UL 1642 – Standard for safety – lithium batteries
UL 1642 is a safety standard for primary (non-rechargeable) and secondary (rechargeable) lithium batteries. The standard defines construction requirements, test procedures, and marking obligations with the objective of reducing the risk of fire or explosion when lithium batteries are used in products. The standard distinguishes between technician-replaceable and user-replaceable batteries and specifies distinct safety requirements for both categories.
| Aspect | Details |
|---|---|
| Scope | Primary and secondary lithium batteries (metallic lithium, lithium alloys, lithium-ion) as power sources in products |
| Test subject | Individual cells and battery packs – technician-replaceable and user-replaceable |
| Test scope | 11 individual tests: 3 electrical, 4 mechanical, 3 environmental, 1 fire exposure test |
| Certification document | UL certification / UL test report |
| Related standards | IEC 62133-2, UN 38.3, UL 2054 |
What UL 1642 covers
UL 1642 governs the safety evaluation of lithium batteries for use in products. The standard defines three requirement areas.
Construction requirements cover enclosure strength, electrolyte protection, and safeguards against abnormal charging currents. User-replaceable batteries are subject to more stringent enclosure requirements.
Test procedures are organized into four categories:
- Electrical tests: Short circuit test, abnormal charging test, forced-discharge test
- Mechanical tests: Crush test, impact test, shock test, vibration test
- Environmental tests: Heating test, temperature cycling test, low-pressure test
- Fire exposure test: Projectile test
Marking obligations define mandatory information on batteries and packaging. Primary batteries require warning labels regarding fire and burn hazards. Lithium coin cells require additional ingestion warnings.
Where UL 1642 applies – and where it does not
UL 1642 applies to lithium batteries containing metallic lithium, lithium alloys, or lithium-ion. The standard covers individual cells as well as multi-cell configurations in series, parallel, or combination arrangements.
The standard distinguishes two replacement categories:
- Technician-replaceable batteries: Replacement by trained service personnel only
- User-replaceable batteries: Replacement by the end user
User-replaceable batteries are subject to more stringent requirements in mechanical tests.
Not covered by UL 1642:
- Toxicity risks from battery ingestion
- Injury risks from opening batteries
- Secondary lithium cells are not considered user-replaceable
When You Need UL 1642
UL 1642 is required in the following scenarios:
- UL certification for the North American market (USA, Canada)
- Lithium batteries as components in UL-certified end products
- Product approval for import and sale in North America
- Demonstration of battery safety to market surveillance authorities
Final acceptance of batteries depends on their use in a complete product. The end product must meet the applicable product requirements.
For authoritative information on certification obligations, contact the responsible testing body.
Where UL 1642 Applies
UL 1642 is primarily relevant for the North American market (USA and Canada). The standard is published by Underwriters Laboratories Inc. (UL) and is a prerequisite for UL certification of lithium batteries.
Internationally, UL 1642 is recognized as a reference standard for the safety evaluation of lithium batteries. The standard is frequently used in conjunction with IEC 62133-2, particularly for products intended for both North American and international markets.
When UL 1642 becomes relevant in the product lifecycle
UL 1642 becomes relevant at several stages of the product lifecycle:
- Construction and design: Enclosure and protection circuit requirements influence battery design
- Testing and certification: Test specimen selection, conditioning, and execution of the 11 test procedures
- Production: Compliance with construction requirements during series manufacturing
- Marking: Application of prescribed markings on batteries and packaging
- Market surveillance: Ongoing conformity with certification requirements
How UL 1642 testing works
The testing process according to UL 1642 follows a structured sequence. Testing begins with the determination of battery type and test specimen selection. After conditioning of the test specimens, tests are conducted in four categories.
Test overview
Battery sample selection and conditioning
Determination of battery type (primary/secondary, technician-/user-replaceable). Battery sample selection according to Table 6.1 or 6.2. Primary batteries are discharged through resistive loads. Secondary batteries undergo charge-discharge cycling at 25 °C. For lithium-ion cells, special preconditioning at the boundaries of the Cell Operating Region is required before the heating test.
Electrical tests
Short-circuit test: Short circuit through a defined low-resistance load at two ambient temperatures. Abnormal charging test: Separate procedures for primary and secondary cells with defined charging and current conditions. Forced-discharge test: Forced discharge in series multi-cell applications.
Mechanical tests
Crush test: Compression by hydraulic ram until a defined force is reached. Impact test: Drop weight over a bar onto the battery. Shock test: Acceleration pulses in three axes. Vibration test: Harmonic vibration with frequency sweep. Simplified orientation requirements apply to lithium-ion cells.
Environmental and fire tests
Heating test: Heating at a defined rate to a target temperature. Temperature cycling test: 10 cycles between high and low temperatures. Low-pressure test: Simulation of altitude conditions. Projectile test: Exposure to open flame with an octagonal wire cage as a containment and measurement element.
Evaluation and marking
Evaluation of all test results against the defined acceptance criteria. Primary criterion: No fire or explosion. Additionally for certain tests: No impermissible leakage or venting. Final verification of marking requirements on batteries and packaging.
Frequently asked questions about UL 1642
Technician-Replaceable vs. User-Replaceable Batteries
Technician-replaceable batteries are intended for replacement by trained service personnel. User-replaceable batteries can be changed by the end user. User-replaceable batteries are subject to more stringent requirements in mechanical tests (crush, impact). Secondary lithium cells are generally not considered user-replaceable.
Test Scope Under UL 1642
UL 1642 comprises 11 individual tests in four categories: Three electrical tests (short circuit, abnormal charging, forced discharge), four mechanical tests (crush, impact, shock, vibration), three environmental tests (heating, temperature cycling, low pressure), and one fire exposure test (projectile test).
Cell Operating Region for Lithium-Ion Cells
The Cell Operating Region is the safe operating range of a lithium-ion cell as specified by the cell manufacturer. It is defined by three parameters: voltage range, current range, and temperature range. Before the heating test according to UL 1642, special preconditioning at the boundaries of this Operating Region is performed.
Acceptance Criteria Under UL 1642
The primary acceptance criterion for all tests is: No fire and no explosion. For certain tests (shock, vibration, temperature cycling, low pressure), additional criteria for venting and leakage apply, based on defined mass loss thresholds.
UL 1642 Compared to IEC 62133-2
UL 1642 is primarily relevant for the North American market (USA, Canada) and is a prerequisite for UL certification. IEC 62133-2 is an international standard for portable secondary lithium batteries. For products distributed in both North America and international markets, both standards may be relevant. For authoritative information, contact the responsible testing body.
VRI supports you in preparing and conducting tests according to UL 1642. Contact us for an initial consultation.
Ralf Isermeyer
Geschäftsführer / CEO
This page summarizes UL 1642 in accessible form. It is intended for orientation and decision support.
Only the official standard (UL 1642, Fifth Edition, 2012, revised June 2015) is legally authoritative. For binding information, consult the responsible testing body or a certification expert.
Last Updated: 2026-02-16 | Basis: UL 1642 Fifth Edition (2012, Rev. 2015) | Source: VRI GmbH