are fine. The cushioning is fine. The carton is a good 32 ECT double-wall box that would survive the trip twice over. It is still the wrong box, because "strong enough" and "UN performance tested" are two different legal categories, and only one of them is printed on the side.

Sorting out UN 3480 and UN 3481 outer cartons is mostly a question of deciding which category you are in before you buy 5,000 boxes, not after. The rules are public, stable in structure, and change in detail every year — which is exactly the combination that catches buyers who specified a carton once in 2021 and reordered it ever since.

Four UN numbers, and why only two of them are usually yours

Lithium batteries do not travel under one entry. The number on your dangerous goods declaration decides the packing instruction, and the packing instruction decides the box.

Two more show up at the edges: a separate entry covers batteries installed in a cargo transport unit or battery-powered vehicle, and recent editions of the model regulations have added sodium ion entries that follow a similar structure. Damaged, defective or recalled cells sit under their own rules and are forbidden by air outright — if that is your traffic, the carton is the least of the problem.

Note what UN 3481 does not say. "Contained in equipment" and "packed with equipment" are two different conditions inside the same UN number, with different quantity limits and, in some editions, different documentation. A product whose battery is installed inside the housing and a product shipped with a loose spare in the same retail box are not the same shipment, even though the SKU number is identical.

When the box must carry a UN mark, and when a strong rigid carton is enough

This is the whole decision, and it is worth being blunt about it.

Fully regulated shipments — the higher-energy tiers of the air packing instructions, and non-excepted sea and road movements — require a UN specification packaging tested to Packing Group II performance. That means a design type that has passed the drop and stacking tests behind a packing group rating at an approved laboratory, holds a certificate, and carries the UN mark on the box.

Excepted or lower-tier shipments — the small-cell provisions in the air packing instructions and the equivalent exceptions for sea and road — require a strong rigid outer packaging that can withstand a 1.2 m drop in any orientation without the contents shifting or the package rupturing. No UN mark. No certificate. A well-built double-wall carton with proper cell separation does the job, and paying for a UN box here buys you nothing but a heavier carton.

The thresholds that put you on one side or the other are watt-hour ratings and net quantity per package: for lithium ion, cells above about 20 Wh and batteries above about 100 Wh drop out of the small-cell provisions; for lithium metal it is lithium content per cell and per battery. Read the actual numbers in the edition in force. They are the single most-summarised, most-mis-summarised figures in dangerous goods.

Three things buyers get wrong at this fork:

• The mode changes the answer. The same pallet of packs can be excepted by sea and fully regulated by air. If you flex between ocean and air on the same SKU — and most electronics buyers do — spec the carton for the stricter mode or accept that you own two cartons. Working through how air freight from China is actually booked and surcharged alongside the packing decision saves a re-tool later.
• State of charge is a shipping condition, not a packaging one, and it still lands on your carton. Cells and batteries shipped alone by air are limited to a state of charge of not more than 30%. That is a production and QC instruction: ask your cell supplier for the open-circuit voltage that corresponds to 30% SoC for that chemistry, put the value on the packing inspection sheet, and record the measured voltage on the lot record. Nobody at the airline will measure it, and everybody downstream will ask for the record if something goes wrong.
• Section structures get withdrawn. The lowest tier of the packing instruction for cells and batteries shipped alone has been progressively removed from the air rules. If your compliance file cites a section that no longer exists, your carton spec is orphaned. Re-read the packing instruction each January rather than trusting last year's spec sheet.

Reading the UN mark, and what the certificate behind it actually covers

A UN specification mark on a fibreboard box looks like this:

4G/Y30/S/26/CN/xxxx

Each field is a fact you can check, and the certificate behind it is a document you should be reading rather than filing.

The insider detail is what the mark leaves out. The mark records a design type — a specific board construction, a specific box size, a specific closure, and, critically, the inner packaging and cushioning arrangement that was in the box when it was dropped at the test laboratory. Change the cell tray, swap EPE pearl-cotton for a moulded pulp insert, add a second layer of packs, and you may be outside the tested design type even though the box is physically identical. Ask for the test report, not just the certificate, and check that the inner arrangement described in it is the one you are actually shipping.

Two further checks that separate buyers who have done this before from buyers who have not:

• The closure instruction is part of the approval. A UN design type is tested closed a particular way — tape width, number of strips, H-pattern or single strip, sometimes a specified adhesive. The shipper is required to follow the closure instruction and keep it available. Ask the box maker to supply it as a document, in English, and put it on the pack-out station wall.
• Design types are re-tested on a cycle. In the United States, UN packagings are subject to periodic retesting on a defined interval under 49 CFR 178.601; certifying authorities elsewhere operate their own cycles. A certificate with a five-year-old test date and no retest record is a question, not a disqualification — but it is a question you should ask before the first order, not when a shipment is held.

