UN 38.3: what it is and why your battery cannot ship without it

T1 altitude simulation, T2 thermal test, T3 vibration, T4 shock and T5 external short circuit are conducted in sequence on the same samples. Together they simulate what transport does to a cell: low pressure, repeated temperature extremes, sustained vibration, mechanical shock and a short across the terminals.

T6 impact or crush applies to cells and to single-cell batteries, and simulates physical damage to the cell case.

T7 overcharge applies to rechargeable batteries and simulates a charger that does not stop.

T8 forced discharge applies to cells and simulates a cell being driven below zero volts by the others in a pack.

The order matters and so does the sequencing: applying T1–T5 to the same samples is deliberate, because a cell that survives each test individually can fail the accumulation. A report that shows tests run on fresh samples for each stage is describing something other than the standard.

The test report is the full record and is held by whoever paid for the testing — usually the cell maker for cells and the pack maker for packs. It is often treated as confidential, which is why the summary exists.

The test summary is a defined set of information: the manufacturer and contact, the description and identification of the cell or battery, the mass, the watt-hour rating or lithium content, a list of the tests conducted and their results, a reference to any assembled-battery testing requirements, the test report number, the date of the summary, and the name, title and signature of a person authorised to sign it. That last item is not a formality — an unsigned summary is a form somebody filled in.

THE DATE. Secondary sources say the test summary has been mandatory since 1 January 2020. The United States regulator's own guidance says the requirement was effective 1 January 2022 and was subsequently revised effective 10 May 2024. Both statements can be correct, because the UN Model Regulations and each national implementation run on their own timetables. So this page publishes no single date: assume the summary is required, and check the date that applies in the jurisdictions your shipment moves through.

What to check on the documents you are handed. The model or design named on the report against the model you are buying. The applicant against the company invoicing you. The watt-hour rating against the product's own marking. The laboratory, and whether the report is a genuine report rather than a photocopy of somebody else's. And whether the pack, not only the cell, has been tested — a tested cell inside an untested pack is not a tested battery.

It is a transport requirement, not a product-safety approval. Passing UN 38.3 says a design survived eight transport tests. It says nothing about whether the product may be placed on the market in the EU, the UK, the United States or anywhere else — those are separate regimes with separate documentation.

Without it, the shipment does not move. Carriers, freight forwarders and postal operators all require the documentation for lithium cells and batteries, and a shipment presented without it is refused, held or — if it was declared incorrectly — treated as an undeclared dangerous goods offence, which is a different order of problem for the shipper.

And "the goods are already in the warehouse" does not help. Retro-testing a design takes weeks in a queue at a laboratory, so a missing report is a schedule failure rather than a paperwork failure. Ask for it at quotation, not at booking.

A design change can invalidate it. A different cell supplier, a different cell model, a changed pack configuration or a changed capacity can all require retesting. This is the most common way a compliant product becomes a non-compliant one silently: the factory changes a cell in a cost-down and nobody re-runs the paperwork.

Which is why the cell specification belongs in your contract. Name the cell manufacturer and model, require notification of any change, and require that the change be accompanied by the updated documentation before production.

At quotation: the UN 38.3 test summary for the exact model, and confirmation of who holds the full report. Read the signature block.

Before the order: the cell manufacturer and model written into the specification, and a clause requiring notification and updated documentation if either changes.

Before shipment: the safety data sheet for the battery, the packing arrangement the freight forwarder requires, and the marking and labelling on the cartons. The packing instructions and the watt-hour thresholds are not on this page — the guides on watt-hour conversion and shipping lithium batteries by air carry them, and one set of numbers in one place is how they stay right.

And keep copies. When a carrier, a customs authority or a marketplace asks, the request has a deadline, and a document sitting in a supplier's inbox in another time zone is not a document you hold.

One more thing worth doing: check the summary against the physical product. The watt-hour rating on the summary should match the marking on the battery. When it does not, you have learned something before a carrier does.