IEC 61951-2:2011

Secondary cells and batteries containing alkaline or other non-acid electrolytes - Portable sealed rechargeable single cells - Part 2: Nickel-metal hydride

IEC 61951-2:2011 specifies marking, designation, dimensions, tests and requirements for portable sealed nickel-metal hydride, small prismatic, cylindrical and button rechargeable single cells, suitable for use in any orientation. This third edition cancels and replaces the second edition published in 2003 of which it constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- clause 4: addition of 2 parameters;
- clause 5: addition of cells type "S" and cells type "T";
- subclause 6.1.2: addition of new cylindrical cells;
- subclause 7.8: addition of a specific test for "S" cells.

Accumulateurs alcalins et autres accumulateurs à électrolyte non acide - Accumulateurs individuels portables étanches - Partie 2: Nickel-métal hydrure

La CEI 61951-2:2011 spécifie le marquage, la désignation, les dimensions, les essais et les exigences applicables aux petits éléments parallélépipédiques, aux éléments cylindriques et aux éléments boutons, individuels, portables, rechargeables, étanches, au nickel-métal hydrure, pouvant être utilisés dans toutes les orientations. Cette troisième édition annule et remplace la deuxième édition parue en 2003, dont elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- article 4: ajout de 2 paramètres;
- article 5: ajout d'éléments type "S" et éléments type "T";
- paragraphe 6.1.2: ajout de nouveaux éléments cylindriques;
- paragraphe 7.8: ajout d'un essai spécifique pour les éléments "S".

General Information

• Status: Published
• Publication Date: 24-May-2011
• ICS: 29.220.30 - Alkaline secondary cells and batteries
• Technical Committee: SC 21A - Secondary cells and batteries containing alkaline or other non-acid electrolytes
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 22-Mar-2017

Relations

• Revised: IEC 61951-2:2017 - Secondary cells and batteries containing alkaline or other non acid electrolytes - Secondary sealed cells and batteries for portable applications - Part 2: Nickel-metal hydride
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61951-2
®

Edition 3.0 2011-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Secondary cells and batteries containing alkaline or other non-acid
electrolytes – Portable sealed rechargeable single cells –
Part 2: Nickel-metal hydride

Accumulateurs alcalins et autres accumulateurs à électrolyte non acide –
Accumulateurs individuels portables étanches –
Partie 2: Nickel-métal hydrure


IEC 61951-2:2011

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2011 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.


Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: www.iec.ch

About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
 Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
 IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
 Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
 Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]


A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
 Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
 Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
 Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
 Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: [e-mail]
Tél.: [phone]
Fax: [phone]

---------------------- Page: 2 ----------------------
IEC 61951-2
®

Edition 3.0 2011-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Secondary cells and batteries containing alkaline or other non-acid
electrolytes – Portable sealed rechargeable single cells –
Part 2: Nickel-metal hydride

Accumulateurs alcalins et autres accumulateurs à électrolyte non acide –
Accumulateurs individuels portables étanches –
Partie 2: Nickel-métal hydrure

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX V
ICS 29.220.30 ISBN 978-2-88912-497-8

