IEC 61960-4:2024

IEC 61960-4 ®
Edition 2.0 2024-07
COMMENTED VERSION
INTERNATIONAL
STANDARD
colour
inside
Secondary cells and batteries containing alkaline or other non-acid
electrolytes – Secondary lithium cells and batteries for portable applications –
Part 4: Coin secondary lithium cells, and batteries made from them
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IEC 61960-4 ®
Edition 2.0 2024-07
COMMENTED VERSION
INTERNATIONAL
STANDARD
colour
inside
Secondary cells and batteries containing alkaline or other non-acid
electrolytes – Secondary lithium cells and batteries for portable applications –
Part 4: Coin secondary lithium cells, and batteries made from them
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.220.99 ISBN 978-2-8322-9503-8
– 2 – IEC 61960-4:2024 CMV © IEC 2024
CONTENTS
FOREWORD .4
1 Scope .6
2 Normative references .6
3 Terms and definitions .7
4 Parameter measurement tolerances .8
5 Cell designation and marking.8
5.1 Cell designation .8
5.2 Marking . 10
5.2.1 General . 10
5.2.2 Small Swallowable cells or batteries . 11
6 Electrical tests . 11
6.1 General . 11
6.2 Charging procedure for test purposes . 12
6.3 Discharge performance . 13
6.4 Charge (capacity) recovery after long-term storage . 14
6.5 Endurance in cycles . 14
6.6 Cell or battery internal resistance (AC resistance) . 15
6.6.1 General . 15
6.6.2 Test – General . 15
6.6.3 Measurement . 15
6.6.4 Acceptance criterion . 16
7 Differentiation . 16
Annex A (normative) Requirements for secondary lithium watch batteries . 17
A.1 General . 17
A.2 Physical requirements. 17
A.2.1 Symbols and shape of cell . 17
A.2.2 Dimensions and size codes . 17
A.3 Test methods for determining the resistance to leakage . 18
A.3.1 Preconditioning and initial visual examination . 18
A.3.2 High temperature and humidity test . 18
A.3.3 Test by temperature cycle . 19
A.4 Visual examination and acceptance criteria . 19
A.4.1 Preconditioning . 19
A.4.2 Magnification . 19
A.4.3 Leakage levels and classification . 19
A.4.4 Acceptance conditions . 20
Annex B (informative) Guidelines for designers of equipment using lithium batteries . 21
Bibliography . 22
List of comments . 23

Figure 1 – Dimensional characteristics .9
Figure 2 – Sample sizes and sequence of tests . 12
Figure A.1 – Dimensional drawing. 17
Figure A.2 – Test by temperature cycles . 19

Table 1 – Electrochemical systems in current practical use .9
Table 2 – Examples of recommended generally used upper limit charge voltage . 13
Table 3 – Recommended end-of-discharge voltage limit Example of generally used
lower limit of end-of-discharge voltage . 14
Table 4 – Minimum number of cycles . 15
Table A.1 – Dimensions and size codes for watch batteries . 18
Table A.2 – Storage conditions . 18
Table B.1 – Equipment design guidelines . 21

– 4 – IEC 61960-4:2024 CMV © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SECONDARY CELLS AND BATTERIES CONTAINING ALKALINE OR
OTHER NON-ACID ELECTROLYTES – SECONDARY LITHIUM CELLS
AND BATTERIES FOR PORTABLE APPLICATIONS –

Part 4: Coin secondary lithium cells, and batteries made from them

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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shall not be held responsible for identifying any or all such patent rights.
This commented version (CMV) of the official standard IEC 61960-4:2024 edition 2.0
allows the user to identify the changes made to the previous IEC 61960-4:2020
edition 1.0. Furthermore, comments from IEC SC 21A experts are provided to explain the
reasons of the most relevant changes, or to clarify any part of the content.
A vertical bar appears in the margin wherever a change has been made. Additions are in
green text, deletions are in strikethrough red text. Experts' comments are identified by a
blue-background number. Mouse over a number to display a pop-up note with the
comment.
This publication contains the CMV and the official standard. The full list of comments is
available at the end of the CMV.

