UN 38.3 is the section of the United Nations Manual of Tests and Criteria that a lithium cell or battery must pass before it can be transported. It consists of eight tests covering altitude, thermal cycling, vibration, shock, external short circuit, impact and crush, overcharge and forced discharge. Passing it makes a battery legal to move, not safe to use. The document carriers and customers actually ask for is the test summary, not the full test report.
The distinction that matters first
UN 38.3 is a transport requirement. It exists so that a lithium battery can be carried by air, sea or road without becoming a hazard to the vehicle and the people in it.
It is not a product safety standard. Passing it does not make a product safe for a consumer to use, and failing it does not necessarily mean the product is dangerous in normal operation. The two questions — can this be moved, and is this safe to use — are answered by different documents, and a supplier who conflates them has either misunderstood the requirement or is hoping you will.
The product safety counterpart is a battery safety standard, most commonly IEC 62133-2. In practice most serious suppliers hold both, and both are requested together during supplier qualification.
The eight tests
The regime consists of eight tests, conventionally referred to as T1 to T8. Each simulates a condition a battery could encounter in transport or handling.
| Test | Simulates |
|---|---|
| T1 | Altitude simulation — the reduced pressure of an aircraft hold or an unpressurised cargo area |
| T2 | Thermal test — cycling between high and low temperature extremes |
| T3 | Vibration — the mechanical vibration of transport |
| T4 | Shock — impacts during handling and loading |
| T5 | External short circuit — a short across the terminals, at elevated temperature |
| T6 | Impact and crush — mechanical deformation of the cell |
| T7 | Overcharge — charging beyond the specified limit |
| T8 | Forced discharge — forced discharge of a cell |
A battery must pass all eight. The results are recorded by the testing laboratory, and the manufacturer is required to make a summary of them available.
Report versus summary
This is the practical crux, and it is where suppliers most often come unstuck.
The test report is the laboratory's full record: test conditions, measurements, pass and fail results, equipment used. It is long, technical, and usually confidential.
The test summary is a shorter document in a standardised format. It states what was tested, which tests were performed, and that the results met the criteria. It does not contain the laboratory's raw data.
In day-to-day commercial practice, it is the test summary that gets requested — by carriers, by freight forwarders, by downstream customers and by marketplaces. A supplier who can produce a current test summary within a day is a supplier who has their documentation in order. A supplier who cannot, or who offers a certificate instead, has told you something worth knowing before you place an order.
What applies to what
The rules are not a single threshold. They depend on the watt-hour rating of the battery, on whether it is shipped alone, packed with equipment or installed in equipment, and on the mode of transport. Air freight is the most restrictive and is where most of the practical constraints come from.
Two consequences follow for a product team:
The watt-hour rating is a design decision, not just a specification. A product sitting just above a threshold faces a different set of packing, labelling and documentation requirements from one just below it. If a design change can move a product across a threshold without harming its commercial case, that is worth knowing before the tooling is cut.
The documentation burden is per configuration. A battery shipped on its own and the same battery installed in a finished product are treated differently. A single product line can generate several documentation requirements.
Four things that are commonly misunderstood
"Our cells are certified, so we are covered." The cells may have been tested as cells. The battery as assembled is a different article with different construction, and it requires its own assessment. A cell test does not cover a pack.
"We do not ship batteries on their own." A battery inside a product is still a lithium battery being transported. The requirements differ by configuration; they do not disappear.
"It is a formality." It is a legal requirement with consequences at the point of shipping. A consignment without valid documentation can be refused, delayed, returned or destroyed, and the cost and liability sit with the shipper rather than the carrier.
"The test was done once, so it is done." Test summaries carry an issue date and reference a specific product. A summary issued for a different product, or for an earlier version of the same product, does not cover what is being shipped now.
What to ask a supplier
Four questions, in order, and the answers are quick to verify:
- Which cells are used, and what is their watt-hour rating?
- Is there a current UN 38.3 test summary for the battery as assembled, not for the cells?
- Can you send it today?
- Which configuration does it cover — battery alone, packed with equipment, or installed?
A supplier who answers all four without hesitation is operating competently. One who answers the first two and deflects the rest is telling you where their documentation stops, which is useful to know before the goods are on a pallet rather than after.