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – 61951-2 © IEC:2011
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Parameter measurement tolerances . 7
5 Cell designation and marking. 8
5.1 Cell designation . 8
5.1.1 Small prismatic cells and cylindrical cells . 8
5.1.2 Button cells . 9
5.2 Cell termination . 9
5.3 Marking . 9
5.3.1 Small prismatic cells and cylindrical cells . 9
5.3.2 Button cells . 10
6 Dimensions . 10
6.1 Small prismatic cells and cylindrical cells . 10
6.1.1 General . 10
6.1.2 Small prismatic cells . 11
6.1.3 Cylindrical cells . 12
6.2 Button cells . 14
7 Electrical tests . 14
7.1 General . 14
7.2 Charging procedure for test purposes . 14
7.3 Discharge performance . 15
7.3.1 General . 15
7.3.2 Discharge performance at 20 °C . 15
7.3.3 Discharge performance at 0 °C . 15
7.3.4 Discharge performance for rapid charge cells (R cells) . 16
7.4 Charge (capacity) retention . 16
7.5 Endurance . 17
7.5.1 Endurance in cycles . 17
7.5.2 Permanent charge endurance . 19
7.6 Charge acceptance at constant voltage . 23
7.7 Overcharge . 23
7.7.1 Small prismatic, L, M, H, X, LS or MS cylindrical, and button cells . 23
7.7.2 LT/LU, MT/MU or HT/HU cylindrical cells . 23
7.7.3 R cylindrical cells. 23
7.8 Safety device operation . 24
7.9 Surface temperature limitation device operation (for S cell only) . 24
7.10 Storage . 25
7.11 Charge acceptance at +55 °C for LT, MT or HT cylindrical cells . 25
7.12 Internal resistance . 26
7.12.1 General . 26
7.12.2 Measurement of the internal a.c. resistance . 26
7.12.3 Measurement of the internal d.c. resistance . 27
8 Mechanical tests. 27

---------------------- Page: 4 ----------------------
61951-2 © IEC:2011 – 3 –
9 Safety requirements . 27
10 Type approval and batch acceptance. 27
10.1 Type approval . 27
10.1.1 Type approval for small prismatic cells and button cells . 27
10.1.2 Type approval for cylindrical cells . 28
10.2 Batch acceptance . 29
Bibliography . 31

Figure 1 – Jacketed cylindrical cells . 11
Figure 2 – Jacketed small prismatic cells . 11
Figure 3 – Jacketed cells dimensionally interchangeable with primary cells . 12
Figure 4 – Button cells . 14

Table 1 – Dimensions of jacketed small prismatic cells . 11
Table 2 – Jacketed cylindrical cells dimensionally interchangeable with primary cells . 12
Table 3 – Jacketed cylindrical cells not dimensionally interchangeable with primary
cells . 13
Table 4 – Dimensions of button cells . 14
Table 5 – Discharge performance at 20 °C for small prismatic cells and cylindrical cells . 15
Table 6 – Discharge performance at 20 °C for button cells . 15
Table 7 – Discharge performance at 0 °C for small prismatic cells and cylindrical cells . 16
Table 8 – Discharge performance at 0 °C for button cells . 16
Table 9 – Endurance in cycles for small prismatic, button and cylindrical cells not
dimensionally interchangeable with primary cells . 17
Table 10 – Endurance in cycles for H or X cells . 18
Table 11 – Endurance in cycles for X cells . 18
Table 12 – Endurance in cycles for HR or XR cells . 19
Table 13 – Permanent charge endurance for L, M, H or X cells . 19
Table 14 – Permanent charge endurance for LT, MT or HT cells . 21
Table 15 – Permanent charge endurance for LU, MU or HU cells . 22
Table 16 – Overcharge at 0 °C . 23
Table 17 – Charge and discharge at +55 °C . 26
Table 18 – Constant discharge currents used for measurement of d.c. resistance . 27
Table 19 – Sequence of tests for type approval for small prismatic and for button cells . 28
Table 20 – Sequence of tests for type approval for cylindrical cells . 29
Table 21 – Recommended test sequence for batch acceptance . 30

---------------------- Page: 5 ----------------------
– 4 – 61951-2 © IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

SECONDARY CELLS AND BATTERIES CONTAINING
ALKALINE OR OTHER NON-ACID ELECTROLYTES –
PORTABLE SEALED RECHARGEABLE SINGLE CELLS –

Part 2: Nickel-metal hydride


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 standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61951-2 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.
This third edition cancels and replaces the second edition published in 2003 of which it
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• clause 4: addition of 2 parameters;
• clause 5: addition of cells type “S” and cells type “T”;
• subclause 6.1.2: addition of new cylindrical cells;
• subclause 7.8: addition of a specific test for “S” cells.