IEC 61960-4 has been prepared by subcommittee 21A: Secondary cells and batteries
containing alkaline or other non-acid electrolytes, of IEC technical committee 21: Secondary
cells and batteries, in cooperation with ISO technical committee 114: Horology. It is an
International Standard.
This second edition cancels and replaces the first edition published in 2020. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) added an annex to standardize requirements for secondary lithium watch batteries;
b) added new chemistries;
c) added a table to standardize dimensions and size codes for secondary lithium watch
batteries;
d) modified marking requirements.
The text of this International Standard is based on the following documents:
Draft Report on voting
21A/880/FDIS 21A/892/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 parts in the IEC 61960 series, published under the general title Secondary cells and
batteries containing alkaline or other non-acid electrolytes – Secondary lithium cells and
batteries for portable applications, 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.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 61960-4:2024 CMV © IEC 2024
SECONDARY CELLS AND BATTERIES CONTAINING ALKALINE OR
OTHER NON-ACID ELECTROLYTES – SECONDARY LITHIUM CELLS
AND BATTERIES FOR PORTABLE APPLICATIONS –

Part 4: Coin secondary lithium cells, and batteries made from them

1 Scope
This part of IEC 61960 specifies performance tests, designations, markings, dimensions and
other requirements for coin secondary lithium cells and batteries for portable applications,
watches, and backup power supply such as memory backup applications. In particular,
watch-specific requirements are specified in Annex A. 1
This document provides purchasers and users of coin secondary lithium cells and batteries with
a set of criteria with which they can assess the performance of coin secondary lithium cells and
batteries offered by various manufacturers.
This document defines a minimum required level of performance and a standardized
methodology by which testing is performed and the results of this testing are reported to the
user. Hence, users will be able to establish the viability of commercially available cells and
batteries via the declared specification and thus be able to select the cell or battery best suited
for their intended application.
This document covers coin secondary lithium cells and batteries with a range of chemistries.
Each electrochemical couple has a characteristic voltage range over which, during discharge,
it releases its electrical capacity, a characteristic nominal voltage and a characteristic
end-of-discharge voltage. Users of coin secondary lithium cells and batteries are requested to
consult the manufacturer for advice.
This document also provides guidelines for designers of equipment using lithium batteries (see
Annex B).
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 60050-482:2004, International Electrotechnical Vocabulary (IEV) – Part 482: Primary and
secondary cells and batteries
IEC 60086-4:2019, Primary batteries – Part 4: Safety of lithium batteries
IEC 62133-2:2017, Secondary cells and batteries containing alkaline or other non-acid
electrolytes – Safety requirements for portable sealed secondary cells, and for batteries made
from them, for use in portable applications – Part 2: Lithium systems
IEC 62133-2:2017/AMD1:2021
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-482 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1 2
coin cell
coin battery
lithium button cell
lithium button battery
small round cell or battery where the overall height is less than the diameter, containing
non-aqueous electrolyte
[SOURCE: IEC 60086-4:2019, 3.3, modified – Note to entry omitted.]
3.2
secondary lithium cell
secondary cell whose electrical energy is derived from oxidation and the reduction of lithium
Note 1 to entry: This cell is not ready for use in an application because it is not yet fitted with its final housing,
terminal arrangement and electronic control device.
3.3
secondary lithium battery
unit which incorporates one or more secondary lithium cells and which is ready for use
Note 1 to entry: This unit incorporates adequate housing and a terminal arrangement and may have electronic
control devices.
3.4
nominal voltage
suitable approximate value of voltage used to designate or identify a cell, or a battery
Note 1 to entry: The nominal voltages of coin secondary lithium cells are shown in Table 1.
[SOURCE: IEC 60050-482:2004, 482-03-31, modified – "electrochemical system" has been
omitted from the definition and the note has been added.]
3.5
rated capacity
quantity of electricity mAh (milliampere-hours) that a single cell or battery can deliver, when
charged, stored and discharged under specified conditions and declared by the manufacturer
3.6
end-of-charge voltage
voltage attained at the end of a charging step, at a specified constant current or a specified
constant resistance
Note 1 to entry: The end-of-charge voltage may be used to initiate the termination of the charge process.
[SOURCE: IEC 60050-482:2004, 482-05-55, modified – "or a specified constant resistance" has
been added to the definition.]

