IEC 61951-2:2011

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

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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

– 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

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

– 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
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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) 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.

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.
– 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.
61951-2 © IEC:2011 – 7 –
3.2
rated capacity
quantity of electricity C Ah (ampere-hours) declared by the manufacturer which a single cell
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;
– 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.

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 durable markings giving the
following minimum information:

– 10 – 61951-2 © IEC:2011
• sealed rechargeable nickel-metal hydride or Ni-MH;
• designation as specified in 5.1 (in addition, it is permissible for a manufacturer to use his
own type designation);
• rated capacity;
• nominal voltage;
• recommended charge rate and time or permanent charge current for "T" cells;
• polarity;
• date of manufacture (which may be in code);
• name or identification of manufacturer or supplier.
NOTE In general, sealed nickel-metal hydride rechargeable single cells with connection tabs need no labels if
they form an integral part of a battery, in which case, the battery itself is marked with the above information.
5.3.2 Button cells
Each button cell supplied without connection shall carry durable markings giving the following
minimum information:
• designation as specified in 5.1;
• polarity;
• date of manufacture (which may be in code);
• name or identification of manufacturer or supplier.
6 Dimensions
6.1 Small prismatic cells and cylindrical cells
6.1.1 General
Figures 1 and 2 show the shape of the cells.

61951-2 © IEC:2011 – 11 –
Thickness
Width
Diameter
(+)
(+)
(–)
(–)
IEC  1140/03 IEC  1141/03
Figure 1 – Jacketed cylindrical cells Figure 2 – Jacketed small
prismatic cells
6.1.2 Small prismatic cells
Table 1 shows the dimensions for jacketed small prismatic cells.
Table 1 – Dimensions of jacketed small prismatic cells
Width Thickness Height
Cell designation
mm mm mm
HF 15/08/49 14,5 7,4 48,2
HF 15/09/49 14,5 8,3 48,2
a
HF 16/07/34 16,0 6,6 34,0 0
0 –1,0
HF 18/07/36 17,3 6,1 35,7
–0,7
HF 18/07/49 17,3 6,1 48,2
HF 18/09/49 17,3 8,3 48,2
–1,0
HF 18/07/68 17,3 6,1 67,3
HF 18/11/68 17,3 10,7 67,3
HF 18/18/68 17,3 17,3 67,3 0
–1,0
–1,5
HF 23/11/68 22,7 10,7 67,3
HF 23/15/68 22,7 14,5 67,3
a
New cell.
Height
Height
– 12 – 61951-2 © IEC:2011
6.1.3 Cylindrical cells
6.1.3.1 Cells dimensionally interchangeable with primary cells
Table 2 gives the requirements relative to the dimensions for jacketed cylindrical cells which
are dimensionally interchangeable with primary cells.
Table 2 – Jacketed cylindrical cells dimensionally interchangeable with primary cells
Type Dimensions (mm)
Cell Corresponding
Nominal
designation A B C D
E F G Φ ΦP
Designa- primary cell
d
voltage
tion CEI 60086
(reference)
(V)
a c
b
Max Min Min - Max Max Min Min Max Min Max

R03
HR03 AAA 1,2 44,5 (43,3) 4,3 - 0,5 3,8 (2,0) 0,8 10,5 9,5 0,4
LR03
R6
HR6 AA 50,5 (49,2) 7,0 - 0,5 5,5 (4,2) 1,0 14,5 13,5 0,5
LR6
R14
HR14 C 50,0 (48,6) 13,0 - 0,9 7,5 (5,5) 1,5 26,2 24,9 1,0
LR14
R20
HR20 D 61,5 (59,5) 18,0 - 1,0 9,5 (7,8) 1,5 34,2 32,3 1,0
LR20
NOTE Figures in parentheses are reference values.
a
Cell designations shall be in accordance with the nomenclature rules given in IEC 60086-1.
b
In some countries, these cell types are also known as AAA (R 03); AA (R 6); C (R 14); D (R 20).
c
Carbon zinc cells (R) and alkaline primary cells (LR) shall be compliant with the provisions of IEC 60086-2, respectively.
d
There is no specification for the value “D” for sealed nickel-metal hydride cylindrical rechargeable single cells
interchangeable with primary cells.
F
(+)
D
C
∅
IEC  939/11
Figure 3 – Jacketed cells dimensionally interchangeable with primary cells
The cell dimensions of Figure 3 are given below:
a) A: maximum overall height of the cell;
b) B: minimum distance between the flats of the positive and the negative contacts;
c) C: minimum outer diameter of the negative flat contact surface;
d) D: maximum inner diameter of the negative flat contact surface;

