What UN 38.3 is and why it applies
UN 38.3 is a section of the UN Manual of Tests and Criteria that sets transport safety tests for lithium cells and batteries. Dangerous goods rules for air, sea and road refer to it: a lithium cell or battery type that has not passed UN 38.3 cannot normally be shipped as a regular consignment, whether it travels on its own, packed with equipment or contained in equipment. Smart glasses contain lithium-ion cells in the temples - typically about 85 to 235 mAh in total across both temples - so every program needs UN 38.3 evidence for those cells, and for any charging case or spare battery.
UN 38.3 is about transport, not about everyday product safety. A cell that passes UN 38.3 has shown it can survive the pressures, temperatures, vibration and mechanical stress of shipping without leaking, venting, rupturing or catching fire. Product safety in use is covered by other standards such as IEC 62133-2, discussed in IEC 62133-2 for wearable batteries. Buyers usually need both.
The eight tests
The tests simulate the conditions a battery may meet in transport. Test parameters and pass criteria are set in the UN Manual; the test lab applies the edition in force. Which tests apply depends on whether the item is a cell or a battery and whether it is rechargeable.
| Test | What it simulates | Applies to |
|---|---|---|
| T.1 Altitude simulation | Low pressure in an unpressurised cargo hold | Cells and batteries |
| T.2 Thermal test | Rapid swings between high and low temperature | Cells and batteries |
| T.3 Vibration | Vibration during road, rail, sea and air transport | Cells and batteries |
| T.4 Shock | Shocks from handling and impacts | Cells and batteries |
| T.5 External short circuit | A short across the terminals at elevated temperature | Cells and batteries |
| T.6 Impact or crush | Mechanical abuse that could cause an internal short | Cells |
| T.7 Overcharge | Charging beyond normal limits | Rechargeable batteries |
| T.8 Forced discharge | A cell driven into reverse in a pack | Cells |
The test summary buyers ask for
Since the dangerous goods rules began requiring it, anyone in the supply chain - the shipper, the forwarder, a marketplace or a fulfilment centre - can ask for a UN 38.3 test summary. It is a short document, separate from the full test report, that identifies who made the cell or battery, the type tested, its rated capacity or energy, the lab and report reference, the list of tests passed and a reference to the UN Manual edition used. A summary that does not match the cell inside the product is the most common document problem in practice.
- Model match: the cell or battery model on the summary matches the cell spec sheet and the marking on the cell.
- Rating match: capacity and Wh match the spec sheet; Wh equals nominal voltage multiplied by capacity in Ah.
- Level match: the summary covers the item as shipped - cell, battery pack with protection circuit, or both.
- Current edition: the summary refers to an edition of the UN Manual accepted by the carrier.
For smart glasses, a common structure is a cell summary from the cell maker plus a battery summary for the assembled pack with its protection circuit, where the pack is a separate item. Charging cases need their own summary for the case battery. A brand's document file should keep all of them together, with the cell spec sheets.
Who issues the summary matters as well. It is normally provided by the cell or battery maker, or by the party that assembled the pack, and it is passed down the chain with the goods. A brand selling under its own label does not usually test the cells itself, but it is expected to be able to produce the summary on request. Keeping a current copy for each cell model in the range, filed by model and supplier, is the simplest way to meet that expectation.
When a change needs retesting
UN 38.3 results belong to a cell or battery type. A change that could affect test results generally needs a new test: a different cell supplier, a change of chemistry or capacity, a new pack design or protection circuit, or a change in the way cells are connected. A change of temple colour does not. Swaps of cells during production, often for availability reasons, are where programs most often end up with documents that no longer match the product.
- Freeze the cell. Fix the cell model and supplier on the golden sample.
- Collect the files. Cell and pack test summaries, full reports on request, cell spec sheets.
- Control changes. No cell or pack change without written approval and new documents.
- Check at inspection. Compare cell markings on sampled pairs with the documents before shipment.
This document check is part of how the desk runs testing and inspection for each lot.
From UN 38.3 to shipping
Passing UN 38.3 is a precondition, not the whole shipping answer. Smart glasses with cells inside ship as lithium ion batteries contained in equipment, UN3481. By air, smaller batteries can typically use PI 967 Section II, which applies to cells of no more than 20 Wh and batteries of no more than 100 Wh, with a limit of 5 kg net of lithium batteries per package on passenger aircraft, a lithium battery mark and a statement on the air waybill. Temple cells sit far below those energy limits, but the shipper still has to meet the packaging, marking and documentation conditions. IATA recommends shipping at a state of charge of no more than 30 percent; for PI 967 that is a recommendation rather than a requirement.
These rules are summarised in shipping wearables with batteries, but they change between editions and carriers can apply stricter rules. Confirm with your forwarder before booking, and see logistics and shipping for how the desk prepares the file.
UN 38.3 in the program plan
UN 38.3 testing usually sits with the cell maker, and catalog models typically come with existing summaries. Custom cells or packs need new tests, which should be planned into the sample stage so documents are ready before the first batch ships. Sample and batch timings are typical reference ranges on MOQ and lead time, confirmed in writing per program, and the brief can be sent through the quote form.