prEN IEC 62660-2:2026

• Status: Not Published
• Publication Date: 02-Mar-2028
• ICS: 29.220.20 - Acid secondary cells and batteries
• ICS: 43.120 - Electric road vehicles
• Technical Committee: CLC/TC 21X - Secondary cells and batteries
• Current Stage: 4020 - Enquiry circulated - Enquiry
• Start Date: 25-Sep-2026
• Due Date: 30-Jun-2027
• Completion Date: 25-Sep-2026
• Ref Project: oSIST prEN IEC 62660-2:2026 - Secondary lithium-ion cells for the propulsion of electric road vehicles - Part 2: Reliability and abuse testing

• Revises: EN IEC 62660-2:2019 - Secondary lithium-ion cells for the propulsion of electric road vehicles - Part 2: Reliability and abuse testing
• Effective Date: 27-Jan-2026

prEN IEC 62660-2:2026 is a CENELEC/IEC draft standard for secondary lithium-ion cells used to propel electric road vehicles. It specifies reliability and abuse test procedures for cells and cell blocks for battery electric vehicles (BEV) and hybrid electric vehicles (HEV), and it gives a standard way to describe the test results for use in battery system and battery pack design.

What does prEN IEC 62660-2:2026 specify?

prEN IEC 62660-2:2026 specifies test procedures to observe the reliability and abuse behaviour of secondary lithium-ion cells and cell blocks used for propulsion of electric vehicles. The document is aimed at creating basic test data for battery systems and battery packs, not at assigning pass-fail criteria.

The document is organized into these main parts:

Part	What it covers
Clause 1	Scope
Clause 2	Normative references
Clause 3	Terms and definitions
Clause 4	Test conditions
Clause 5	Electrical measurement
Clause 6	Reliability and abuse tests
Clause 7	Description of test results
Annex A	Informative selective test conditions for capacity testing

The scope includes BEV and HEV applications, and it also allows cell blocks to be tested as an alternative to single cells when agreed between the cell manufacturer and the customer. The document is built for testing and reporting, so users can compare results in a consistent way when they design or evaluate battery systems.

What are the key requirements of prEN IEC 62660-2:2026?

prEN IEC 62660-2:2026 focuses on how to prepare specimens, how to measure them, how to run the tests, and how to record the results. In practice, the standard is most useful as a test plan for laboratories and as a common basis for customer-manufacturer agreements.

Test conditions and measurement setup

Clause 4 sets the general test conditions. Cells are tested at room temperature unless stated otherwise, and the document defines room temperature as 25 °C ± 2 K.

Clause 4 also requires the test installation and the fixation and wiring method to be reported. This matters because the mounting arrangement can change vibration, shock, heating, or short-circuit behaviour.

The clause also sets measurement expectations for voltage, current, temperature, and other values. It requires suitable instrument accuracy and temperature measurement at a location that best reflects the cell or cell block temperature. In practice, this means the test report needs to show how the readings were taken, not just the final numbers.

Thermal stabilization is also defined in Clause 4. The cell is soaked at the specified ambient temperature before testing, and the test may begin early only when stabilization has been reached. This prevents starting a test with an uncontrolled internal temperature.

Electrical preparation before testing

Clause 5 defines how a cell is prepared before electrical measurement and before the test sequence. The cell is first discharged and then charged according to the manufacturer’s declared charging method.

Clause 5 also covers capacity measurement and state of charge (SOC) adjustment. The capacity test uses defined discharge conditions, while SOC adjustment prepares the cell for later tests at the required charge level. For the user, this means the test result depends on correct preconditioning, so the starting state must be controlled and documented.

Annex A adds selective capacity-test conditions. It gives extra test combinations that may be chosen by agreement between the cell manufacturer and the customer.

Reliability and abuse tests

Clause 6 groups the main test families:

• Mechanical tests:
  • vibration
  • mechanical shock
  • crush
• Thermal tests:
  • high temperature endurance
  • temperature cycling
• Electrical tests:
  • external short circuit
  • overcharge
  • forced discharge

These tests are meant to show how the cell responds to vehicle-like mechanical loads, elevated and cycling temperatures, and electrical abuse conditions. In practice, they help users compare designs and collect evidence for battery system and battery pack development.

