IEC 62877-1:2016

IEC 62877-1 ®
Edition 1.0 2016-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrolyte and water for vented lead acid accumulators –
Part 1: Requirements for electrolyte

Électrolyte et eau pour accumulateurs plomb-acide ouverts –
Partie 1: Exigences pour l'électrolyte

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IEC 62877-1 ®
Edition 1.0 2016-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrolyte and water for vented lead acid accumulators –

Part 1: Requirements for electrolyte

Électrolyte et eau pour accumulateurs plomb-acide ouverts –

Partie 1: Exigences pour l'électrolyte

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.220.20 ISBN 978-2-8322-3139-5

– 2 – IEC 62877-1:2016 © IEC 2016
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references. 5
3 Terms and definitions . 5
4 Preparation of electrolyte for lead-acid accumulators . 7
5 Physical properties of diluted sulfuric acid as electrolyte . 7
5.1 Dependence of acid density on temperature . 7
5.2 Relationship of electrolyte density on the content of sulfuric acid at 25 °C . 8
5.3 Electrolyte density compared to the state of discharge . 8
6 Requirements of sulfuric acid used as electrolyte . 8
6.1 Impurities of sulfuric acid of higher concentration degrees . 8
6.2 Impurities of filling acid . 8
6.3 Impurities of operating electrolyte . 9
7 Storage of electrolyte . 10
8 Remedy in the event of damage due to electrolyte . 10
Bibliography . 12

Table 1 – Correction of density from measuring temperature to reference/specified
temperature . 7
Table 2 – Acid density versus percentage of sulphuric acid at 25 °C . 8
Table 3 – Maximum allowed impurities of diluted sulfuric acid as filling electrolyte
for lead-acid batteries in the density range ≤ 1,30 kg/l . 9
Table 4 – Maximum allowed impurity of diluted acid as operating electrolyte
for lead-acid batteries in the density range ≤ 1,30 kg/l . 10

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROLYTE AND WATER FOR VENTED
LEAD ACID ACCUMULATORS –
Part 1: Requirements for electrolyte

FOREWORD
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62877-1 has been prepared by IEC technical committee 21:
Secondary cells and batteries.
The text of this standard is based on the following documents:
FDIS Report on voting
21/874/FDIS 21/881/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.

– 4 – IEC 62877-1:2016 © IEC 2016
A list of all parts of the IEC 62877 series can be found, under the general title Electrolyte and
water for vented lead acid accumulators, 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.
The contents of the corrigendum of May 2017 have been included in this copy.

ELECTROLYTE AND WATER FOR VENTED
LEAD ACID ACCUMULATORS –
Part 1: Requirements for electrolyte

1 Scope
This part of IEC 62877 applies to electrolyte and their components used for filling vented
lead-acid batteries, for example dry charged cells or batteries, and for electrolyte replacement
or electrolyte density adjustment of batteries in operation. This international standard defines
the composition, purity and properties of electrolyte to be applied where specific instructions
from the battery manufacturer are not available.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 62877-2, Electrolyte and water for vented lead acid accumulators – Part 2: Requirements
for water
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply
3.1
electrolyte
diluted sulfuric acid (H SO ) for lead-acid accumulators
2 4
Note 1 to entry: The electrolyte is prepared by mixing concentrated sulfuric acid or sulfuric acid with high density
of d > 1,30 kg/l and purified water to achieve the density values specified by the battery manufacturer or specified
in standards related to the type and battery design in question for a defined state of charge. Its purity meet the
requirements laid down in Table 3.
Note 2 to entry: Concentrated sulfuric acid is a colorless, highly corrosive and etching liquid with a density
1,84 kg/l.
3.2
water
purified water (H O) used for the preparation of electrolyte for batteries and for the
replacement (topping up) of water loss in the operating electrolyte due to decomposition of
water by overcharging and evaporation
Note 1 to entry: Purified water meet the requirements specified in IEC 62877-2.
3.3
filling electrolyte
diluted sulfuric acid to be used for the first filling of batteries or for the replacement of
contaminated operating electrolyte

