Your product's passport for shipping

UN 38.3 is the transport safety test series every lithium cell and every lithium battery pack must pass before it can legally move by road, sea, or air. Most founders discover it at the worst possible moment — the first production shipment is packed and the freight forwarder asks for a document nobody prepared. It is not a performance test and not a quality standard. It checks exactly one thing: that the battery will not ignite or rupture under transport conditions. Without the paperwork, your product does not move.

What the requirement applies to

It applies to the battery, not the product — and separately to each cell model and each pack assembly. This distinction catches people out constantly: if you buy cells from a manufacturer who has already tested them, their report covers the cell. The pack you build from those cells is a new article that must be tested in its own right.

Three shipping configurations are treated differently, each with its own UN number, packing instructions, and marking rules:

  • Batteries shipped on their own (UN3480 for lithium-ion, UN3090 for lithium metal).
  • Batteries packed with the equipment.
  • Batteries installed inside the equipment (UN3481, UN3091).

The engineering side of the pack itself — cell selection, protection circuitry, and the battery management system — is covered in our article on battery pack design for a product. Design decisions there directly determine how easily you pass here.

What the test series includes

  • Altitude simulation (T1) — low pressure, simulating an unpressurized cargo hold.
  • Thermal cycling (T2) — repeated swings between extreme hot and cold.
  • Vibration (T3) and shock (T4) — real transport conditions across all modes.
  • External short circuit (T5) — terminals shorted at elevated temperature.
  • Impact or crush (T6) — mechanical abuse, method depending on cell format.
  • Overcharge (T7) — applies to rechargeable batteries.
  • Forced discharge (T8) — applies to cells.

Testing happens at an accredited lab, consumes a non-trivial number of samples — some fresh, some after a specified number of charge cycles — and typically takes several weeks. Put it in the schedule before your first production shipment, not after.

What it costs

For a single simple pack, expect a figure in the low-to-mid four digits USD. With multiple pack configurations, several cell suppliers, or a complex assembly, it climbs into five figures. The practical implication: minimize the number of battery variants in your product line early. Each variant is a separately tested article with its own report and its own budget line — a strong reason to consolidate before you commit, in the same spirit as the tradeoffs in value engineering.

The documents you will actually be asked for

  • UN 38.3 test summary. The central document. Current rules require it to be made available on request to any party in the transport chain, and it must explicitly identify the cell and pack models it covers.
  • Safety data sheet (SDS). Almost always demanded by forwarders and airlines even where not strictly mandated.
  • Correct UN number and proper shipping name, matching how the battery is actually packed relative to the equipment.
  • Packaging, marking, and labeling — the applicable packing instruction, the lithium battery mark or Class 9 hazard label, and in many cases a shipper's declaration for dangerous goods.
  • Trained shipping personnel. US hazardous materials rules require that whoever prepares the shipment has documented dangerous-goods training. In practice most startups satisfy this by using a qualified forwarder.

Air shipping limits worth knowing up front

Air is the strictest mode. Lithium-ion batteries shipped by themselves are limited to a partial state of charge — commonly around 30 percent of rated capacity — and in many cases are permitted on cargo aircraft only, not passenger aircraft. There are also caps on watt-hours per package and per consignment. The practical consequence is that ocean freight is sometimes not merely cheaper but operationally simpler for battery products; our comparison of ocean vs air freight lays out the tradeoff, and this is one more reason to plan around the Chinese New Year shipping crunch rather than into it.

When you have to test again

This is the part that surprises founders most: the certification is tied to a specific design. Any of the following may require retesting:

  • Changing the cell manufacturer — even for a nominally identical cell.
  • Changing capacity, voltage, or cell chemistry.
  • Changing the pack's mechanical construction, casing, or interconnection method.
  • Switching to an alternate supplier or a different factory for the same cell part number.

Locking your cell supplier and part number is therefore a regulatory decision, not just a purchasing one — the kind of long-term availability thinking that belongs in your bill of materials from the start, and that should be governed by a formal engineering change order process.

It is not the same as product certification

Passing UN 38.3 lets you transport the battery. It does not let you sell the product. Market access is a separate track — FCC certification for the radio, applicable safety standards such as the UL battery and product standards, and the broader product safety testing requirements for your category. Consumer products with rechargeable packs also draw CPSC attention, and children's products bring their own regime. Budget both tracks.

Projects House is an engineering firm, not a regulatory consultancy or law firm. This article is educational only. Transport rules for lithium batteries change and vary by mode and carrier — confirm current requirements with an accredited test lab, your carrier, and a qualified dangerous-goods advisor for your specific product. More related material is in our electronics development hub.

Plan the battery compliance path with the design

Projects House designs battery-powered products with the transport and safety testing path scoped from the start — cell selection, pack architecture, variant count, sample planning, and lab scheduling, so the certification is finished before the first container is booked. If your product contains a lithium battery of any kind, tell us about it through our contact form and we will map the testing you will need.