Clause 6 also requires the test sample details to be reported, including the number and type of samples. Tests are performed on cells that are not more than six months old, and the one-hour observation period at the end of each test is part of the procedure unless stated otherwise.

Test result reporting

Clause 7 does not use pass-fail criteria. Instead, it standardizes how outcomes are described, using labels such as no effect, deformation, venting, leakage, smoke, rupture, fire, and explosion.

That approach matters because different users may judge the same physical event in different ways unless the report language is fixed. The clause also allows photos or similar materials to support the description.

What terms does prEN IEC 62660-2:2026 define?

• battery electric vehicle (BEV) - An electric vehicle that uses only a traction battery as the propulsion power source.
• cell block - A group of cells connected in parallel, with or without protective devices, and not yet fitted with final housing, terminal arrangement, and electronic control device.
• hybrid electric vehicle (HEV) - A vehicle that uses both a rechargeable energy storage system and a fuelled power source for propulsion.
• rated capacity - The capacity value of a cell in ampere hours, determined under specified conditions and declared by the cell manufacturer.
• reference test current - The current used as the reference for tests, expressed from rated capacity and the time base.
• state of charge (SOC) - The quantity of electricity stored in a cell, expressed as a percentage of rated capacity.
• secondary lithium-ion cell - A rechargeable single cell whose energy comes from lithium-ion insertion and extraction between the negative and positive electrodes.
• room temperature - 25 °C ± 2 K.

Who uses prEN IEC 62660-2:2026?

prEN IEC 62660-2:2026 is used by cell manufacturers, battery system and battery pack designers, test laboratories, and customers who specify acceptance or validation tests for electric-vehicle cells. It is also relevant to organizations working with BEV and HEV traction batteries.

These users apply the document when they need a common test method for reliability and abuse behaviour, when they agree on test conditions such as SOC or specimen type, and when they write or read test reports. The standard is especially useful where repeatable test preparation and result description matter more than a simple pass-fail outcome.

What changed in prEN IEC 62660-2:2026 from the previous edition?

prEN IEC 62660-2:2026 is the third edition and cancels and replaces the second edition published in 2018. The document states these technical changes:

• the forced discharge test procedure has been clarified
• cell block has been added to the scope
• the option of temperature cycling with electrical operation has been deleted
• the overcharge test conditions have been revised

Which standards are used with prEN IEC 62660-2:2026?

Reference	What it contributes
IEC 60068-2-64:2008	Broadband random vibration test guidance used for the vibration method
ISO/TR 8713:2019	Vocabulary for electrically propelled road vehicles
ISO 16750-3:2023	Mechanical load conditions for road-vehicle electrical and electronic equipment
ISO 16750-4:2023	Climatic load conditions for road-vehicle electrical and electronic equipment
ISO 12405-4:2018	Associated test specification for lithium-ion traction battery packs and systems, focused on performance testing
IEC 62660-1:2018	Companion part for performance testing of lithium-ion cells for electric vehicle application
IEC 62660-3:2022	Companion part for safety requirements of lithium-ion cells for electric vehicle application
IEC 61434:1996	Background reference for the designation of current

What does the prEN IEC 62660-2:2026 document contain?

The document contains the test conditions, electrical measurement guidance, and the full set of reliability and abuse test methods for lithium-ion cells used in electric road vehicles. It also includes figures that illustrate temperature measurement, vibration spectra, and crush test arrangements.

Its tables provide the discharge conditions, vibration profile data, mechanical shock parameters, temperature-cycling schedule, result-description categories, and additional capacity-test conditions in Annex A. In practice, these tables are the parts users consult when setting up tests, writing procedures, and preparing reports.

Clause 6 is the main practical section because it defines the mechanical, thermal, and electrical abuse tests. Clause 7 then converts the observed outcomes into standardized report language, which is what makes the document useful for design reviews, laboratory reporting, and technical comparison.