– 6 – IEC 62877-1:2016 © IEC 2016
3.4
first filling
original filling of a battery carried out by the battery manufacturer or the user in accordance
with the applicable manufacturer’s instructions
3.5
operating electrolyte
electrolyte present in the battery following the first filling
Note 1 to entry: The density values and the degree of purity of the operating electrolyte may deviate from the
values of the filling electrolyte due to impurity input from replenishment by water and to elution from e.g.
separators, active material and electrode grids.
3.6
electrolyte density
value for the mass per volume expressed in kg/l
Note 1 to entry: The density varies with the battery´s state of charge, the electrolyte volume variation due to
water loss and the temperature.
3.7
specified density
density of the battery to be stated by the battery manufacturer valid at the maximum
electrolyte level (see 3.10 ) at full state of charge of the battery at the reference temperature
Note 1 to entry: It is related to the application and design of the battery.
3.8
reference temperature for analytical results
reference temperature for analytical results of electrolyte impurities which is 25 °C ± 1 °C
Note 1 to entry: Density values measured at temperatures deviating from this reference temperature are adjusted
accordingly.
3.9
measurement of the electrolyte density
measurement is carried out by densimeters, in which areometers (hydrometers) are used, or
by electronic devices based on e.g. on ultrasonic measurements
Note 1 to entry: The accuracy of the instrument is better than ± 0,001 kg/l.
3.10
electrolyte level
position of the electrolyte surface in the cell/battery, where the recommended tidal
movements are indicated by maximum and minimum electrolyte level marks to assist in water
replenishment
Note 1 to entry: Water replenishment should take place in a fully charged state to the upper limit, to avoid over
topping and electrolyte loss.
3.11
reference temperature
value specified by the battery manufacturer for the indication of properties, such as the
nominal electrolyte density, the maximum electrolyte level and the nominal capacity of the
battery
Note 1 to entry: The value of the nominal temperature for the indication of parameters may differ depending on
the battery type and application.
3.12
electrolyte additives
compounds which, added to the electrolyte, improve certain properties of the accumulator

Note 1 to entry: They shall be specified by the manufacturer. Other additives, not specified or not approved by the
battery manufacturer, should not be used as they may cause damage to the battery and thus endanger the
functional reliability.
Note 2 to entry: Examples of electrolyte additives are alkaline metal sulfates.
3.13
impurities
impurities from the electrolyte in practical use may cause damage to the battery and reduce
its performance
Note 1 to entry: The type and maximum permissible quantity of impurities are specified in Tables 3 and 4.
4 Preparation of electrolyte for lead-acid accumulators
The electrolyte is prepared from sulfuric acid of high concentration by pouring it into purified
water.
As concentrated and diluted sulfuric acid has a highly etching effect on human skin and
corrosive effect on clothes and many materials, and therefore the electrolyte shall be
prepared by the battery manufacturer or skilled personnel only.
NOTE The mixing of sulphuric acid of high concentrations with water releases a high amount of heat. To avoid
sudden splashing of hot acid, always pour acid into water, never the opposite. Pay attention to the safety data
sheets.
5 Physical properties of diluted sulfuric acid as electrolyte
5.1 Dependence of acid density on temperature
The value of acid densities obtained at the measuring temperature shall be converted to the
value of acid density at the reference temperature of 25 °C by following equation:
d = d + f (T – T )
n T d n
where
d is the acid density at 25 °C;
n
d is the acid density at measuring temperature T;
T
f is the correction factor according to Table 1;
d
T  is the measuring temperature;
T is the reference temperature 25 °C.
n
Table 1 – Correction of density from measuring temperature
to reference/specified temperature
a
Acid density d Correction factor f
n d
kg/l kg/l per K
1,10 0,000 50
1,15 0,000 60
1,20 0,000 70
1,30 0,000 75
a
The correction factor refers to the temperature range from 0 °C to 55 °C.

