Thermal Propagation Test — UNECE R100 / UL 2580 / GB 38031

What Is Propagation?

The thermal propagation test is a test in which, after thermal runaway is triggered in a single cell within a module or pack, it is evaluated whether the event spreads to neighbouring cells and beyond the enclosure.

Purpose of Propagation

The purpose is to verify that the battery design can contain a single-cell failure and can issue a warning before a hazard arises for occupants or the surroundings.

Which Products Is Propagation Applied To?

Electric vehicle battery modules and packs
Energy storage systems
Industrial battery systems

In Which Sectors Is Propagation Used?

BatteryElectric VehicleAutomotiveEnergyElectronics

Standards Related to Propagation

UNECE R100electric vehicle and battery safety test
UL 2580Safety in electric vehicle batteries test
GB 38031
IEC 62619lithium battery safety in industrial applications test
UN 38.3Transport safety tests on lithium batteries test
IEC 62133Safety in portable cells and batteries test
IEC 62620industrial lithium cells and batteries test
UL 1642safety in lithium cells test
UL 2054Safety in home and commercial use batteries test
ISO 12405Test conditions for electric vehicle lithium battery packs test

Propagation Conditions

Triggering: Thermal runaway is initiated in a single cell by heating, overcharge or nail penetration
Trigger position: The worst-case position is chosen (generally the centre or a corner cell)
Monitoring: Neighbouring cell temperatures, enclosure surface and gas-vent points
Observation period: Defined in the specification; typically on the order of hours after the event

Equipment for Propagation

Large-volume explosion-protected test room
Multi-channel (tens of channels) temperature recording
Gas analysis and venting system
Thermal camera and multi-camera video
Extinguishing system

Sample Requirements for Propagation

The specimen must be a real module or pack
It is taken into the test fully charged and with the BMS connected
The position of the cell to be triggered must be documented with its rationale
The test is single-use and costly

Duration of Propagation

Together with preparation, instrumentation, testing and observation, one to two weeks are typically planned.

Propagation Procedure

1The module or pack is instrumented; tens of thermocouples are placed.
2The BMS is connected and data logging is set up.
3The specimen is fully charged and placed in the test room.
4Thermal runaway is triggered in the selected cell.
5Neighbouring cell temperatures, enclosure condition and gas release are monitored.
6Residue and the extent of propagation are assessed at the end of the observation period.

Propagation Acceptance Criteria

The acceptance criterion is defined in UNECE R100 and related standards: no hazardous level of heat or gas entering the passenger compartment, the system issuing a warning within the specified time, and flame not spreading beyond the enclosure.

Evaluation of Results

How many cells the propagation reached, the enclosure surface temperature and the timing of the BMS warning are evaluated together. The effectiveness of the thermal barriers in the design becomes apparent in this test.

Propagation Report

Applied standard and regulation
Triggering method and cell position
Recording of all temperature channels
Extent of propagation and timeline
BMS warning records, video and photographs

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

UNECE R100 Part II
GB 38031
EU Battery Regulation

Batarya Testleri — What Does This Testing Field Cover?

The section below describes the field that the Propagation test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Battery testing answers three separate questions, each with its own body of standards: can the battery be transported, is it safe in use, does it deliver the declared performance? These three questions are often confused with one another, and the confusion has commercial consequences — a market cannot be entered with a transport report, and a shipment cannot be made with a product safety report.

On the transport side, UN 38.3 is a mandatory gate; a battery without that evidence cannot be shipped. On the safety side the application determines what applies: IEC 62133-2 for portable products, IEC 62619 and IEC 63056 for industrial and energy storage applications, UNECE R100, UL 2580 and ISO 6469 for electric vehicles. On the performance side, capacity, internal resistance, cycle life, self-discharge, charge acceptance and temperature-dependent behaviour are measured.

The distinction of LEVEL is essential in this family and is the subject that causes the most argument in the supply chain. Cell, module and pack are assessed separately; a certificate obtained for a cell does not demonstrate the conformity of the pack. Alongside the cells, the behaviour of the pack is determined by the battery management system, the cooling design, the mechanical structure, the interconnection arrangement and insulation coordination. Putting the cell supplier's report into the pack file is a common but inadequate approach.

Thermal runaway and its propagation are the most critical subject in the field. A lithium cell may enter a self-sustaining chemical reaction when damaged or overheated; at that point removing the heat from outside is usually not possible. Modern standards therefore treat thermal runaway of a single cell as an UNAVOIDABLE fault scenario and change the question: does the event propagate to neighbouring cells, what does it release outside the pack, and how much time is left for the user to escape?

In this field the battery management system is assessed not as an electronic board but as a SAFETY FUNCTION. It is shown that overcharge, overdischarge, overcurrent and overtemperature protections actually operate, that the system falls to the safe side in a fault, and that its software has been verified. In industrial and vehicle applications this assessment is tied to functional safety frameworks.

The regulatory side is becoming rapidly more demanding. Battery Regulation (EU) 2023/1542 goes beyond safety and introduces obligations for carbon footprint declaration, recovered content ratio, durability and capacity declaration, the battery passport, and removability for portable batteries. This takes the scope of testing beyond classical safety tests.

Method groups in this field

Electrical abuse
Overcharge, overdischarge, external short circuit, forced discharge and unbalanced charging. This is where it is seen whether the protection circuits actually work.
Mechanical abuse
Vibration, shock, crush, penetration, free fall and tipping. It is monitored whether internal short circuit conditions arise.
Thermal tests
Temperature cycling, thermal shock, high temperature storage, fire exposure and thermal runaway propagation.
Environmental tests
Humidity, low pressure, salt spray and, where required, immersion; these come to the fore in vehicle and outdoor applications.
Performance measurements
Capacity, energy and power, internal resistance, efficiency, cycle life, calendar life and temperature-dependent behaviour.
BMS verification
Verification of protection thresholds, the cell balancing function, communications and fault response.

Commonly confused in this field

UN 38.3 is not a product safety certificate; it only demonstrates transport conformity.
A cell certificate does not demonstrate pack conformity. The pack is assessed separately with its own architecture.
Two packs built from the same cell give different results; cooling, interconnection and mechanical structure are decisive.
A performance test is not a safety test. A cycle life report does not satisfy safety requirements.
For an electric vehicle battery, a UL 2580 report and UNECE R100 approval are not the same thing; one is a standards assessment, the other a type approval regime.
A vehicle battery moved into a second-life application enters a new usage profile; the earlier assessment does not carry over directly.

Which decisions these results support

Transport conformity and the test summary for shipment
Product safety declaration and market access
Performance, durability and carbon footprint declarations under the Battery Regulation
Assessing the impact of a cell supplier or BMS change
Site acceptance processes for an energy storage system

Related Tests

Frequently Asked Questions About Propagation

Why is the propagation test so expensive and long?

A real module or pack is sacrificed as single-use, tens of measurement channels are set up, and a large-volume explosion-protected room is required. Planning and cost are therefore assessed separately at the quote stage.