What IEC 62133-2 covers
IEC 62133-2 sets safety requirements and tests for portable sealed secondary lithium cells, and for batteries made from them, used in portable applications. In plain terms, it asks whether a rechargeable lithium cell or pack stays safe in intended use and reasonably foreseeable misuse: charging within and beyond normal limits, short circuits, drops, heat and mechanical abuse. It applies to the small lithium-ion cells found in smart glasses temples - typically about 85 to 235 mAh in total across both temples - and to the cell in a charging case.
The standard sits in a family of battery and product safety documents. UN 38.3 covers transport. The safety standard for the finished audio and communication product, EN 62368-1 in Europe, deals with the whole device and commonly looks to battery safety evidence such as an IEC 62133-2 report. EU Battery Regulation 2023/1542 adds requirements for the battery as a product. The test lab decides how they fit together for a given pair.
The main tests
Tests are applied to cells, to batteries or to both, depending on the clause. Parameters, sample counts and pass criteria are set in the edition of the standard the lab applies, and some markets add national differences. The table summarises the main test types.
| Test type | What it checks | Level |
|---|---|---|
| Continuous charging | Long charging at the specified conditions without fire or leakage | Cells |
| Vibration | Mechanical robustness of cells and connections | Batteries |
| Case stress at high temperature | Whether a pack housing deforms and exposes parts when hot | Batteries |
| External short circuit | Behaviour when the terminals are shorted | Cells and batteries |
| Free fall | Drops during handling and use | Cells and batteries |
| Thermal abuse | Exposure to elevated temperature | Cells |
| Crush | Mechanical crushing without fire or explosion | Cells |
| Overcharge of battery | Protection against charging beyond limits | Batteries |
| Forced discharge | Cell driven into reverse | Cells |
Beyond the tests, the standard asks the cell maker to declare the charging limits - upper charge voltage, charge current and the temperature range for charging - and expects the device to respect them. For smart glasses this links the cell to the charge circuit in the temple: a charge circuit that pushes a cell beyond its declared limits can undermine a valid cell report.
What buyers request
Buyers typically ask for a small, consistent battery file. Request it early, because a missing or mismatched report found at listing stage can hold a launch for weeks.
- Cell report: an IEC 62133-2 test report for the cell model fitted, often issued as a CB test report under the IECEE scheme, with the lab name and report number.
- Battery or pack report: where cells are assembled into a pack with a protection circuit, a report covering the pack level tests.
- Cell spec sheet: nominal voltage, capacity, Wh, charge limits and operating temperatures, matching the report.
- UN 38.3 summary: transport evidence for the same cell and pack, covered in UN 38.3 for smart glasses.
- Charge circuit statement: how the temple charge circuit keeps within the declared limits, confirmed by the partner plant.
Marketplaces and retailers may ask for the same documents in their own formats, and some request the full report rather than a certificate page. Keeping the file complete from the first batch avoids repeated requests. The general certification picture by market is in the certifications checklist.
Reading a report critically
A report is only useful if it covers the cell inside the product. Common problems are reports for a sister cell with a different capacity, reports that cover the bare cell when the product uses a pack with its own protection circuit, reports on an old edition the buyer's lab will not accept, and reports whose holder is not the cell maker named on the spec sheet. Each of these is quick to spot with a checklist.
It also helps to read what the report does not say. A cell report shows that the cell type passed the tests on the samples submitted; it does not show that every cell in a production lot is identical to those samples, that the temple housing protects the cell from pressure, or that the charge circuit in the glasses behaves as declared. Those points are covered by change control, incoming checks on cell lots, the end-product safety assessment and inspection of the finished pairs. Treat the report as one piece of evidence in a chain, not as a statement about the finished product. A short cover note in the document file that maps each report to the part it covers saves time for every reviewer downstream.
- Model and rating: cell model, capacity and Wh on the report match the spec sheet and the marking on the cell.
- Level: the report covers the item as fitted - cell, pack or both.
- Edition and differences: the edition and any national differences match what your target markets accept.
- Holder and factory: the report holder and production site match the cell supplier on the bill of materials.
- Charge limits: declared limits match the temple charge circuit settings.
The same checklist applies to charging cases, which carry their own cell; see charging cases for smart glasses.
Where IEC 62133-2 fits in the program
For catalog models, IEC 62133-2 and UN 38.3 files usually already exist for the cell in the design, and the job is to verify that they match. For custom temples with a new cell or pack, tests should be booked at the engineering sample stage so reports are ready before the batch ships. Laboratory testing for the radio approvals, such as FCC and CE, typically takes about 3 to 6 weeks per lab and scope, and battery testing is best run in parallel rather than after. A change of cell during production restarts the battery file, which is why cell changes are controlled in writing.
The desk collects and checks the battery file with the rest of the program documents and compares cell markings against it at inspection. The process is on compliance and certifications, sample and batch ranges are on MOQ and lead time, and requests can be sent through the quote form. Final decisions on which standards apply in a market rest with your test lab and counsel.