---------------------- Page: 6 ----------------------
61951-2 © IEC:2011 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
21A/484/FDIS 21A/487/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 61951 series can be found, under the general title Secondary cells
and batteries containing alkaline or other non-acid electrolytes – Portable sealed
rechargeable single cells, on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

---------------------- Page: 7 ----------------------
– 6 – 61951-2 © IEC:2011
SECONDARY CELLS AND BATTERIES CONTAINING
ALKALINE OR OTHER NON-ACID ELECTROLYTES –
PORTABLE SEALED RECHARGEABLE SINGLE CELLS –

Part 2: Nickel-metal hydride



1 Scope
This part of IEC 61951 specifies marking, designation, dimensions, tests and requirements for
portable sealed nickel-metal hydride, small prismatic, cylindrical and button rechargeable
single cells, suitable for use in any orientation.
2 Normative references
The following referenced documents are indispensable for the application 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, International Electrotechnical Vocabulary – Part 482: Primary and secondary
cells and batteries
IEC 60086 (all parts), Primary batteries
IEC 60086-1 (2006), Primary batteries – Part 1: General
IEC 60086-2 (2006), Primary batteries – Part 2: Physical and electrical specifications
IEC 60410, Sampling plans and procedures for inspection by attributes
IEC 61959, Secondary cells and batteries containing alkaline or other non-acid electrolytes –
Mechanical tests for sealed portable secondary cells and batteries
IEC 62133, 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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in the IEC 60050-482 and
the following apply.
3.1
nominal voltage
suitable approximate value of voltage used to designate or identify the voltage of a cell or
battery
NOTE 1 The nominal voltage of a sealed nickel-metal hydride rechargeable single cell is 1,2 V.
NOTE 2 The nominal voltage of a battery of n series connected cells is equal to n times the nominal voltage of a
single cell.

---------------------- Page: 8 ----------------------
61951-2 © IEC:2011 – 7 –
3.2
rated capacity
quantity of electricity C Ah (ampere-hours) declared by the manufacturer which a single cell
5
can deliver during a 5 h period when charging, storing and discharging under the conditions
specified in 7.3.2
3.3
small prismatic cell
cell in the form of a rectangular parallelepiped whose width and thickness dimensions are not
more than 25 mm
3.4
cylindrical cell
cell of circular cross-section in which the overall height is equal to, or greater than the overall
diameter
3.5
button cell
cell of circular cross-section in which the overall height is less than the overall diameter
3.6
nickel-metal hydride cell
cell containing a nickel hydroxide compound for the positive electrode, a hydrogen absorbing
alloy for the negative electrode, and potassium hydroxide or other alkaline solution as
electrolyte. Positive electrodes are isolated from negative electrodes by a separator
3.7
sealed cell
cell which remains closed and does not release either gas or liquid when operated within the
limits of charge and temperature specified by the manufacturer. The cell is equipped with a
safety device to prevent dangerously high internal pressure. The cell does not require addition
to the electrolyte and is designed to operate during its life in its original sealed state
NOTE The nickel-metal hydride cell, however, may release gas towards the end of its life due to the accumulation
of hydrogen in the cell.
3.8
portable cell
cell designed mainly for use in an easily hand-carried battery
3.9
surface temperature limited cell
cell which performs a function that prevents the temperature increase from a certain standard
point even at the moment of anomaly occurrence such as short circuit of cell
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;

