UN 38.3

What it is (precise)

"UN 38.3" names a subsection rather than a standalone standard: subsection 38.3 of Part III of the UN Manual of Tests and Criteria, the UN publication that carries the test procedures behind the UN Model Regulations on the transport of dangerous goods. The current text is the eighth revised edition, Rev.8 (2023), plus Amendment 1 (2025) — adopted by the UN TDG Committee in December 2024 and, per UNECE, amending subsection 38.3 itself, including the definition of rupture — so a careful citation reads "Manual of Tests and Criteria, Rev.8, Amend.1, Part III, subsection 38.3".

In Rev.8 the subsection is titled "Lithium metal, lithium ion and sodium ion batteries", and its stated job is classification: it presents the procedures for classifying such cells and batteries under UN numbers 3090, 3091, 3480, 3481, 3551 and 3552 of the Model Regulations. Keep the two documents apart when citing — the Manual and the Model Regulations are separate publications on separate revision cycles, and quoting an edition number from one against the other is a standing source of citation errors.

The test set is eight type tests. T.1, altitude simulation, stores the samples at 11.6 kPa or less for at least six hours at ambient temperature — air transport at low pressure. T.2, thermal test, cycles them between 72 °C and −40 °C for ten cycles, at least six hours per extreme (the Manual recommends at least twelve for large cells and batteries) with at most 30 minutes between extremes — probing seal integrity and internal connections under rapid temperature swings. T.3 simulates vibration during transport and T.4 assesses robustness against cumulative shocks.

T.5 is an external short circuit, T.6 impact/crush — mechanical abuse that may produce an internal short — T.7 evaluates a rechargeable battery's ability to withstand overcharge, and T.8 a cell's ability to withstand forced discharge. T.6 hides two procedures in one slot: per the Rev.8 text, impact applies to cylindrical cells of 18 mm diameter and up, crush to prismatic, pouch, coin and smaller cylindrical cells — which puts every large prismatic LFP storage cell on the crush procedure.

Applicability splits between cells and batteries. All lithium cell types take T.1 through T.6 plus T.8; non-rechargeable (primary) battery types take T.1 through T.5; rechargeable battery types take T.1 through T.5 plus T.7; and rechargeable single-cell batteries with overcharge protection take T.7 as well. So T.6 and T.8 are cell-level tests a battery never sees, and T.7 is a rechargeable-battery test. The Rev.8 text gives sodium-ion its own pattern: sodium-ion cells take T.1 through T.6 with no T.8, and rechargeable sodium-ion batteries take T.1 through T.5 plus T.7.

Why it matters in a real grid-scale project

For a project team the operative deliverable is the Test Summary of paragraph 38.3.5.

Manufacturers and subsequent distributors of cells or batteries manufactured after 30 June 2003 must make it available — the obligation sits in the Model Regulations at 2.9.4(g), with an exception only for button cells installed in equipment — and its required content includes the manufacturer's and test laboratory's identification, the test report number and date, a description of the cell or battery, the list of tests conducted with pass/fail results, and the edition of the Manual the type was tested against.

PHMSA puts the effective date at 1 January 2020 under the ICAO Technical Instructions and the IMDG Code, and 1 January 2022 in the US hazmat regulations, where 49 CFR 173.185 applies the duty to cells and batteries manufactured on or after 1 January 2008 — two regimes, two manufacture-date cutoffs, and a document request should quote the right one.

Which entry the hardware travels under depends on how it is packed. Batteries shipped on their own are UN 3480, lithium ion batteries, Class 9; UN 3481 is a single UN number carrying two distinct proper shipping names — lithium ion batteries contained in equipment, and lithium ion batteries packed with equipment.

A complete containerized BESS is different again: the Model Regulations assign lithium batteries installed in a cargo transport unit and designed to provide power external to it to UN 3536, under special provision 389 — the batteries inside are exempt from package marking and labelling, the container itself displays the UN number and is placarded on two opposing sides, and every cell and battery inside must still be of a type that passed the 38.3 tests.

At sea, the mandatory regime under SOLAS is the IMDG Code, currently the 2024 Edition incorporating Amendment 42-24, mandatory since 1 January 2026. At end of life the same machinery runs in reverse — removed modules and racks re-enter the dangerous-goods system as UN 3480, which is why serious decommissioning estimates carry dangerous-goods packaging and transport as real line items.

