Lithium batteries are dangerous goods. That single fact means a container of LFP cells cannot move on a commercial invoice alone. Five documents are required, every time, for every destination. Four of them you can prepare in advance. The fifth depends on a test report you may not have, and it is the one that stops shipments.
1. UN38.3 Test Summary — the One You Cannot Fake
UN38.3 is the UN transport test series for lithium cells and batteries: altitude simulation, thermal test, vibration, shock, external short circuit, impact, overcharge and forced discharge. Every cell type and every battery pack design must pass it, and the test summary must be available on request.
Two things go wrong here constantly. First, a supplier sends the cell manufacturer’s UN38.3 report and assumes it covers the finished pack. It does not — a pack built from tested cells is a new article and needs its own report. Second, the report exists but the model number on it does not match the model number on the invoice. Customs officers check this, and a mismatch is treated as no report at all.
- What you need: UN38.3 test summary covering the exact pack model being shipped, issued by an accredited third-party lab.
- Valid for: the life of the design. If the BMS or cell supplier changes, it needs re-testing.
- Common failure: model number mismatch between report, invoice and packing list.
2. MSDS / SDS — Fourteen Sections, Not Two Pages
The Safety Data Sheet must follow the 16-section GHS format. A two-page supplier datasheet with a red flammable label is not an MSDS and will be rejected.
Section 14 is the one customs reads first: it must state the UN number, proper shipping name, hazard class and packing group. Section 9 (physical and chemical properties) and Section 3 (composition) are read when a customs officer wants to verify that what is in the box matches what is on the paper.
| Section | What customs checks | Common error |
|---|---|---|
| 3 — Composition | Cell chemistry matches the declared UN number | Says “lithium ion” with no cathode chemistry |
| 9 — Properties | Nominal voltage, energy in Wh per unit | Energy stated in Ah only, no Wh |
| 14 — Transport | UN number, proper shipping name, class, packing group | UN3480 declared for a pack that should be UN3481 |
| 15 — Regulatory | Relevant transport regulations cited | Blank, or cites a withdrawn edition |
3. The Correct UN Number — UN3480 or UN3481
This is the classification decision that changes your freight cost by 30–50%, and it is decided by how the battery ships, not by what the battery is.
| UN number | Proper shipping name | When it applies |
|---|---|---|
| UN3480 | Lithium ion batteries | Cells or packs shipped on their own, not installed in equipment |
| UN3481 | Lithium ion batteries contained in equipment | Packs installed inside the device they power |
| UN3481 | Lithium ion batteries packed with equipment | Pack and device in the same box, not assembled |
A 215 kWh cabinet shipped with its PCS installed may still be UN3480, because the battery is the article being transported and the cabinet is its enclosure. Whether it can be reclassified depends on the packaging and on the carrier’s dangerous goods desk — not on the supplier’s preference. Get the classification confirmed in writing before you book freight, because changing it after booking means re-booking.
4. Certificate of Origin — and Why the Type Matters
There is more than one kind, and using the wrong one costs you the tariff preference you were counting on.
- Non-preferential CO: states where the goods were made. Used for quota and for markets with no trade agreement. Easy to obtain.
- Preferential CO (Form A, Form E, EUR.1, etc.): claims a reduced or zero tariff under a specific trade agreement. Requires the goods to meet rules of origin — which for a battery pack usually means the cells must also originate in the same bloc, not just be assembled there.
- The trap: assembling imported cells into a pack does not usually confer origin. If your CO claims preferential origin but the cells came from elsewhere, the importer faces duty recovery plus penalties, years later.
If you are exporting from China to a country with a trade agreement, confirm with your freight forwarder which form applies and whether the specific HS code qualifies. Do not assume assembly equals origin.
5. The Dangerous Goods Declaration
Prepared by the shipper, signed by a trained person, and it must match the MSDS, the UN38.3 summary and the packing list exactly. Any inconsistency between these four documents is grounds for the carrier to refuse the booking or for customs to hold the container.
For sea freight this is the DG declaration under the IMDG Code. For air it is the Shipper’s Declaration for Dangerous Goods under IATA DGR. They are different documents with different formats — an air declaration will not be accepted for a sea shipment.
Customs does not read your invoice first. It reads the DG declaration, then checks whether the other four documents agree with it.
The Document Set, in Order
| # | Document | Who issues it | Lead time |
|---|---|---|---|
| 1 | UN38.3 test summary | Accredited third-party lab | Exists already, or 4–8 weeks to test |
| 2 | MSDS / SDS (16 sections) | Manufacturer, or a qualified SDS author | 1–3 days if the design is stable |
| 3 | DG declaration (IMDG or IATA) | Shipper, signed by trained personnel | Same day, once the rest is in order |
| 4 | Certificate of origin | Chamber of commerce or authorised body | 2–5 working days |
| 5 | Commercial invoice + packing list | Exporter | Same day |
The reason shipments get stuck is almost never a missing document in the abstract. It is a document that exists but disagrees with the others. Build the set once, keep it in one folder per model, and check the four cross-references — model number, UN number, Wh per unit, and net weight — every time you ship.
Clearing customs puts the container on site. Energising it is a different gate with a different document set — the connection package is covered in the EU grid connection guide.
Frequently Asked Questions
Does a battery cabinet need UN38.3 or just the cells inside it?
The pack needs its own UN38.3 test summary. Cell-level reports do not cover a finished pack, because the pack adds a BMS, a housing and new failure modes. If a supplier offers only cell reports for a cabinet shipment, that is a documentation gap you will discover at the port.
Can lithium batteries be shipped by air?
Yes, but under strict limits. UN3480 packs above 100 Wh generally cannot go as cargo on passenger aircraft, and state-of-charge must be at or below 30%. Most container-scale shipments go by sea, where the IMDG Code applies and the 30% SOC rule still applies to UN3480.
What state of charge should a battery ship at?
30% or below for UN3480. This is a regulatory requirement under both IATA and IMDG, not a manufacturer preference. Shipping at a higher SOC is a common cause of a carrier refusing a container at the gate.
How long does customs clearance usually take for a battery container?
Three to ten working days in most markets when the documents are consistent. Where they are not, it can run to weeks, and storage charges accrue daily. The document set is cheaper to fix before shipment than after.
Request the Document Pack
We can send a complete, model-specific document set — UN38.3 summary, 16-section MSDS, DG declaration template and CO guidance — for any cabinet or container in our range before you place an order.
For the full document set and the questions to ask before booking freight, see the transport document set in our downloads section.