Nail Penetration – UN 38.3

What Is Nail Penetration — UN 38.3?

The nail penetration test is an abuse test in which an artificial internal short circuit is created by driving a conductive nail of defined diameter into a fully charged cell at a controlled speed. It is used to examine thermal-runaway behaviour.

Purpose of Nail Penetration — UN 38.3

The purpose is to evaluate the energy release and the tendency toward thermal runaway when a sudden internal short circuit occurs within the cell.

Which Products Is Nail Penetration — UN 38.3 Applied To?

Lithium-ion cells
Electric vehicle cells
Energy storage cells

In Which Sectors Is Nail Penetration — UN 38.3 Used?

BatteryElectric VehicleAutomotiveEnergyElectronics

Standards Related to Nail Penetration — UN 38.3

UN 38.3Transport safety tests on lithium batteries test

Nail Penetration — UN 38.3 Conditions

Nail diameter: Defined in the specification; typically 3–8 mm
Penetration speed: Fixed speed defined in the specification
Penetration depth: So as to pass completely through the cell, or to the defined extent
Safety: An explosion-protected room, gas venting and an extinguishing system are mandatory

Equipment for Nail Penetration — UN 38.3

Nail penetration test rig
Force and displacement measurement
Explosion-protected test room
High-speed temperature recording and thermal camera
Gas analysis system

Sample Requirements for Nail Penetration — UN 38.3

The specimen is taken into the test fully charged
The test is single-use and high-risk
The cell chemistry and energy content must be known in advance
The number of specimens is set out in the specification

Duration of Nail Penetration — UN 38.3

The penetration event lasts seconds; together with preparation, observation and cooling, one working day is planned.

Nail Penetration — UN 38.3 Procedure

1The specimen is fully charged, and its mass and voltage are recorded.
2Thermocouples are placed on the surface and the specimen is placed in the chamber.
3The nail is driven in at the defined speed and depth.
4Voltage, temperature and gas release are monitored continuously.
5Whether thermal runaway occurs and the peak temperature are recorded.
6Mass loss and physical condition are assessed after cooling.

Nail Penetration — UN 38.3 Acceptance Criteria

This test is generally conducted for characterisation purposes rather than a pass/fail criterion. If a criterion is applied, it is defined in the specification as the absence of fire and explosion.

Evaluation of Results

Peak temperature, rate of temperature rise, gas quantity and whether thermal runaway occurred are evaluated. Results depend strongly on cell chemistry.

Nail Penetration — UN 38.3 Report

Applied specification
Nail diameter, speed and depth
Initial state of charge and energy content
Temperature and voltage records
Thermal-runaway observation, 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

China GB 38031 (vehicle battery)
OEM development specifications

Batarya Testleri — What Does This Testing Field Cover?

The section below describes the field that the Nail Penetration 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 Nail Penetration — UN 38.3

Is the nail penetration test included in IEC 62133 or UN 38.3?

No. This test is not defined under UN 38.3 or IEC 62133-2. It appears in national regulations such as China's GB 38031 and in OEM development specifications. Which specification it will follow must therefore be clarified in advance.