If the answers arrive as scanned images with no report numbers, treat that the way you would treat any other unverifiable document — the same discipline as reading a Chinese certificate of conformity properly applies here, with higher stakes.

The marks, labels and inner packaging that ride with the box

Getting the outer carton right is roughly half the pack-out. The rest is what goes on it and in it.

On the outside

The lithium battery mark — the red-hatched border with the battery pictogram, the UN number and a telephone number for further information — is required on packages moving under the small-cell provisions, at a nominal size of 120 × 110 mm, with a reduced size permitted where the package is too small to take it. Fully regulated shipments carry the Class 9 lithium battery hazard label, which since 2019 has been a distinct label from the generic Class 9 diamond, plus the UN number, proper shipping name and, by air, a cargo aircraft only label where the packing instruction requires it.

Print those and you have removed a whole category of ramp rejection. A box maker that runs GHS hazard diamonds and handling marks as part of the print pass is doing something useful here: pre-printed marks are legible, consistently placed, and immune to the warehouse running out of label stock at 17:00.

On the inside

Cells must be protected against short circuit and against movement inside the package. In practice that means individual cell separation, terminal protection, and enough cushioning that the pack cannot shift under vibration. EPE pearl-cotton and EVA foam are the usual answers for module and pack shipments; anti-static shielding bags matter where the electronics around the cell are ESD-sensitive rather than for the cells themselves. If you are shipping BMS-populated modules or energy-storage assemblies, the board is often the more fragile item in the box.

One more detail that costs money when missed: the gross mass on the UN mark is a hard ceiling, and cushioning is heavy. A 30 kg design type filled with 26 kg of cells, 2 kg of foam and a 1.6 kg carton is fine; the same design type with a denser insert is not. Weigh a finished, closed, marked package on a calibrated scale during the first article inspection and write the figure on the pack-out spec.

Common questions

Does a UN-marked box make my shipment compliant?

No. The box is one input. The shipment is compliant when the UN number, proper shipping name, packing instruction, quantity limits, state of charge, marks, labels, documentation and the shipper's training are all correct together. A UN box on an incorrectly declared shipment is still an incorrectly declared shipment — it just fails at a different desk. Build the packaging decision into a broader import compliance workflow rather than treating it as a purchasing line item. And treat any box supplier that confidently tells you which packing instruction applies with caution: classification depends on your cell chemistry, watt-hour rating, configuration and mode, and belongs to your dangerous goods advisor or trained shipper. What the box maker owes you is precision about what its own design types cover.

My batteries are inside the product. Do I still need any of this?

Usually yes, in a lighter form. Batteries contained in equipment travel under UN 3481 or UN 3091 and carry their own quantity limits, marks and, depending on tier, documentation. The exceptions are narrower than most consumer-electronics sellers assume, and the fact that a product is sold at retail with a battery inside says nothing about how it may be transported in bulk.

Is a UN box stronger than a good export carton?

Not necessarily. It is proven to a defined performance level, which is different. A heavy-duty double-wall carton may well outperform a 4G design type in a compression test while being useless for a fully regulated shipment. If stacking rather than regulation is your failure mode, the compression and derating arithmetic is the more useful place to spend an hour, and the board grade you specify is the lever.

What to ask your carton supplier next

Send this list before you send a drawing. The answers tell you more about a supplier's dangerous-goods experience than any brochure:

1. Which UN design types are you approved for? List the full codes, including the performance letter and the maximum gross mass in kilograms.
2. Send the test report, not only the certificate. What was the drop height, how many orientations, what conditioning, and what inner packaging and cushioning were in the box during the test?
3. What is the certificate number and the issuing authority, when was the design type tested, and what is the retest cycle?
4. Supply the closure instruction in English, specifying tape type, width and pattern.
5. Can you pre-print the lithium battery mark, Class 9 label area, UN number and handling marks in the same pass as the carton print — and at what colour tolerance?
6. What cushioning can you build to my drawing, and can you supply a first-article sample with the intended inner arrangement so I can weigh a closed, marked package?
7. Are anti-static shielding bags currently available, to what shielding specification, and are they made in-house or bought in?

Jindong Packaging is a fair example of where that list lands. Its CMH listing covers dangerous-goods cartons for hazmat and regulated exports printed with GHS hazard diamonds and handling marks, EPE pearl-cotton and EVA foam cushioning, and anti-static shielding bags flagged as needing confirmation before quoting — from a 12,000 m² plant in Xinqiao, Bao'an, Shenzhen that has been making corrugated packaging since 2007, builds to drawing or sample from 1,000 pieces, and quotes about seven days for sampling and fifteen working days for bulk. The listing also references a dangerous-goods packaging certificate. That reference is the beginning of the conversation, not the end of it: the design type codes, gross-mass ratings, test report and closure instruction are what you need in hand, and asking for them is the same discipline as the wider question of which documents to request before a first order. A supplier that produces them without friction has done this before. One that sends a photograph of a certificate has told you something too.