– 8 – IEC 61960-4:2024 CMV © IEC 2024
3.7
end-of-discharge voltage
specified closed circuit voltage at which a discharge of a cell or battery is terminated
[SOURCE: IEC 60050-482:2004, 482-03-30, modified – The synonyms "final voltage", "cut-off
voltage", and "end-point voltage" have been omitted and the words "closed circuit" and "cell"
have been added to the definition.]
3.8
charge recovery
capacity recovery
capacity that a cell or battery can deliver with subsequent recharge, after storage at a specific
temperature, for a specific time, as a percentage of the rated capacity
4 Parameter measurement tolerances
The overall accuracy of controlled or measured values, relative to the specified or actual values,
shall be within the following tolerances:
a) ±1 % for voltage;
b) ±1 % for current;
c) ±1 % for capacity;
d) ±2 °C for temperature;
e) ±0,1 % for time;
f) ±0,1 mm for dimensions.
These tolerances comprise the combined accuracy of the measuring instruments, the
measurement techniques used, and all other sources of error in the test procedure.
The details of the instrumentation used shall be provided in any report of results.
5 Cell designation and marking
5.1 Cell designation
Cells shall be designated with the following form:
A A DDHH
1 2
where
A designates the positive electrode system in which:
C or U is lithium cobalt oxide;
FP is lithium iron phosphate;
M is lithium manganese oxide;
N is lithium nickel oxide;
NB is niobium oxide;
V is vanadium oxide;
T is lithium titanium oxide.
A designates the negative electrode system in which:
C is carbon;
L is lithium aluminium alloy;
S is lithium silicon oxide/alloy;
T or TL is lithium titanium oxide;
DD designates the diameter in mm;
HH designates the height in 1/10 of mm.
The requirements concerning code letters on electrochemical systems are given in Table 1.
Table 1 – Electrochemical systems in current practical use
Nominal
Positive electrode Electrolyte Negative electrode Code letters
voltage
(V)
Lithium transition metal
3,7 3,6
a
(cobalt, manganese, Carbon
UC or MC or NC 3
to 3,9
nickel) oxide
Lithium iron phosphate Carbon 3,2
FPC 4
3,0 2,4
Lithium cobalt oxide Lithium titanium oxide UT
Vanadium oxide Lithium aluminium alloy 3,0 VL
Lithium manganese
Lithium aluminium alloy 3,0 ML
oxide
Non-aqueous
solution with
Lithium manganese
Lithium silicon oxide/alloy 3,0 MS
lithium salt
oxide
Lithium cobalt oxide Lithium titanium oxide 2,3 CTL
Niobium oxide Lithium aluminium alloy 2,0 NBL
Lithium manganese
Lithium titanium oxide 1,5 MT
oxide
Lithium titanium oxide Lithium-carbon compound 1,5 TC
Lithium titanium oxide Lithium aluminium alloy 1,5 TL
Lithium titanium oxide Lithium silicon oxide 1,5 TS
The above code letters are given as examples. Each positive electrode and negative electrode shall be designated
with one or two letters. Any code letter can be decided on by agreement between the manufacturer and user when
there is a same chemistry which has different nominal voltages.
a
For lithium transition metal oxide positive electrodes, the symbols for the highest element composition of cobalt,
manganese or nickel shall be used. (For example, the symbol for a lithium transition metal oxide with a
composition of LiNi Mn Co O is N.) 6
0,6 0,2 0,2 2
Key
h overall height of the cell
d diameter of the cell
Figure 1 – Dimensional characteristics

– 10 – IEC 61960-4:2024 CMV © IEC 2024
Coin secondary lithium cells complying with this document shall be designated by the following
system consisting of code letters and numbers. For the electrochemical systems, the code
letters shall be expressed using two letters (a maximum of three letters), followed by diameter
and height expressed in that order. See Figure 1.
EXAMPLE                                   ML 1220

Electrochemical systems code letters
Dimensions: d in millimetres
Dimensions: h in 1/10 of millimetres

