Battery chemistries that are lithium-based must undergo UN38.3 testing requirements before being transported. This testing certifies that the batteries are safe and will not pose a safety risk during shipping over air, water, rail, or road transportation methods.
Lithium-based batteries are the only chemistries that undergo this testing requirement. The UN38.3 testing requirement is accepted as a national and international standard that all battery pack manufacturers must abide by when they plan to ship lithium batteries as individual cells, in packs, or when placed inside products.
Thermal Runaway and why Testing Is Necessary
Lithium-based batteries are manufactured with lithium or lithium-ion metal. These metals are highly reactive and unstable components that offer very high energy density. However, the batteries may experience thermal runaway. Thermal runaway occurs when a cell in the battery pack undergoes temperatures that are higher than the battery's melting point. The battery begins to build and/or vent hot gases that could create a chain reaction with the other battery cells in the pack. Once the batteries reach this stage, they may leak, rupture, explode, or catch fire.
Lithium batteries are designed with graphite materials as the cathodes that are near the lithium and lithium-ion metal oxide anodes. A passivation film layer known as Solid Electrolyte Interphase (SEI) is formed along the anode of the battery to slow down electrolyte decomposition during the first few charging cycles of the battery. Unfortunately, that SEI film can decompose due to high temperatures, which causes the lithium metal or lithium-ion metal to embed into the graphite material. A negative reaction occurs between the lithium metal-embedded graphite, the electrolyte, and the polyvinylidene fluoride (PVDF) binder to create an extremely large amount of uncontrollable heat in the battery.
Lithium battery packs packaged with proper shipping labels.
Due to this issue, lithium-based batteries are considered Class 9 hazardous and dangerous goods according to the United Nation regulatory organization. This regulatory body has created the UN38.3 testing as a globally recognized testing standard that will evaluate whether the design and manufacturing of lithium-based batteries meet testing requirements and is safe for transport.
UN38.3 Certification Testing
All lithium chemistries must receive certification to show that they pass environmental, electrical, and mechanical safety requirements.
There are 8 tests required for UN38.3 certification:
- T1 - Altitude Simulation: low-pressure simulation (primary & secondary cells/batteries)
- T2 - Thermal Test: integrity testing when batteries undergo extreme and rapid temperature changes (primary & secondary cells/batteries)
- T3 - Vibration Test: vibration simulation that may be experienced during transportation (primary & secondary cells/batteries)
- T4 - Shock Test: shock test/vibration simulation during transportation (primary & secondary cells/batteries)
- T5 - External Short Circuit Test: external short circuit simulation (primary & secondary cells/batteries)
- T6 - Impact Test: impact and crush simulations on the cell's casing (primary & secondary cells)
- T7 - Overcharge Test: overcharge simulation on rechargeable batteries (secondary batteries)
- T8 - Forced Discharge Test: forced discharge simulations (primary & secondary cells)
Sample batteries undergo test simulations to determine manufacturability and safe design parameters for battery components. The UN38.3 standard has 4 classifications in which lithium-based batteries will undergo testing based on how the battery becomes transported.
UN 3090 and UN 3480
This classification applies to all lithium batteries and lithium-ion batteries that are shipped as cells or as completed batteries outside of products. It also applies to cell/battery consignments, modules, incomplete battery subassemblies, power packs, or power banks that are shipped in a separate package that is not inside a device. The separate package may be in the same consignment or shipment container with the devices.
UN 3091 and UN 3481
This classification covers all lithium and lithium-ion batteries that are shipped inside the devices. It also applies to batteries placed beside the device in the same shipment package. A shipment where the device contains the battery already pre-installed and has two spare batteries included inside the same packaging will also fall into this category.
Testing Requirements and Timetable
Lithium-based batteries undergoing UN38.3 testing certification will require a certain number of packs to be sent to an approved independent testing laboratory. Typically, about 16 battery packs will be sent to the laboratory as they will generate a UN38.3 report and summary explaining the test results.
The test report will be about 10 pages long and provides comprehensive technical details. The test summary is one page that focuses on 10 specific topics. The report will comprise a sample description that has the sample name, the battery's rated capacity, nominal voltage, charge current, limited charge voltage, maximum continuous charge current, cut-off voltage, end charge current, and maximum discharge current. The sample description also includes the applicant's name and address, the battery manufacturer's name and address, the number of submitted packs that underwent testing, the receiving date, the test completion date, and other details.
The rest of the test report will provide the standard used for the testing, the test item details, the test methods and requirements, the test procedure, and the main test apparatus. It will also include the test data, the test conclusion, and photos of the samples. The test summary can be made available to the shipper when they request it. The test report becomes the certificate as it only applies to the original supplier of the battery or cell.
Testing may take 4 weeks up to 6 weeks. This time schedule may be extended if the batteries or cells fail the certification process and need to be redesigned to undergo the testing again.
If a customer redesigns the battery or cell after the testing, the lithium-based battery or cell will have to undergo testing again to receive new certification. If there are no design changes to the lithium battery or cell, only a new report is generated.
The certification cannot pass between suppliers. If you switch to a different supplier even though the battery design stays the same, the new supplier will need to receive certification for the batteries. The test report will not have the company name or address on the old report or summary. Also, it is possible that the new supplier performs some type of change to the battery chemistry, materials, or other components that slightly differs from the original design. These slight changes will not match the existing test information.
The UN38.3 test certification only applies to lithium-based batteries and cells. Other types of batteries may undergo testing that is specific to their battery chemistry and components. Yet, those tests do not fall within this UN standard.