One Battery Can Freeze Your Entire Shipment
China Lithium Battery Product Import Guide — UN38.3 Certification to Air/Sea Shipping Restrictions

Hello, this is GreenFrog Seoul.

"I ordered 500 power banks and the courier bounced them — said they can't send them."
"The factory says air freight takes 3 days, so why are we being told ours can only go by sea?"
"I asked for the UN38.3 report and the factory asked back, 'What's that?'"

Wireless earbuds, power banks, power tools, e-scooter batteries — anything with a lithium battery inside looks like ordinary consumer goods. But the moment that item crosses a border, it's treated as dangerous goods. Lithium batteries can overheat and ignite under impact, overcharge, or short circuit, so carriers demand extra rules and paperwork before they'll load them onto an aircraft or a vessel. Place an order without knowing this, and you end up with finished goods that can't go on a plane or a ship.

Shipping a lithium battery product isn't "just drop it with a courier." A passed UN38.3 test, an MSDS on hand, dangerous-goods packing and marking, and mode-by-mode transport limits all have to line up before the goods move. Drawing on the rejection and detention cases we've handled, GreenFrog Seoul lays out the must-check points for importing lithium battery products from China — in a single page.

This guide covers: what UN38.3 is and why you need it, how air freight splits battery-only, contained-in-equipment, and packed-with-equipment, the conditions for sea freight (IMDG), a required-document checklist, how to pick a forwarder or courier that handles dangerous goods, Korean customs points like KC certification, and the mistakes sellers make most often.

1. UN38.3 — The Starting Point of Lithium Battery Shipping

Before a lithium battery can be carried anywhere, you first have to prove it is "safe to transport." The international benchmark for that proof is UN38.3 — section 38.3 of the UN Manual of Tests and Criteria, which sets out eight tests that lithium cells and battery packs must pass.

Factories rarely make their own cells; most buy them from cell makers like ATL, BAK, or Lishen. So the UN38.3 report is usually held by the cell or battery-pack maker, not the finished-product factory. Before ordering, ask for "the UN38.3 test report for this battery," and check that the model name and ratings (capacity, voltage) on the report match the battery actually going into your product.

2. MSDS — Battery Composition and Hazard Data

An MSDS (Material Safety Data Sheet) sets out the chemicals in a product, its hazards, and how to handle it and respond in an emergency. For cargo where composition can be a problem — lithium batteries, cosmetics, liquids, powders — forwarders and airlines ask for the MSDS. For batteries, you get the MSDS issued by the cell maker from your factory and hand it to the forwarder.

The MSDS itself isn't a mandatory customs document, but the forwarder or courier checks it at the point of accepting the dangerous-goods shipment. Without an MSDS, the dangerous-goods declaration can't even proceed, and the shipment stalls. If UN38.3 proves "is this battery fit for transport," the MSDS is the document that says "what's inside and how to respond if something goes wrong."

3. Air Freight — Always Distinguish Battery-Only, Contained, and Packed-With

This is the most confusing and the most failure-prone part of shipping lithium battery products. The same battery ships under completely different rules depending on how it's packed with the product. IATA's Dangerous Goods Regulations (DGR) split it into three cases.

It splits again by capacity (Wh)

Regulation intensity is graded by watt-hours (Wh) for lithium-ion and by lithium content (g) for lithium-metal. Small capacities get the relaxed provisions (Section II); above the thresholds, the battery becomes fully regulated.

• Li-ion cells ≤ 20Wh / packs ≤ 100Wh: most power banks, earbuds, and small devices fall here. Relaxed provisions may apply, but you still have to follow dangerous-goods marking and packing rules
• Packs over 100Wh: e-scooter and e-bike batteries, high-capacity power banks. Fully regulated, so a dangerous-goods declaration, dedicated packaging, and a qualified forwarder are mandatory
• Over 160Wh: air freight is essentially off the table, and these often have to move by sea

4. Sea Freight — IMDG Class 9

When air is blocked or volumes are large, sea freight is the answer. Lithium batteries are dangerous goods at sea too, classified as Class 9 (miscellaneous dangerous goods) under the International Maritime Dangerous Goods (IMDG) Code. The UN numbers are the same as for air: UN3480/3481 (Li-ion), UN3090/3091 (Li-metal).

Sea is more forgiving on capacity limits and cheaper on freight. Cargo that's essentially impossible by air, like scooter and e-bike batteries over 100Wh, can go by sea. You do have to observe the following.