NOTE Notwithstanding the above specification, other designations can be used according to an
agreement between manufacturer and user.
5.2 Marking
5.2.1 General
With the exception of small swallowable cells or batteries (see 5.2.2), each cell or battery of the
following pieces of information shall be marked with the following information (details on the
location of the marking are given after the following list):
a) cell designation, IEC or common designation;
b) the year and month or week of manufacture (may be given in code);
c) polarity of the positive (+) terminal;
d) nominal voltage;
e) rated capacity;
f) name or trademark of the manufacturer or supplier;
g) cautionary advice;
g) caution for ingestion of swallowable cells and batteries (see IEC 60086-4);
h) combination of "secondary (rechargeable)" and "Li", or "secondary (rechargeable)" and
"Li-ion".
The designation a) and the polarity c) shall be marked on the cell or battery.
For cells or batteries with an internal AC resistance less than or equal to 3 Ω, intended to be
user replaceable or not contained in the equipment, the additional marking of h) shall be marked
on the cell or battery.
Other information shall be either marked on the cell or battery, provided in the specification
sheet or instruction manual, or marked on the immediate package.

5.2.2 Small Swallowable cells or batteries
For cells or batteries that fit entirely within the ingestion gauge (Figure 3 in IEC 62133-2:2017),
the designation specified in 5.2.1 a) and the polarity specified in 5.2.1 c) shall be marked on
the cell or battery.
For cells or batteries that have a diameter of 16 mm or more intended to be user replaceable
or not contained in the equipment, the safety sign KEEP OUT OF REACH OF CHILDREN shall
be marked on the cell or battery in accordance with Annex F of IEC 60086-4:2019. 7
For cells or batteries with an internal AC resistance less than or equal to 3 Ω, intended to be
user replaceable or not contained in the equipment, the additional marking of 5.2.1 h) shall be
marked on the cell or battery.
All other information shown in 5.2.1 and caution for ingestion of swallowable cells and batteries
(see IEC 62133-2:2017, 9.3) should be given in the specification sheet, or in the instruction
manual or on the immediate package instead of on the cell or battery.
6 Electrical tests
6.1 General
Only cell or battery samples which are less than two months (60 days) old from the date of
manufacture shall be used for the tests specified in this document.
Unless otherwise stated in this document, the following tests shall be carried out in an ambient
temperature of 20 °C ± 5 °C.
Tested cells or batteries should not exceed the upper limit charge voltage or end-of-discharge
voltage limit during the test.
Coin secondary lithium cells or batteries have different characteristics and features in terms of
voltage, discharge performance, capacity recovery after storage, and cycling depending on their
chemistries. Therefore, conditions specified by the manufacturer shall be used in order to make
the most of cell or battery characteristics.
The sample sizes and the sequence of the tests are described in Figure 2.