---------------------- Page: 9 ----------------------
– 8 – 61951-2 © IEC:2011
g) ± 2 % for humidity.
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 each report of results.
5 Cell designation and marking
5.1 Cell designation
5.1.1 Small prismatic cells and cylindrical cells
5.1.1.1 General
Sealed nickel-metal hydride small prismatic rechargeable single cells and cylindrical
rechargeable single cells shall be designated by a letter L, M, H or X which signifies:
• low rate of discharge (L);
• medium rate of discharge (M);
• high rate of discharge (H);
• very high rate of discharge (X).
NOTE These cells are typically but not exclusively used for the following discharge rates:
• L up to 0,5 I A;
t
• M up to 3,5 I A;
t
• H up to 7,0 I A;
t
• X up to and above 7,0 I A.
t
When a cell is intended for permanent charge at elevated temperatures, typically higher than
40 °C, a letter "T" is placed after the letter L, M, H or X.
When a cell is intended for permanent charge at elevated temperatures, typically higher than
50 °C, a letter "U" is placed after the letter L, M, H or X.
When a cell is intended for surface temperature limitation, a letter “S” is placed after the letter
L or M.
When a cell is intended for rapid charge, typically at 1,0 I A, a letter "R" is placed after the
t
letter L, M, H or X.
5.1.1.2 Small prismatic cells
Sealed nickel-metal hydride small prismatic rechargeable single cells shall be designated by
the letters "HF" followed by a letter L, M, H or X followed by three groups of figures, each
group being separated by a solidus, as follows:
a) The two figures to the left of the first solidus shall indicate the maximum width specified
for the cell, expressed in millimetres, rounded up to the next whole number.
b) The two figures in the middle shall indicate the maximum thickness specified for the cell,
expressed in millimetres, rounded up to the next whole number.
c) The two figures to the right of the second solidus shall indicate the maximum height
specified for the cell, expressed in millimetres, rounded up to the next whole number.
EXAMPLE HFL 18/07/49 designation identifies a small prismatic cell of low discharge rate capability, with a
maximum width of 18 mm, a maximum thickness of 7 mm and a maximum height of 49 mm.

---------------------- Page: 10 ----------------------
61951-2 © IEC:2011 – 9 –
5.1.1.3 Cylindrical cells
Sealed nickel-metal hydride cylindrical rechargeable single cells shall be designated by the
letters "HR" followed by a letter L, M, H or X followed by two groups of figures, each group
being separated by a solidus, as follows:
a) The two figures to the left of the solidus shall indicate the maximum diameter specified for
the cell, expressed in millimetres, rounded up to the next whole number.
b) The two figures to the right of the solidus shall indicate the maximum height specified for
the cell, expressed in millimetres, rounded up to the next whole number.
When a manufacturer designs a cell with dimensions and tolerances which make it
interchangeable with a primary cell, the designation of Table 2 shall also be marked
on the cell.
EXAMPLE 1 HRL 33/62 designation identifies a cylindrical cell of low discharge rate capability, with a maximum
diameter of 33 mm and a maximum height of 61,5 mm.
EXAMPLE 2 HRLT 33/62 designation identifies a cylindrical cell of low discharge rate capability, intended for
permanent charge at elevated temperatures with a maximum diameter of 33 mm and a maximum height of 61,5 mm.
EXAMPLE 3 HRXR 23/43 designation identifies a cylindrical cell of very high discharge rate capability, intended for
rapid charge, with a maximum diameter of 23 mm and a maximum height of 43 mm.
For cells dimensionally interchangeable with primary cells, the following single or double
figures following the letter L, M, R or S may indicate:
• 20- Size D;
• 14- Size C;
• 6- Size AA;
• 03- Size AAA.
NOTE Cells dimensionally interchangeable with primary cells correspond to M type unless otherwise specified
For the purpose of this explanation, an example is given below.
EXAMPLE 4 HRMR03 designation identifies a sealed nickel-metal hydride cylindrical rechargeable single cell, of
medium discharge rate capability, also intended for rapid charge, dimensionally interchangeable with primary cell
and whose type designation is AAA.
5.1.2 Button cells
Sealed nickel-metal hydride button rechargeable single cells shall be designated by the letters
"HB" followed by two groups of figures separated by a solidus, as follows:
a) The three figures to the left of the solidus shall indicate the maximum diameter specified
for the cell, expressed in tenths of millimetres, rounded up to the next whole number.
b) The three figures to the right of the solidus shall indicate the maximum height specified for
the cell, expressed in tenths of millimetres, rounded up to the next whole number.
EXAMPLE HB 116/054 designation identifies a button cell, with a maximum diameter of 11,6 mm and a maximum
height of 5,4 mm.
5.2 Cell termination
This standard does not specify cell termination.
5.3 Marking
5.3.1 Small prismatic cells and cylindrical cells
Each jacketed cell supplied without connections shall carry
...