Typical values and standards

UN 38.3 sits at the bottom of a stack of transport law. The Manual supplies the tests, the UN Model Regulations turn the results into classification, and the modal codes make it enforceable — the ICAO Technical Instructions and IATA Dangerous Goods Regulations in the air, the IMDG Code at sea, ADR and RID for European road and rail, 49 CFR in the US.

The famous 30 percent state-of-charge ceiling lives in that top layer, in the air rules alone: ICAO TI / IATA packing instruction 965 requires lithium-ion batteries shipped by themselves by air to be at a state of charge no greater than 30 percent of rated capacity — mirrored in the US by special provision A100 in 49 CFR 172.102 — with anything higher needing approval from both the State of Origin and the State of the Operator, and UN 3480 barred from passenger aircraft without approval.

UN 38.3's entire contribution to that rule is paragraph 38.3.2.3, the methodology for determining rated capacity. IATA's guidance shows the limit widening from 1 January 2026 to packed-with-equipment shipments under packing instruction 966, while for batteries contained in equipment 30 percent remains a recommendation.

The companion standards draw the other boundary. UN 38.3 qualifies a battery for the journey; safety in installed service belongs to UL 1973 (ANSI/CAN/UL 1973:2022, batteries for stationary and motive auxiliary power applications, cell through rack) in North America and IEC 62619:2022 (secondary lithium cells and batteries for industrial applications) internationally, with UL 9540 listing the complete energy storage system and UL 9540A — a test method, never a certification — characterizing fire propagation.

A cell datasheet's certification line typically reads IEC 62619, UL 1973, UN 38.3 and a UL 9540A report in one breath, but the string spans transport law, product safety and fire characterization, and no entry substitutes for another.

How it shows up in specs, studies and contracts

In procurement the Test Summary is the checkable artifact. Ask for it alongside the UL 1973 and IEC 62619 certificates and verify three fields: that the cell or battery description matches the exact model and revision being delivered, that the tests listed follow the applicability pattern for the article in question — a battery-level summary claiming T.6 or T.8 was run on the battery misreads the standard, since those are cell tests — and that the summary names the edition of the Manual the type was tested against, as 38.3.5 requires it to.

Because the duty extends to subsequent distributors, an integrator reselling cells inside modules owes the summary too; a supplier who cannot produce one within days is a warning sign that runs well beyond paperwork.

In the transport chapter of a supply agreement, the entries decide the mechanics: which UN number each delivery moves under, who prepares the dangerous-goods documentation, and at what state of charge modules are dispatched — commonly about 30 percent or lower for lithium modules, a practice the air rules turn into a hard ceiling for anything flown.

For a delivered containerized system, UN 3536 under special provision 389 is the arrangement to look for, and the ocean leg falls under the IMDG Code. For spare modules arriving by air years later, packing instruction 965 or 966 and their state-of-charge limits govern, so a warranty-replacement clause that promises fast air freight has promised a 30-percent-SoC shipment as well — worth writing down while everyone still agrees on it.

Common pitfalls

The classic error is crediting UN 38.3 with the 30 percent state-of-charge rule — that rule belongs to the air-mode codes, and repeating the misattribution in a specification produces requirements no test lab can certify against.

A close second is reading "UN 38.3" on a datasheet as a safety credential: passing eight transport tests says nothing about how the product behaves in twenty years of installed service, which is UL 1973 and IEC 62619 territory, nor about fire propagation at rack scale, which is what a UL 9540A report characterizes. Watch the two manufacture-date cutoffs as well — after 30 June 2003 in the UN Model Regulations, on or after 1 January 2008 in the US 49 CFR — and keep them out of the same sentence.

Citation traps round out the list. Older sources describe 38.3 as a lithium-only subsection; Rev.8 retitled it to cover sodium-ion cells and batteries, with a slightly different test pattern. UN 3481 is one UN number with two proper shipping names, and the declaration must carry the right one — contained in equipment and packed with equipment are different packing situations.

And because Amendment 1 (2025) changed subsection 38.3 itself, including the rupture definition, pass/fail wording quoted from pre-amendment copies may no longer match the current text — cite the edition and amendment, not just the number.