– 12 – IEC 61960-4:2024 CMV © IEC 2024

Figure 2 – Sample sizes and sequence of tests
6.2 Charging procedure for test purposes
There are two different charging methods for the coin secondary lithium cells or batteries:
constant voltage charge and constant current charge. The charge method and conditions
specified by the manufacturer shall be used. When such information is not available, the charge
voltage shall be in accordance with Table 2. The charge voltages in Table 2 are generally used
upper limits, and some manufacturers allow higher values. Contact each manufacturer for
details.
Table 2 – Examples of recommended generally used upper limit charge voltage
Recommended Generally
Code letters used upper limit
charge voltage
UC or MC or NC 4,25 V
FPC 3,6 V
UT 3,2 V
VL 3,55 V
ML 3,2 V
MS 3,3 V
CTL 2,7 V
NBL 2,5 V
MT 2,6 V
TC 3,15 V
TL 1,7 V
TS 3,0 V
6.3 Discharge performance
This test verifies the rated capacity of a cell or battery at 20 °C.
Step 1: The cell or battery shall be charged in accordance with 6.2.
Step 2: The cell or battery shall be stored in an ambient temperature of 20 °C ± 5 °C, for not
less than 1 h and not more than 4 h.
Step 3: The cell or battery shall be discharged, in an ambient temperature of 20 °C ± 5 °C, at a
constant current or constant resistance to the end-of-discharge voltage specified by the
manufacturer. When such information is not available, the recommended end-of-discharge
voltage limits are shown in Table 3. The discharge method and condition specified by the
manufacturer shall be used. The end-of-discharge voltages in Table 3 are generally lower limits,
and some manufacturers allow lower values. Contact each manufacturer for details.
Step 4: The capacity (mAh) delivered during step 3 shall be not less than the rated capacity
declared by the manufacturer.
– 14 – IEC 61960-4:2024 CMV © IEC 2024
Table 3 – Recommended end-of-discharge voltage limit Example of generally used
lower limit of end-of-discharge voltage
Recommended end-of-
discharge voltage limit
Code letters
Generally used lower limit of
end-of-discharge voltage
UC or MC or NC 2,5 V
FPC 2,5 V
UT 2,0 V
VL 2,5 V
ML 2,0 V
MS 2,0 V
CTL 2,0 V
NBL 1,0 V
MT 1,0 V
TC 0,5 V
TL 0,8 V
TS 1,0 V
6.4 Charge (capacity) recovery after long-term storage
This test verifies the capacity of a cell or battery after extended storage at 100 % state of charge,
followed by a subsequent charge.
Step 1: The cell or battery shall be charged in accordance with the specific conditions specified
by the manufacturer.
Step 2: The cell or battery shall be stored at 60 °C for 20 days.
Step 3: The cell or battery shall be stored, in an ambient temperature of 20 °C ± 5 °C, for not
less than 1 h and not more than 4 h.
Step 4: The cell or battery shall be charged, in an ambient temperature of 20 °C ± 5 °C, using
the method declared by the manufacturer. 8
Step 5: The cell or battery shall be discharged in an ambient temperature of 20 °C ± 5 °C, at
the discharge conditions specified by the manufacturer, until its voltage is equal to the
manufacturer's specified end-of-discharge voltage. The cell or battery shall be charged before
discharge by the specific condition by the manufacturer.
Step 6: The capacity (mAh) delivered during step 5 shall be more than 50 % of its rated capacity.
6.5 Endurance in cycles
This test verifies the ability of the charge-discharge cycle.
Step 1: The cell or battery shall be discharged, in an ambient temperature of 20 °C ± 5 °C, using
the method declared by the manufacturer.
Step 2: The cell or battery shall be continuously charged and discharged, in an ambient
temperature of 20 °C ± 5 °C.
The cell or battery shall be charged until its voltage is equal to the specified end-of-charge
voltage, or it shall be charged for the specified amount of time after its voltage is equal to the
specified end-of-charge voltage, using the method and conditions declared by the manufacturer.
The cell or battery shall be discharged in an ambient temperature of 20 °C ± 5 °C, until its
voltage is equal to the specified end-of-discharge voltage, or it shall be discharged for the
specified amount of time, using the method declared by the manufacturer.
The test shall be terminated when the discharge capacity reaches 50 % of its first cycle. The
result shall satisfy the minimum number of cycles in Table 4.
Table 4 – Minimum number of cycles
Code letters Minimum number of cycles
UC or MC or NC 100
FPC 100
UT 100
VL 5
ML 5
MS 50
CTL 100
NBL 5
MT 100
TC 100
TL 5
TS 50
The test procedure in 6.5 is a representative and unified accelerated method to cover
various electrochemical systems, and actual charge-discharge conditions may be
different depending on each application. The above minimum numbers of cycles are
values tested according to the procedure in 6.5. This accelerated test method might
can result in a fewer number of cycles than in actual use.

