The Three Standards Are Not Layers — They Are Different Stops on the Same Shipment

UN38.3, IEC 62133, and UL 1642 look like three rows of the same test report on a certificate stack. They are not. Each one covers a different part of the cell’s lifecycle, and each one is asked for by a different party at a different point in the shipment chain.

UN38.3 is the transport test. It is defined in the United Nations Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, and it covers the conditions that a lithium cell experiences during transport — altitude pressure differential, thermal cycling, vibration, shock, external short circuit, impact, overcharge, and forced discharge. The test summary is what the carrier checks at acceptance, before the shipment is loaded onto a vessel or an aircraft.

IEC 62133 is the cell safety standard. The relevant edition for lithium cells is IEC 62133-2:2017, which covers portable lithium-ion cells for portable applications. The standard covers the cell’s safety design under abuse conditions — overcharge, forced discharge, external short, thermal abuse, crushing, and low-pressure simulation. The test report is what the cell’s downstream customer checks when integrating the cell into a finished product, and what the safety case for the end product references.

UL 1642 is the cell safety standard published by UL Solutions for the North American market. It covers single-cell and multi-cell lithium batteries, with the test conditions aligned to the US market’s safety expectations. For finished products, the relevant UL standard is UL 2054 for information technology equipment or UL 2271 for light electric vehicle applications, but the cell safety side still references UL 1642 for the cell.

The three certifications stack on the same cell, but each one is asked for by a different party. The carrier asks for UN38.3. The end-product safety case asks for IEC 62133 or UL 1642. The destination market’s regulations reference the same cell safety standard under its own document number. The reference for the international cell safety framework baseline is the IEC 62133-1:2017 standard for portable batteries (nickel systems) and the related UL standards resources page.

UN38.3 — The Transport Certificate Every Shipment Crosses

UN38.3 is the transport test required for the international shipment of lithium cells and batteries. The test is defined in the United Nations Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, and the test summary is the document the carrier references at acceptance. The test applies to all lithium chemistries — lithium-ion, lithium polymer, lithium iron phosphate, and lithium primary — and to standalone cells, cells packed with equipment, and cells contained in equipment.

The UN38.3 test sequence is eight tests, designated T1 through T8. T1 is altitude simulation, which checks the cell’s response to the low-pressure condition at typical aircraft cargo altitudes. T2 is thermal cycling, which checks the cell’s response to rapid temperature transitions between -40°C and +75°C. T3 is vibration, which checks the cell’s response to the vibration profile of road, sea, and air transport. T4 is shock, which checks the cell’s response to the mechanical shock of handling and stacking. T5 is external short circuit, which checks the cell’s response to a direct short across the terminals at the cell’s terminal voltage. T6 is impact, which checks the cell’s response to a mechanical impact on the cell case. T7 is overcharge, which checks the cell’s response to charging at a higher voltage than the cell’s rated maximum. T8 is forced discharge, which checks the cell’s response to a forced discharge to below the cell’s rated minimum voltage.

For a Zscells lithium-ion cell, the UN38.3 test summary is the first document the carrier reviews at acceptance. The test summary is per cell model, not per batch, and it remains valid for the same cell design across production runs unless the cell design changes in a way that requires re-testing. The reference for the transport-side rules that the test summary supports is the IATA Dangerous Goods Regulations for air transport, the FAA Hazmat regulations for US air transport, and the Portable Rechargeable Battery Association for industry guidance on the application of the test conditions to specific cell chemistries.

IEC 62133 — The Safety Standard for the Cell Itself

IEC 62133 is the cell safety standard published by the International Electrotechnical Commission. The 2017 edition split the standard into two parts: IEC 62133-1 for nickel systems and IEC 62133-2 for lithium systems. For lithium-ion cells, the relevant edition is IEC 62133-2:2017, which covers portable lithium-ion cells for portable applications.

The IEC 62133-2 test program covers the cell’s safety design under abuse conditions. The tests include overcharge, forced discharge, external short circuit, thermal abuse, crushing, low-pressure simulation, and mechanical shock. The test report is the document the cell’s downstream customer references when integrating the cell into a finished product, and the document the end product’s safety case references for the cell-side safety data.

IEC 62133-2 is the cell safety standard recognized across most non-US markets. CE-marked end products sold in the European Union reference IEC 62133-2 for the cell safety data. End products sold in Japan, Korea, Australia, and most of Southeast Asia also reference IEC 62133-2. The United States and Canada are the exceptions — the cell safety standard for these markets is UL 1642, not IEC 62133-2.

The right application of IEC 62133-2 is as a cell-level safety case. The cell’s downstream customer integrates the cell into a finished product, and the finished product’s safety case references the IEC 62133-2 test report for the cell. The carrier, by contrast, references the UN38.3 test summary for the cell, not the IEC 62133-2 test report. The two documents stack on the same cell, but at different points in the shipment chain.

The reference for the IEC 62133 framework is the IEC 62133-1:2017 standard for the nickel portion and the IEC 62133-2:2017 standard for the lithium portion. The related industrial lithium cell safety standard is the IEC 62619:2022 standard for secondary lithium cells for industrial applications, which covers lithium cells used in stationary applications, energy storage, and light electric vehicles.

UL 1642 — The North American Cell Safety Standard

UL 1642 is the cell safety standard published by UL Solutions for the North American market. The standard covers single-cell and multi-cell lithium batteries, with the test conditions aligned to the US and Canadian safety expectations. The standard’s scope is the cell safety design, not the finished product — the finished product carries its own UL standard, with UL 2054 for information technology equipment and UL 2271 for light electric vehicle applications as the two most common end-product standards.

