SIST EN 60993:2003 (HD 585 S1:1991)
(Main)Electrolyte for vented nickel-cadmium cells
Electrolyte for vented nickel-cadmium cells
Applies to electrolytes and their components when used in vented nickel-cadmium cells.
Elektrolyt für geschlossene wiederaufladbare Nickel-Cadmium-Zellen
Electrolyte pour éléments ouverts au nickel-cadmium
S'applique aux électrolytes et à leurs constituants pour utilisation dans les éléments ouverts au nickel-cadmium.
Electrolyte for vented nickel-cadmium cells
General Information
- Status
- Published
- Publication Date
- 31-Mar-2003
- Technical Committee
- ISCB - Secondary cells and batteries
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 01-Apr-2003
- Due Date
- 01-Apr-2003
- Completion Date
- 01-Apr-2003
Relations
- Effective Date
- 06-May-2014
- Effective Date
- 03-Feb-2026
- Effective Date
- 03-Feb-2026
Overview
SIST EN 60993:2003 (HD 585 S1:1991), "Electrolyte for vented nickel-cadmium cells," is a standardized framework developed by the Slovenski inštitut za standardizacijo (SIST) that provides key requirements for electrolytes and their constituents as used in vented nickel-cadmium (Ni-Cd) battery cells. The standard ensures consistency, safety, and performance by defining the required purity, composition, and physical properties for electrolytes, supporting manufacturers, operators, and maintenance personnel involved with Ni-Cd cell technology.
Key Topics
SIST EN 60993:2003 covers core aspects vital for the reliable operation of vented nickel-cadmium cells:
Scope and Purpose
- Applies to electrolytes used for filling, operating, and replacing in vented Ni-Cd cells.
- Focuses on guidance in the absence of manufacturer-specific instructions.
Electrolyte Composition
- Establishes purity needs for potassium hydroxide (KOH), water, and optional lithium hydroxide (LiOH) additives.
- Specifies clear, impurity-safe electrolytes to protect cell health.
Impurity Classification
- Categorizes impurities as critical, major, or minor based on impact on cell life and performance.
Physical and Chemical Properties
- Defines necessary electrolyte density ranges.
- Includes methods for checking impurity levels and maintaining operational electrolyte quality.
Preparation and Handling
- Guidelines for safe preparation using KOH and water.
- Emphasis on correct dissolution practices and materials compatibility.
Monitoring and Maintenance
- Recommendations for field measurement of electrolyte density, alkalinity, and carbonate levels.
- Guidance provided for adjustments and replacement when necessary.
Applications
The standard delivers practical value across several areas:
Battery Manufacturing
- Assists in selection and verification of suitable electrolytes during cell assembly.
- Enforces quality control over raw materials and finished batteries.
Testing and Quality Assurance
- Offers procedures for verifying electrolyte composition and purity, supporting laboratory and field testing.
Battery Operation and Maintenance
- Supports ongoing monitoring of electrolyte properties in operational environments.
- Provides maintenance personnel with actionable guidelines for replenishing or replacing electrolytes to maximize battery life cycle.
Industrial and Commercial Deployments
- Vital for sectors using vented nickel-cadmium cells, including backup power systems, transportation, renewable energy storage, and telecommunications.
Related Standards
Several other standards interact with or complement SIST EN 60993:2003 in ensuring consistent battery safety and operation:
- IEC 60993:1989
(Referenced as the international basis for SIST EN 60993) - ISO Standards (for testing and chemical analysis):
- ISO 990: Potassium hydroxide for industrial use - Method of assay
- ISO 993: Determination of sulphate content
- ISO 994: Determination of iron content
- ISO 995: Determination of silica content
- ISO 1550: Determination of sodium content
- ISO 2466: Sampling and test sample preparation
- ISO 2900: Determination of carbon dioxide content
- ISO 3177: Determination of chloride content
- ISO 3194: Determination of sulphur compounds
- ISO 3698: Determination of calcium and magnesium
- ISO 6353 Series: Reagents for chemical analysis
By adhering to SIST EN 60993:2003, organizations enhance the operational reliability of vented nickel-cadmium cells, streamline compliance with European and international quality benchmarks, and support safe, long-term battery usage in critical applications.