6.6 Cell or battery internal resistance (AC resistance)
6.6.1 General
Internal AC resistance measurement is necessary to evaluate cell performance. When internal
AC resistance is smaller than 3 Ω, the safety standard of IEC 62133-2:2017, Annex D is
applicable. Cells with internal AC resistance less than or equal to 3 Ω shall be tested in
accordance with Table 1 of IEC 62133-2:2017.
6.6.2 Test – General
This test verifies the internal resistance of a secondary lithium cell or battery by the alternating
current (AC) method.
The internal resistance shall be measured at conditions (e.g. voltage, temperature) specified
by the manufacturer.
6.6.3 Measurement
The alternating RMS voltage, U , shall be measured while applying an alternating RMS current,
a
I , at the frequency of 1,0 kHz ± 0,1 kHz, to the cell or battery, for a period of 1 s to 5 s.
a
– 16 – IEC 61960-4:2024 CMV © IEC 2024
All voltage measurements shall be made at the terminals of the cell or battery independently of
the contacts used to carry current.
The internal AC resistance, R , is given by:
ac
U
a
R = Ω
( )
ac
I
a
U
a
R =
ac
I
a
where
U is the alternating RMS voltage in V;
a
I is the alternating RMS current in A.
a
The alternating current should be selected so that the peak voltage stays below 20 mV.
NOTE This method will in fact measure the impedance which, at the frequency specified, is approximately equal to
the resistance.
6.6.4 Acceptance criterion
The internal AC resistance of the cell or battery shall be not greater than the value of R ,
ac
declared by the manufacturer.
7 Differentiation
Technical consideration shall be taken to prevent coin secondary lithium cells and batteries
from being confused with primary lithium cells and batteries which are similar in appearance
and size. (For example, construction of an attached terminal in such a way that the terminal
cannot be replaced, affixing a note of caution, etc.) Attention shall be paid to the designation
because the voltage is also different between the secondary batteries.
The required information shall be marked on coin secondary lithium cells or batteries in
accordance with 5.2.
Annex A
(normative)
Requirements for secondary lithium watch batteries
A.1 General
This annex specifies dimensions, test methods and requirements for secondary lithium batteries
for watches.
A.2 Physical requirements
A.2.1 Symbols and shape of cell
The symbols used to denote the various dimensions in Figure A.1 are as follows.

Key
h overall height of the cell
h height of the side
d diameter of the cell
d diameter of the negative contact
Figure A.1 – Dimensional drawing
Except for cells with terminals, the shape of cells shall meet the following requirements: 9
• The height of the side is greater than or equal to two thirds of the overall height of the cell.
• The height of the side is smaller than the overall height minus 0,02 mm.
• The negative contact is the highest point of the battery.
• The diameter of the negative contact is greater than or equal to a half of the diameter of the
cell.
A.2.2 Dimensions and size codes
Dimensions and size codes of secondary lithium watch batteries shall be in accordance with
Figure A.1 and Table A.1.
None of the tolerances of Table A.1 shall be exceeded during the charge and discharge
conditions in accordance with 6.2, 6.3 and 6.5.

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For batteries placed on the market prior to and within 2 years from the publication date of this
second edition of IEC 61960-4, other dimensions and size codes may be used according to the
agreement between the manufacturer and the user. 10
Table A.1 – Dimensions and size codes for watch batteries 11
Dimensions in millimetres
Height h
Diameter
Code
16 20 21 27 30 32 37
d
Code Tolerance
Tolerance
+0,15 +0,20 +0,20 +0,20 +0,20 +0,20 +0,20
−0,20 −0,20 −0,20 −0,20 −0,20 −0,20 −0,20
4 4,8
1,60
−0,15
5 5,8 1,60
−0,15
6 6,8 1,60 2,10
−0,15
9 9,5 2,00 2,70 3,70
−0,15
16 16 1,60 2,00
−0,25
20 20 1,60 2,00 3,20
−0,25
24 24,5 3,00
−0,25
30 30 3,20
−0,25
A.3 Test methods for determining the resistance to leakage 12
A.3.1 Preconditioning and initial visual examination
Before carrying out the tests specified in A.3.2 and A.3.3, the batteries shall be submitted to a
visual examination according to the requirements stated in Clause A.4.
For tests in A.3.2, batteries shall be pre-stored at the specified temperature (45 °C) for 2 h.
Batteries shall be moved from the preconditioning (alternative pre-stored) chamber (or oven)
into the high temperature and humidity test chamber within minutes in order to avoid cooling of
the battery and the risk of condensation at elevated humidity.
A.3.2 High temperature and humidity test
The cell or battery shall be charged according to the charging method and conditions specified
by the manufacturer (see 6.2). The battery shall be stored under the conditions specified in
Table A.2.
Table A.2 – Storage conditions
Temperature Relative humidity
°C %
45 ± 2 90 to 95
The storage duration should be agreed between the manufacturer and the user.
The temperature tolerance of ±2 °C is for the temperature maintenance period and a brief
overshoot in temperature is allowed during the transition period.
A.3.3 Test by temperature cycle
The cell or battery shall be charged according to the charging method and conditions specified
by the manufacturer (see 6.2). The battery shall be submitted to temperature cycles according
to the schedule in Figure A.2. The number of cycles should be agreed between the manufacturer
and the user.
The temperature tolerance of ±2 °C is for the temperature maintenance period and a brief
overshoot in temperature is allowed during the transition period.