SLOVENSKI STANDARD
01-november-2026
Sekundarni litij-ionski členi za pogon električnih cestnih vozil - 2. del: Preskušanje
zanesljivosti in izrabljivosti
Secondary lithium-ion cells for the propulsion of electric road vehicles - Part 2: Reliability
and abuse testing
Lithium-Ionen-Sekundärzellen für den Antrieb von Elektrostraßenfahrzeugen - Teil 2:
Zuverlässigkeits- und Missbrauchsprüfung
Eléments d'accumulateurs lithium-ion pour la propulsion des véhicules routiers
électriques - Partie 2: Essais de fiabilité et de traitement abusif
Ta slovenski standard je istoveten z: prEN IEC 62660-2:2026
ICS:
29.220.20 Kislinski sekundarni členi in Acid secondary cells and
baterije batteries
43.120 Električna cestna vozila Electric road vehicles
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

21/1312/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 62660-2 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-09-25 2026-12-18
SUPERSEDES DOCUMENTS:
21/1282/CD, 21/1297A/CC
IEC TC 21 : SECONDARY CELLS AND BATTERIES
SECRETARIAT: SECRETARY:
France Mr Yves BOUDOU
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):

TC 69,ISO/IEC JTC 1/SC 25
ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
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This document is still under study and subject to change. It should not be used for reference purposes.
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the final stage for submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Secondary lithium-ion cells for the propulsion of electric road vehicles - Part 2: Reliability and
abuse testing
PROPOSED STABILITY DATE: 2030
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IEC CDV 62660-2 © IEC 2026
CONTENTS
CONTENTS . 4
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 9
4 Test conditions . 11
4.1 General . 11
4.2 Measuring instruments . 11
4.2.1 Range of measuring devices . 11
4.2.2 Voltage measurement . 11
4.2.3 Current measurement . 11
4.2.4 Temperature measurements . 11
4.2.5 Other measurements . 12
4.3 Tolerance . 12
4.4 Thermal stabilization . 12
5 Electrical measurement . 12
5.1 General charge conditions . 12
5.2 Capacity . 13
5.3 SOC adjustment . 13
6 Reliability and abuse tests . 13
6.1 General . 13
6.2 Mechanical test . 14
6.2.1 Vibration . 14
6.2.2 Mechanical shock . 15
6.2.3 Crush . 16
6.3 Thermal test. 17
6.3.1 High temperature endurance . 17
6.3.2 Temperature cycling . 18
6.4 Electrical test . 18
6.4.1 External short circuit . 18
6.4.2 Overcharge . 19
6.4.3 Forced discharge . 19
7 Description of test results . 20
Annex A (informative) Selective test conditions . 21
Bibliography . 22

Figure 1 – Example of temperature measurement of cell . 12
Figure 2 – PSD of acceleration plotted against frequency . 15
Figure 3 – Examples of crush test . 17

Table 1 – Discharge conditions . 13
Table 2 – Values for PSD and frequency . 15
Table 3 – Mechanical shock test - parameters . 16
Table 4 – Temperatures and time duration for temperature cycling . 18
IEC CDV 62660-2 © IEC 2026
Table 5 – Test result description . 20
Table A.1 – Capacity test conditions . 21

IEC CDV 62660-2 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Secondary lithium-ion cells for the propulsion of electric road vehicles -
Part 2: Reliability and abuse testing