– 8 – IEC 62877-1:2016 © IEC 2016
5.2 Relationship of electrolyte density on the content of sulfuric acid at 25 °C
The following Table 2 presents the relationship between the density and the content of
sulphuric acid in the electrolyte.
Table 2 – Acid density versus percentage of sulphuric acid at 25 °C
Sulfuric acid content (H SO )
2 4
Acid density at 25 °C Mass ratio Amount of Concentration
kg/l H SO H SO H SO
2 4 2 4 2 4
% w/w mol/l g/l
1,100 15,18 1,704 166,98
1,110 16,45 1,863 182,60
1,120 17,80 2,034 199,36
1,130 19,15 2,208 216,40
1,140 20,47 2,381 233,36
1,150 21,81 2,558 250,70
1,160 23,11 2,735 268,07
1,170 24,39 2,911 285,36
1,180 25,63 3,086 302,43
1,190 26,90 3,266 320,11
1,200 28,12 3,443 337,44
1,210 29,34 3,622 355,01
1,220 30,55 3,803 372,71
1,230 31,78 3,989 390,89
1,240 32,98 4,173 408,95
1,250 34,18 4,360 427,25
1,260 35,40 4,551 446,04
1,270 36,60 4,743 464,82
1,280 37,81 4,938 483,97
1,290 38,93 5,124 502,20
1,300 40,10 5,319 521,30
5.3 Electrolyte density compared to the state of discharge
The electrolyte density decreases during discharge of a battery. Therefore the specified
electrolyte densities relate to a fully charged state. The permissible limit values shall be
specified by the battery manufacturer for the various battery types and applications.
6 Requirements of sulfuric acid used as electrolyte
6.1 Impurities of sulfuric acid of higher concentration degrees
The purity of sulfuric acid of higher concentration degrees shall be such, that after the
following dilution with water to values of ≤ 1,30 kg/l as filling electrolyte, the values given in
Table 3 are by no means exceeded.
6.2 Impurities of filling acid
The sulfuric acid used for filling lead-acid batteries shall be clear and colorless.

The impurities included in the acid shall not exceed any value quoted in Table 3.
This level of purity is required also for acid to be used a density higher than 1,30 kg/l, e.g. for
adjustment of the electrolyte density in batteries where an electrolyte loss has occurred.
Table 3 – Maximum allowed impurities of diluted sulfuric acid as filling electrolyte
for lead-acid batteries in the density range ≤ 1,30 kg/l
Cons. no. Impurities mg/l max.
1 Palladium (Pd), Platinium (Pt), Rhenium (Re) 0,05
2 Copper ( Cu )  0,5
3 Arsenic (As), Antimony (Sb), Bismuth (Bi), Tin (Sn), Selenium ( Se),
Tellurium (Te), Cadmium (Cd), Mercury (Hg),

– each individually
1,0
– total (all together)
2,0
4 Manganese (Mn), Chromium (Cr), Titanium (Ti), Nickel (Ni),
– each individually 0,2
5 Iron (Fe) 30
6 Cobalt (Co), Zink (Zn)
– each individually 1,0
– a total (all together) 2,0
7 halogens calculated as chloride 5
8 nitrogen in the form of nitrate 10
9 nitrogen in other form as e.g. ammonia 50
10 volatile organic acids calculated as acetic acid 20
11 oxidable organic substances calculated as KMnO consumption 30
12 annealing residue 250
6.3 Impurities of operating electrolyte
The sulfuric acid used for filling lead-acid batteries should be clear and colorless.
The impurities of the operating electrolyte shall not exceed any value quoted in Table 4.

– 10 – IEC 62877-1:2016 © IEC 2016
Table 4 – Maximum allowed impurity of diluted acid as operating electrolyte
for lead-acid batteries in the density range ≤ 1,30 kg/l
b
Cons. no. Impurities mg/l max.
a
1 Palladium (Pd), Platinium (Pt), Rhenium (Re) n.m.
Copper (Cu)
2 Tellurium (Te) and Selenium (Se) individually 1,0
3 Arsenic (As), Bismuth (Bi) , Cadmium (Cd) , Tin ( Sn)
– individually 3
– total (all together) 6
4 Antimony ( Sb)
– stationary cells with Planté or flat plates 3
– stationary cells with tubular plates and traction cells 10
5 Manganese (Mn), Chromium (Cr), Titanium (Ti), Nickel (Ni)
– Individually 0,2
6 Iron (Fe) 100
7 Cobalt (Co ), Zink (Zn)
– individually 1,0
– total (all together) 2,0
8 halogens calculated as chloride:
– stationary cells with Planté plates 30
– other stationary cells 100
– tractio
...