Figure A.2 – Test by temperature cycles
A.4 Visual examination and acceptance criteria
A.4.1 Preconditioning
Before carrying out the initial visual examination or after the tests specified in A.3.2 and A.3.3,
the batteries shall be stored for at least 24 h at room temperature and at a relative humidity of
55 % ± 20 %.
The leakage should be observed after crystallisation of the electrolyte. The time of the storage
of 24 h may be prolonged if necessary. This examination may be applied to new or used
batteries, or to batteries which have been submitted to different tests.
A.4.2 Magnification
The visual examination shall be carried out at a magnification of x15.
A.4.3 Leakage levels and classification
The visual examination shall be carried out under a diffuse white light of 900 lx to 1 100 lx at
the surface of the battery to be inspected (see IEC 60086-3:2021, Table 10). 13

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A.4.4 Acceptance conditions
The acceptable levels of leakage, as well as the proportion of defective pieces, shall be agreed
between the manufacturer and the user.

Annex AAnnex B
(informative)
Guidelines for designers of equipment using lithium batteries
Equipment design guidelines are given in Table B.1.
Table B.1 – Equipment design guidelines
Possible consequences if the
Item Sub-item Recommendations recommendations are not
observed
(1) Battery holder and battery a) Battery compartments should Unless protection is provided
compartment be designed so that if a battery against battery reversal, damage
is reversed, open circuit is to equipment can occur from
achieved. Battery resultant electrolyte leakage,
compartments should be overheating, rupture, explosion or
clearly and permanently fire
marked to show the correct
orientation of batteries
b) Battery compartments should Equipment might can be damaged
be designed so that batteries or might can not operate
of sizes other than those
specified cannot be inserted
and make contact
c) Battery compartments should an
Battery compartments might c
be designed to allow generated be damaged when internal
gases to escape pressure of the battery becomes
too high due to gas generation
d) Battery compartments should
be designed to be waterproof
e) Battery compartments should
be designed to be explosion-
proof when tightly sealed
f) Battery compartments should Battery might can be deformed
be isolated from heat and leak electrolyte due to
generated by the equipment excessive heat
g) Battery compartments should Children might can remove
be designed so that they batteries from the compartment
cannot easily be opened by and swallow them
children
(2) Contacts and terminals a) Material and shape of contacts Heat might generate can be
and terminals should be generated at the contact due to
insufficient connection
selected so that effective
electric contact is maintained
b) Auxiliary circuit should be Equipment might can be damaged
designed to prevent reverse or might can not operate
installation of batteries
c) Contacts and terminals should Equipment might can be
be designed to prevent reverse damaged. Battery might can
installation of batteries cause electrolyte leakage,
overheating, rupture, explosion or
fire
d) Direct soldering or welding to a Battery might can leak, overheat,
battery should be avoided rupture, explode or catch fire

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Bibliography
IEC 60051 (all parts), Direct acting indicating analogue electrical measuring instruments and
their accessories
IEC 60086-1, Primary batteries – Part 1: General
IEC 60086-2, Primary batteries – Part 2: Physical and electrical specifications
IEC 60086-3:2021, Primary batteries – Part 3: Watch batteries
IEC 60086-4:2019, Primary batteries – Part 4: Safety of lithium batteries
IEC 60485, Digital electronic d.c. voltmeters and d.c. electronic analogue-to-digital converters
IEC 61434, Secondary cells and batteries containing alkaline or other non-ac
...