∅P
B
G
E
E
A
61951-2 © IEC:2011 – 13 –
e) E: maximum recess of the negative flat contact surface;
f) F: maximum diameter of the positive contact within the specified projection height;
g) G: minimum projection of the flat positive contact;
h) ∅: maximum and minimum diameters of the cell;
i) ∅P: concentricity of the positive contact.
6.1.3.2 Cells not dimensionally interchangeable with primary cells
Table 3 shows the dimensions for jacketed cylindrical cells not dimensionally interchangeable
with primary cells.
Table 3 – Jacketed cylindrical cells not dimensionally interchangeable
with primary cells
a
Cell designation Diameter Height
mm mm
HR 11/45 10,5 44,5
HR 11/51 10,5 50,5
HR 11/67 10,5 67,0
HR 15/43 14,5 43,0
HR 15/49 14,5 49,0 0
–1,5
HR 15/51 14,5 50,5
b
HR 15/67 15,0 67,0
HR 17/29 17,0 28,5
–0,7
HR 17/43 17,0 43,0
HR 17/50 17,0 50,0
HR 17/67 17,0 67,0
–2,0
b
HR 18/44 18,0 43,5
b
HR 18/67 18,0 67,0
b
HR 19/67 19,0 67,0
HR 23/34 23,0 34,0
HR 23/43 23,0 43,0
–1,5
b
HR 23/44 23,0 43,5
b
HR 23/50 23,0 50,0
b
HR 23/60 23,0 61,0
HR 26/47 25,8 47,0
–1,0
HR 26/50 25,8 50,0
HR 33/36 33,0 36,0
–2,0
HR 33/62 33,0 61,5
HR 33/91 33,0 91,0
0 / –2,5
b
0 / –2,0
HR 34/60 33,5 59,5
a
The letters HR to be followed by L, M, H or X and T and/or R as appropriate (see 5.1).
b
8 new cells.
– 14 – 61951-2 © IEC:2011
6.2 Button cells
Cells shall be constructed as design I or II.

DESIGN I DESIGN II
IEC  2883/2000 IEC  2884/2000

NOTE The polarity of design I is not standardized.
Figure 4 – Button cells
Table 4 shows the dimensions of sealed nickel-metal hydride button rechargeable single cells.
Table 4 – Dimensions of button cells