The UL 1642 test program covers the cell’s response to a set of defined abuse conditions. The tests include short circuit, overcharge, overdischarge, thermal abuse, mechanical shock, vibration, drop, and impact. The test report is the document the cell’s downstream customer references when integrating the cell into a finished product for the North American market, and the document the end product’s safety case references for the cell-side safety data.

For a Zscells 18650 lithium-ion battery shipped to a North American customer, the UL 1642 test report is the cell safety data the customer references. The cell is also subject to the UN38.3 transport test for the international shipment, and the cross-shipment stack is UN38.3 plus UL 1642 plus the relevant end-product UL standard. For the same cell shipped to a European Union customer, the cross-shipment stack is UN38.3 plus IEC 62133-2 plus the relevant CE-marked end-product standard.

The right application of UL 1642 is as a cell-level safety case for the North American market. The end product’s safety case references the UL 1642 test report for the cell. The carrier, by contrast, references the UN38.3 test summary for the cell, not the UL 1642 test report. The two documents stack on the same cell, but at different points in the shipment chain.

The reference for the UL 1642 framework is the UL battery safety certification solutions page, which links to the relevant UL standards for cells and end products. The UL ecosystem that supports the cell safety framework is the UL standards resources page, which lists the relevant UL standards for the application of cell safety to finished products.

The 8-Dimension Selection Matrix — Which Certificate for Which Market

The three certifications stack on the same cell, but each one is asked for by a different party at a different point in the shipment chain. The matrix below is the decision matrix for which certificate is required for which market and which shipment mode.

The matrix shows that the three certifications are not interchangeable. A cell that has UNE 62133-2 documentation but no UN38.3 test summary will be rejected at the carrier acceptance check. A cell that has UL 1642 documentation but no IEC 62133-2 documentation will be referenced in the EU end-product safety case as an exception, not as the default. The right approach is to plan the certification stack up front, identify the destination market, identify the shipment mode, and plan the test program to cover all three documents.

The reference for the underlying standards framework is the IEC 62133-2:2017 standard for the cell safety side and the UL standards resources page for the cell safety side under the UL framework. The cross-shipment discussion is what the engineering team uses when the same cell goes to multiple destinations, which is the common case for a lithium-ion battery sold into the consumer electronics, e-mobility, and industrial markets.

The Transport Stack — Air / Sea / Road and the Document Trail

The transport acceptance check is the point at which the carrier confirms the shipment is covered by the UN38.3 test summary. The check applies to all three transport modes — air, sea, and road — and the documents the carrier references are the same across the three modes. The differences are in the supplementary documentation that the carrier requires for each mode.

For air transport, the carrier references the IATA Dangerous Goods Regulations. The document trail is the UN38.3 test summary plus the Shipper’s Declaration for Dangerous Goods (DGD), which is mandatory for lithium batteries shipped as Class 9 dangerous goods on air transport. The carrier acceptance check verifies that the UN38.3 test summary is on file and that the DGD matches the cell description on the test summary.

For sea transport, the carrier references the International Maritime Dangerous Goods Code (IMDG Code). The document trail is the UN38.3 test summary plus the multimodal dangerous goods form, which is the International Maritime Organization’s equivalent of the IATA DGD. The carrier acceptance check verifies the UN38.3 test summary and the multimodal form.

For road transport, the carrier references the relevant regional agreement — ADR for European road transport, or the national hazmat regulations for cross-border road transport in other regions. The document trail is the UN38.3 test summary plus the relevant transport document, which is typically the consignment note with the dangerous goods declaration.

The reference for the air transport rules is the IATA Dangerous Goods Regulations, which is the industry standard for the air transport of lithium batteries. The reference for the US air transport rules is the FAA Hazmat regulations, which layer on top of the IATA framework for US-origin shipments. The reference for the industry-side guidance is the Portable Rechargeable Battery Association, which publishes specific guidance on the application of the transport rules to lithium chemistries.

The Engineering Support Conversation We Have with Battery Importers

When a battery importer or an OEM integrating lithium cells into a finished product sends Zscells a request for certification guidance, the conversation usually goes one of three ways. The first is that the importer has a defined destination market and a defined shipment mode, and is asking Zscells to confirm the certification stack that the cell already carries. The second is that the importer is launching a new product and is asking Zscells to plan the certification stack for the target market and shipment mode. The third is that the importer is troubleshooting a transport rejection or a customer safety case and needs to reconcile the cell’s documentation against the carrier’s or the customer’s requirements.

In the second and third cases, the practical value is in the cell’s existing certification stack and the cell’s internal test data. The cell’s certification stack carries the UN38.3 test summary, the IEC 62133-2 test report, and the UL 1642 test report where applicable. The cell’s internal test data carries the cell’s actual measured performance against the abuse conditions. The cross-reference of the two is what allows the importer to identify the documentation gap and to plan the test program that closes the gap.

For importers who want to open a Zscells certification consultation request on a new market or a transport rejection, the right entry point is the contact page with the cell model, the destination market, the shipment mode, and a description of the specific question or documentation gap. The Zscells engineering team can return a certification stack review or a transport stack interpretation within a few working days for projects at the standard three-certification combination.

One final note. This article covers the three-certification stack as the conservative structure for a lithium battery shipment crossing international borders. For projects where the cell is for a single, well-defined market with a single shipment mode, a two-certification stack may be defensible. The right conversation is the same — destination market, transport mode, cell certification stack — applied to the specific project. If the project sits at the edge of those conditions, the certification discussion is worth having before the test program is locked.

FAQ — UN38.3 vs IEC 62133 vs UL 1642