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for
standardization comprising all national electrotechnical committees (IEC National Committees).
The object of IEC is to promote international co-operation on all questions concerning
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced
publications is indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve
the use of (a) patent(s). IEC takes no position concerning the evidence, validity or applicability
of any claimed patent rights in respect thereof. As of the date of publication of this document,
IEC [had/had not] received notice of (a) patent(s), which may be required to implement this
document. However, implementers are cautioned that this may not represent the latest
IEC CDV 62660-2 © IEC 2026
information, which may be obtained from the patent database available at https://patents.iec.ch.
IEC shall not be held responsible for identifying any or all such patent rights.
IEC 62660-2 has been prepared by IEC technical committee 21: Secondary cells and batteries.
It is an International Standard.
This third edition cancels and replaces the second edition published in 2018. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) The procedure of forced discharge test has been clarified (6.4.3.2).
b) "Cell block" has been added to the scope (Clause 1).
c) Option of temperature cycling test with electrical operation has been deleted ( 6.3.2).
d) The test conditions for overcharge test have been revised (6.4.2.2).
The text of this International Standard is based on the following documents:
Draft Report on voting
21/XX/FDIS 21/XX/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all the parts in the IEC 62660 series, published under the general title Secondary
lithium-ion cells for the propulsion of electric road vehicles, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC CDV 62660-2 © IEC 2026
INTRODUCTION
The commercialization of electric road vehicles including battery, hybrid and plug -in hybrid
electric vehicles has been accelerated in the global market, responding to the global concerns
on CO reduction and energy security. This, in turn, has led to rapidly increasing demand for
high-power and high-energy-density traction batteries. Lithium-ion batteries are estimated to be
one of the most promising secondary batteries for the propulsion of electric vehicles. In the light
of the rapid spread of hybrid electric vehicles and the emergence of battery and plug -in hybrid
electric vehicles, a standard method for testing reliability and abuse requirements of lithium -ion
batteries is indispensable for securing a basic level of safety and obtaining essential data for
the design of vehicle systems and battery packs.
This document specifies reliability and abuse testing for automobile traction lithium -ion cells
that basically differ from the other cells including those for portable and stationary applications
specified by other IEC standards. For automobile application, it is important to note the usage
specificity; i.e. the design diversity of automobile battery packs and systems, and specific
requirements for cells and batteries corresponding to each of such designs. Based on these
facts, the purpose of this document is to provide a basic test methodology with general
versatility, which serves a function in common primary testing of lithium-ion cells to be used in
a variety of battery systems. This document does not provide any pass-fail criteria for the tests,
but specifies a standard classification of descriptions for test results.
This document is associated with ISO 12405-4:2018 [1].
IEC 62660-1:2018 [2] specifies the performance testing of lithium-ion cells for electric vehicle
application.
IEC 62660-3:2022 [3] specifies the safety requirements of lithium-ion cells for electric vehicle
application.
IEC CDV 62660-2 © IEC 2026
1 Scope
This part of IEC 62660 specifies test procedures to observe the reliability and abuse behaviour
of secondary lithium-ion cells and cell blocks used for propulsion of electric vehicles including
battery electric vehicles (BEV) and hybrid electric vehicles (HEV).
This document specifies the standard test procedures and conditions for basic characteristics
of lithium-ion cells for use in propulsion of battery and hybrid electric vehicles. The tests are
indispensable for obtaining essential data on reliability and abuse behaviour of lithium-ion cells
for use in various designs of battery systems and battery packs.
This document provides standard classification of description of test results to be used for the
design of battery systems or battery packs.
NOTE The safety requirements of lithium-ion cells for electric vehicle application are defined in IEC 62660-3:2022
[3].
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60068-2-64:2008, Environmental testing - Part 2-64: Tests - Test Fh: Vibration, broadband
random and guidance
ISO/TR 8713:2019, Electrically propelled road vehicles — Vocabulary
ISO 16750-3:2023, Road vehicles — Environmental conditions and testing for electrical and
electronic equipment — Part 3: Mechanical loads
ISO 16750-4:2023, Road vehicles — Environmental conditions and testing for electrical and
electronic equipment — Part 4: Climatic loads
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TR 8713:2019 and
the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
– IEC Electropedia: available at http://www.electropedia.org/
– ISO Online browsing platform: available at http://www.iso.org/obp
3.1
battery electric vehicle
BEV
electric vehicle with only a traction battery as power source for vehicle propulsion
3.2
cell block
group of cells connected together in parallel configuration with or without protective devices,
e.g. fuse or positive temperature coefficient resistor (PTC), not yet fitted with its final housing,
terminal arrangement and electronic control device
IEC CDV 62660-2 © IEC 2026
3.3
hybrid electric vehicle
HEV
vehicle with both a rechargeable energy storage system and a fuelled power source for
propulsion
3.4
rated capacity
C
n
capacity value of a cell in ampere hours (Ah) determined under specified conditions and
declared by the cell manufacturer
Note 1 to entry: n in C is the time base in hours (h). In this document, n = 3 for BEV application and n = 1 for HEV
n
application unless otherwise specified.
3.5
I
t
reference test current in amperes (A) which is expressed as 𝐼 =𝐶 /1
t 𝑛
Note 1 to entry: 1 has a dimension of time in hours (h).
Note 2 to entry: See IEC 61434:1996 [4], Clause 2.
3.6
room temperature
temperature o
...