Overall diameter d Overall height h
Cell designation
mm mm
HB 079/054 7,9 5,4
–1,0
HB 116/054 11,6 5,4
HB 156/064 15,6 6,4
HB 222/048 22,2 4,8
–0,6
HB 252/061 25,2 6,1
–0,3
HB 252/065 25,2 6,5
HB 252/078 25,2 7,8
HB 347/060 34,7 6,0
7 Electrical tests
7.1 General
Charge and discharge currents for the tests in accordance with this clause and with Clause 5
shall be based on the rated capacity, (C Ah). These currents are expressed as multiples
of I A, where I A = C Ah/1 h.
t t 5
In all tests, except where noted, no leakage of electrolyte in liquid form shall be observed.
7.2 Charging procedure for test purposes
Unless otherwise stated in this standard, the charging procedure for test purposes shall be
carried out in an ambient temperature of 20 °C ± 5 °C and a relative humidity of 65 % ± 20 %,
at a constant current of 0,1 I A, for 16 h. The tests shall be performed within one month of the
t
arrival date or the purchasing date.
Prior to charging, the cell shall be discharged in an ambient temperature of 20 °C ± 5 °C, at a
constant current of 0,2 I A, down to a final voltage of 1,0 V.
t
61951-2 © IEC:2011 – 15 –
7.3 Discharge performance
7.3.1 General
The following discharge tests shall be carried out in the sequence given.
7.3.2 Discharge performance at 20 °C
The cell shall be charged in accordance with 7.2. After charging, the cell shall be stored in an
ambient temperature of 20 °C ± 5 °C, for not less than 1 h and not more than 4 h.
The cell shall then be discharged in an ambient temperature of 20 °C ± 5 °C and as specified
in Tables 5 or 6. The duration of discharge shall be not less than the values specified in
Tables 5 or 6.
The 0,2 I A discharge test is performed in order to verify the declared rated capacity
t
of the cell.
Table 5 – Discharge performance at 20 °C for small prismatic cells and cylindrical cells
Minimum discharge duration
Discharge conditions
h/min
Rate of constant
Final voltage Cell designation
current
A V L/LT/LU/LS M/MT/MU/MS H/HT/HU X
a
0,2 I
1,0 5 h 5 h 5 h 5 h
t
1,0 I 0,9 – 42 min 48 min 54 min
t
b
5,0 I 0,8 – – 6 min 9 min
t
b
10,0 I 0,7 – – – 4 min
t
a
Five cycles are permitted for this test. The test shall be terminated at the end of the first cycle which meets the
requirement.
b
Prior to the 5 I A and 10 I A tests, a conditioning cycle may be included if necessary. This cycle shall consist
t t
of charging at 0,1 I A in accordance with 7.2 and discharging at 0,2 I A in an ambient temperature of
t t
20 °C ± 5 °C according to 7.3.2.
Table 6 – Discharge performance at 20 °C for button cells
Discharge conditions
Minimum discharge
duration
Rate of Final
constant current voltage
h/min
A V
a
0,2 I 1,0 5 h
t
1,0 I 0,9 35 min
t
a
Five cycles are permitted for this test. The test shall be terminated at the end of
the first cycle which meets the requirement.

7.3.3 Discharge performance at 0 °C
The cell shall be charged in accordance with 7.2. After charging, the cell shall be stored, in an
ambient temperature of 0 °C ± 2 °C for not less than 16 h and not more than 24 h.
The cell shall then be discharged in an ambient temperature of 0 °C ± 2 °C and as specified
in Tables 7 or 8. The duration of discharge shall be not less than the values specified in
Tables 7 or 8.
– 16 – 61951-2 © IEC:2011
Table 7 – Discharge performance at 0 °C for small prismatic cells and cylindrical cells
Minimum discharge duration
Discharge conditions
h/min
Rate of Final voltage Cell designation
constant current
L/LT/LU/LS M/MT/MU/MS H/HT/HU X
A V
0,2 I 1,0 2 h 4 h 4 h 4 h 30 min
t
1,0 I 0,9 – 36 min 42 min 48 min
t
2,0 I a 0,8 – – 15 min 21 min
t
3,0 I a 0,8 – – – 12 min
t
a
Prior to the 2,0 I A and 3,0 I A tests, a conditioning cycle may be included if necessary. This cycle shall
t t
consist of charging at 0,1 I A in accordance with 7.2 and discharging at 0,2 I A in an ambient temperature of
t t
20 °C ± 5 °C according to 7.3.2.
Table 8 – Discharge performance at 0 °C for button cells
Discharge conditions
Minimum discharge
duration
Rate of Final
constant current voltage
h/min
A V
0,2 I 1,0 4 h
t
1,0 I 0,9 27 min
t
7.3.4 Discharge performance for rapid charge cells (R cells)
R cells shall be charged at a constant current of 1,0 I A for 1,2 h or other appropriate charge
t
termination method as recommended by the cell manufacturer, followed by a charge
at 0,1 I A for 2 h, in an ambient temperature of 20 °C ± 5 °C. After charging, the cell shall be
t
stored and discharged as specified in 7.3.2 and 7.3.3.
The duration of discharge shall be not less than the values specified in Table 5 for discharge
at 20 °C ± 5 °C and in Table 7 for discharge at 0 °C ± 2 °C.
7.4 Charge (capacity) retention
The charge (capacity) retention shall be determined by the following test. After charging in
accordance with 7.2, the cell shall be stored on open circuit for 28 days. The average ambient
temperature shall be 20 °C ± 2 °C. The temperature may be allowed to vary within the range
of 20 °C ± 5 °C for short periods during the storage.
The cells shall be discharged under the conditions specified in 7.3.2 at a rate of 0,2 I A.
t
The duration of discharge after 28 days storage at 20 °C shall be not less than:
• 3 h for small prismatic cells and cylindrical cells;
• 3 h 45 min for button cells.