• Dangerous-goods packing and marking: apply the Class 9 lithium battery mark and label to the box and use UN-spec packaging
• Dangerous Goods Declaration (DGD): submitted to the carrier before loading, backed by the MSDS and the UN38.3 summary
• LCL constraints: many carriers and consolidators won't accept dangerous goods in mixed small-lot (LCL) shipments. A full container (FCL) is often smoother

5. Required Documents & Verification Checklist

Lithium battery products need dangerous-goods materials on top of ordinary cargo documents before a shipment will be accepted. Below is what to request from your factory and cell maker at the order stage.

6. Choosing a Forwarder / Courier — First Confirm They Handle Dangerous Goods

Not every forwarder handles dangerous goods. Lithium batteries can only be accepted by companies that hold dangerous-goods qualifications (an IATA DGR–certified handler) and have secured airline dangerous-goods space. It helps to split your approach: ordinary courier for small lots, forwarder for bulk and containers.

Checkpoints when choosing

• Dangerous-goods experience: ask first, "do you regularly ship lithium batteries as dangerous goods?" Inexperienced companies often accept and then bounce the shipment
• Understands contained/packed-with/only: a forwarder who nails the UN number and PI (packing instruction) in the quote is one you can trust
• State-of-charge guidance: if they proactively mention the 30%-or-below charge requirement for standalone batteries, they know the work
• DG surcharge stated: dangerous goods carry a DG surcharge on top of ordinary freight. Confirm the quote includes this line item

7. Korean Customs — Domestic Rules like KC Certification

Clearing transport and arriving at the port or airport isn't the finish line. Most products with a lithium battery inside are subject to domestic safety certification (KC). Clearance itself proceeds separately from dangerous-goods transport, but to sell, you have to meet the item-by-item KC requirements.

8. Real Cases Where Shipments Get Stuck — and Common Mistakes

① Hunting for UN38.3 after everything is made

Requesting the report only after mass production wraps, then finding the factory's cell maker used cheap cells with no UN38.3. Now you have to remake the batteries or swap the cells, and the whole delivery slips. Nail down the battery spec and UN38.3 possession as a condition in the purchase order.

② Booking air by mAh alone, then getting bounced

Trying to air-ship a 20,000mAh power bank assuming it was a safe 74Wh, only for the parallel configuration to push it past 100Wh and block acceptance. Wh changes with cell configuration (series/parallel), so get the final Wh value from the factory and confirm it.

③ Booking a standalone battery on passenger space

Rushing a replacement battery pack (UN3480, battery-only) onto air freight, then waiting days for cargo-aircraft space because it's a passenger-forbidden item. Plan standalone batteries as CAO (cargo aircraft) or sea from the start.

④ Courier return for undeclared dangerous goods

Putting a battery-embedded device into a courier as ordinary cargo with no declaration, only for the lithium battery to be spotted during sorting and returned to origin. The return freight and time are a straight loss. Even for small lots, ship through a channel that files a dangerous-goods declaration.

⑤ Detention over missing labels or packaging

Detention at the airline or customs stage because the Class 9 lithium battery label and handling marks were missing. UN-spec packaging, labels, and documents move as a set. Confirm in advance whether packing and marking are within the forwarder's scope.

9. Pre-Order Checklist

Order / Contract Stage

• Confirmed the cell maker and model name and received the UN38.3 report/summary
• Calculated the battery's Wh (voltage × capacity) and decided the transport mode (air/sea)
• Obtained the MSDS from the cell maker
• Checked the item's KC certification requirements and started the process

Transport Design Stage

• Decided whether it's battery-only, contained, or packed-with, and confirmed the UN number and PI
• Selected a forwarder/courier that regularly handles dangerous goods
• Received a quote that includes the DG surcharge
• Worked backward from the deadline to schedule sea transit and customs

Shipping / Customs Stage

• Confirmed the Class 9 label/marks and UN-spec packaging were applied
• Handed the DGD and supporting documents (MSDS, UN38.3) to the forwarder
• Aligned the KC certification timeline with clearance and sale

Closing — Battery Shipping Is a Sourcing Decision

Most lithium battery mishaps come from the "make the goods first, think about shipping later" order. Even fully built, batteries with no way to ship just sit in the warehouse.

To sum up: confirm the cell maker, UN38.3, and MSDS before you order; calculate the Wh to decide up front whether air is possible or it has to go by sea. Because the UN number and packing instruction change with battery-only, contained, and packed-with, design the transport mode accordingly, then pick a dangerous-goods forwarder and get a quote that includes the DG surcharge. KC certification for domestic sale is separate from transport, so start it as you source. GreenFrog Seoul works alongside Korean importers through the whole process — from battery spec and UN38.3 checks to transport-mode design, dangerous-goods forwarder referrals, and KC procedure guidance. Whenever you hit a wall sourcing lithium battery products, reach out.