Get Certified
Connect with accredited certification bodies for this standard

IMQ S.p.A. (Certification)
Italian electrical product certification.

SLG Prüf- und Zertifizierungs GmbH
German testing and certification body.

UL Solutions
Global safety science company with testing, inspection and certification.
Sponsored listings
Frequently Asked Questions
SIST EN 60993:2003 (HD 585 S1:1991) is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Electrolyte for vented nickel-cadmium cells". This standard covers: Applies to electrolytes and their components when used in vented nickel-cadmium cells.
Applies to electrolytes and their components when used in vented nickel-cadmium cells.
SIST EN 60993:2003 (HD 585 S1:1991) is classified under the following ICS (International Classification for Standards) categories: 29.220.30 - Alkaline secondary cells and batteries. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 60993:2003 (HD 585 S1:1991) has the following relationships with other standards: It is inter standard links to SIST HD 585 S1:1997, SIST EN IEC 61204-7:2018, SIST EN IEC 62485-1:2018. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
SIST EN 60993:2003 (HD 585 S1:1991) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI SIST EN 60993:2003 (HD 585
S1:1991)
STANDARD
april 2003
Electrolyte for vented nickel-cadmium cells
ICS 29.220.30 Referenčna številka
SIST EN 60993:2003 (HD 585
S1:1991)(en)
© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno
EUROPEAN STANDARD EN 60993
NORME EUROPÉENNE
EUROPÄISCHE NORM July 2002
ICS 29.220.30 Supersedes HD 585 S1:1991
English version
Electrolyte for vented nickel-cadmium cells
(IEC 60993:1989)
Electrolyte pour éléments Elektrolyt für geschlossene
ouverts au nickel-cadmium wiederaufladbare Nickel-Cadmium-Zellen
(CEI 60993:1989) (IEC 60993:1989)
This European Standard was approved by CENELEC on 2002-07-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60993:2002 E
Foreword
The text of the International Standard IEC 60993:1989, prepared by SC 21A, Secondary cells and
batteries containing alkaline or other non-acid electrolytes, of IEC TC 21, Secondary cells and
batteries, was approved by CENELEC as HD 585 S1 on 1991-02-01.
This Harmonization Document was submitted to the formal vote for conversion into a European
Standard and was approved by CENELEC as EN 60993 on 2002-07-01.
The following date was fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2003-07-01
Annexes designated "informative" are given for information only.
In this standard, annexes A and B are informative.
__________
Endorsement notice
The text of the International Standard IEC 60993:1989 was approved by CENELEC as a European
Standard without any modification.
__________
NORME
CEI
INTERNATIONALE
IEC
INTERNATIONAL
Première édition
STAN DARD
First edition
1989-07
Electrolyte pour
éléments ouverts
au nickel-cadmium
Electrolyte for vented
nickel-cadmium cells
© IEC 1989 Droits de reproduction réservés
— Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni
No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun
any form or by any means, electronic or mechanical,
procédé, électronique ou mécanique, y compris la photo-
including photocopying and microfilm, without permission in
copie et les microfilms, sans l'accord écrit de l'éditeur.
writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http: //www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
L
PRICE CODE
International Electrotechnical Commission
IEC MenigyHapo maR 3neKTpoTe%HH4ecKan
HOMHCCHA
Pour prix, voir catalogue en vigueur
• •
For price, see current catalogue
I EC 993 © 3
CONTENTS
Page
FOREWORD 5
PREFACE 5
Clause
1. Scope 7
2. Object 7
3. Definitions 7
3.1 Classification of impurities
3.2 Filling electrolyte
3.3 Operating electrolyte
3.4 Replacement electrolyte 9
4. Preparation of the electrolyte 9
4.1 Requirements of potassium hydroxide (KOH), solid and
liquid, supplied for preparation of electrolytes 9
4.2 Requirements of water used for topping up and preparation
of electrolytes
4.3 Requirements of solid lithium hydroxide (LiOH, H 2O) used
as an additive for preparation of electrolytes 15
5. Requirements 15
for filling and replacement electrolytes
6. Physical and chemical requirements of electrolyte 17
6.1 Density of electrolyte 17
6.2 Minimum and maximum values of electrolyte densities 19
6.3 Purity of the electrolyte 19
APPENDIX A - (informative) 21
APPENDIX B - (informative) 23
993©IEC —5
INTERNATIONAL ELECTROTECHNICAL
COMMISSION
ELECTROLYTE FOR VENTED NICKEL-CADMIUM CELLS
FOREWORD
1)
The formal decisions or agreements of the IEC on technical matters,
prepared by Technical Committees on which all the National Committees
having a special interest therein are represented, express, as nearly
as possible, an international consensus of opinion on the subjects
dealt with.
2)
They have the form of recommendations for international use and they
are accepted by the National Committees in that sense.
3)
In order to promote international unification, the IEC expresses the
wish that all National Committees should adopt the text of the IEC
recommendation for their national rules in so far as national con-
ditions will permit. Any divergence between the IEC recommendation and
the corresponding national rules should, as far as possible, be clearly
indicated in the latter.
PREFACE
This standard has been prepared by Sub-Committee 21A: Alkaline secon-
dary cells and batteries, of IEC Technical Committee No. 21: Secondary
cells and batteries.
The text of this standard is based upon the following documents:
Six Months' Rule
Report on Voting
21A(CO)58
21A(CO)64
Full information on the voting for the approval of this standard can be
found in the Voting Report indicated in the above table.
993 IEC — 7 —
©
ELECTROLYTE FOR VENTED NICKEL-CADMIUM CELLS
1 Scope
This standard applies to electrolytes and their components when used
in vented nickel-cadmium cells.
These electrolytes are used:
- for filling cells supplied without filling electrolyte, and/or
-
for refilling cells if change of electrolyte is required, and/or
if the operating electrolyte needs to be topped up with water
provided no specific recommendations from the manufacturer are
available.
2. Object
The object of this standard is to define the composition, purity and
properties of electrolytes and their components for use in vented
nickel-cadmium cells and requirements for them in the absence of
specific recommendations from the manufacturer.
3. Definitions
For the purpose of this standard, the following definitions apply.
3.1 Classification of impurities
Impurities are classified according to their effect on cell life and
performance as far as the values given in the following tables are
exceeded.
-
Critical: impurities which have a detrimental effect on cell
operation and performance characteristics and which
result in an irreversible degradation of the cell;
- Major: impurities which reduce either performance character-
istics and/or life of the cell;
- Minor:
impurities which have no effect on cell life and/or
performance characteristics.
993 C©IEC
3.2 Filling electrolyte
Electrolyte used for the filling of new vented nickel-cadmium cells
prior to service.
3.3
Operating electrolyte
Electrolyte in use in vented nickel-cadmium cells. It will differ in
composition from the filling and replacement electrolyte by the addition
of water, absorption of carbon dioxide from the air and the transfer of
impurities from the internal components of the cell.
3.4 Replacement electrolyte
Electrolyte used to refill vented nickel-cadmium cells when the
operating electrolyte exceeds the impurity limits.
4. Preparation of the electrolyte
The electrolyte is prepared by dilution of a commercially available
potassium hydroxide solution of a higher concentration with purified
water or by dissolving solid potassium hydroxide in purified water.
If required, additives, for instance lithium hydroxide, should be
added according to the manufacturer's instructions.
Note.- Extreme caution should be exercised when dissolving solid
potassium hydroxide in water: considerable heat is generated
during the solution process.
It is essential that solid potassium hydroxide should always be
added to water; never add water to solid potassium hydroxide.
The inst
...