61951-2 © IEC:2011 – 17 –
7.5 Endurance
7.5.1 Endurance in cycles
7.5.1.1 General
Prior to the endurance in cycles test, the cell shall be discharged at a constant current
of 0,2 I A to a final voltage of 1,0 V.
t
The following endurance test shall then be carried out, irrespective of cell designation, in an
ambient temperature of 20 °C ± 5 °C. Charge and discharge shall be carried out at constant
current throughout, in accordance with the conditions specified in Tables 9, 10, 11 and 12.
Precautions shall be taken to prevent the cell-case temperature from rising above 35 °C
during the test, by providing a forced air draught if necessary.
NOTE The actual cell temperature, not the ambient temperature, determines cell performance.
7.5.1.2 Small prismatic, button and cylindrical cells not dimensionally
interchangeable with primary cells
Table 9 – Endurance in cycles for small prismatic, button and cylindrical cells not
dimensionally interchangeable with primary cells
Stand in
Cycle number Charge Discharge
charged condition
a
1 0,10 I A for 16 h None 0,25 I A for 2 h 20 min
t t
a
2 to 48 0,25 I A for 3 h 10 min None 0,25 I A for 2 h 20 min
t t
49 0,25 I A for 3 h 10 min None 0,25 I A to 1,0 V
t t
b
50 0,10 I A for 16 h 1 h to 4 h 0,20 I A to 1,0 V
t t
a
If the cell voltage drops below 1,0 V, discharge may be discontinued.
b
It is permissible to allow sufficient open-circuit rest time after the completion of discharge at cycle 50, so as to
start cycle 51 at a convenient time. A similar procedure may be adopted at cycles 100, 150, 200, 250, 300, 350,
400 and 450.
Cycles 1 to 50 shall be repeated until the discharge duration on any 50th cycle becomes less
than 3 h. At this stage, a repeat capacity measurement as specified for cycle 50 shall be
carried out.
The endurance test is considered complete when two such successive capacity cycles give a
discharge duration of less than 3 h. The total number of cycles obtained when the test is
completed shall be not less than:
• 400 for small prismatic cells;
• 500 for L/LR, M/MR, H/HR or X/XR cells;
• 50 for LT/LU, MT/MU or HT/HU cells;
• 500 for button cells.
7.5.1.3 Cylindrical cells dimensionally interchangeable with primary cells
The cell shall be tested in accordance with 7.5.1.2. The total number of cycles obtained when
the test is completed shall be not less than:
• 500 for AAA cells with a rated capacity less than 800 mAh;
• 300 for AAA cells with a rated capacity of 800 mAh or more;
• 500 for AA cells with a rated capacity less than 2 100 mAh;
• 300 for AA cells with a rated capacity of 2 100 mAh or more;
• 500 for D and C cells.
– 18 – 61951-2 © IEC:2011
7.5.1.4 Cylindrical cells (accelerated test procedures)
7.5.1.4.1 General
In order to accelerate the test or to use cycling conditions approximating those in actual
applications, one of the following alternative procedures, shown in Tables 10, 11 and 12,
relevant to the cell may be carried out as an alternative to 7.5.1.2.
7.5.1.4.2 H or X cells
Table 10 – Endurance in cycles for H or X cells
Total duration
Stand in
Cycle number Charge Discharge including
charged condition
subsequent rest
1 0,1 I A for 16 h 30 min 1,0 I A to 1,0 V 90 min
t t
a
2 to 48 0,3 I A for 4h 30 min 1,0 I A to 1,0 V 90 min
t t
a
49 0,3 I A for 4h 24 h 1,0 I A to 1,0 V 90 min
t t
b
50 0,1 I A for 16 h 1 h to 4h 0,2 I A to 1,0 V
t t
a
Or appropriate charge termination, as recommended by the manufacturer.
b
It is permissible to allow sufficient open-circuit re
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