IEC TS 62257-8-1:2018

IEC TS 62257-8-1 ®
Edition 2.0 2018-02
TECHNICAL
SPECIFICATION
colour
inside
Recommendations for renewable energy and hybrid systems for rural
electrification –
Part 8-1: Selection of batteries and battery management systems for stand-alone
electrification systems – Specific case of automotive flooded lead-acid batteries
available in developing countries
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IEC TS 62257-8-1 ®
Edition 2.0 2018-02
TECHNICAL
SPECIFICATION
colour
inside
Recommendations for renewable energy and hybrid systems for rural

electrification –
Part 8-1: Selection of batteries and battery management systems for stand-alone

electrification systems – Specific case of automotive flooded lead-acid batteries

available in developing countries

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-5423-3

– 2 – IEC TS 62257-8-1:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Batteries and battery management system selection. 9
4.1 Battery technical characteristics . 9
4.1.1 Battery cases . 9
4.1.2 Battery terminals . 9
4.1.3 Electrolyte . 9
4.2 Comparative tests . 10
4.2.1 General . 10
4.2.2 Evaluation of the charge and discharge current for testing (I ) . 10
test
4.2.3 Test 1: battery endurance test . 11
4.2.4 Test 2: endurance test for battery and BMS . 15
4.2.5 Test 3: Battery storability test . 17
5 Documentation . 18
6 Installation rules . 19
6.1 Packing and shipping . 19
6.2 Environment . 19
6.3 Battery accommodation, housing . 20
6.3.1 General . 20
6.3.2 Provision against electrolyte hazard . 20
6.3.3 Prevention of short circuits and protection from other effects of electric
current . 21
6.3.4 Battery enclosures . 21
6.4 Final inspection . 22
6.5 Safety . 22
6.5.1 Safety provisions . 22
6.5.2 Safety Information . 22
6.6 Administrative formalities . 23
6.7 Recycling . 23

Figure 1 – Test 1 phases . 12
Figure 2 – Phase A battery endurance test . 13
Figure 3 – Phase B battery endurance test . 14
Figure 4 – Test 2 phases . 16
Figure 5 – Phase C battery – BMS endurance test . 16
Figure 6 – Test 3 phases . 17
Figure 7 – Phase D storability test . 18
Figure 8 – Marking for spillage prevention . 19

Table 1 – Testing procedure . 10
Table 2 – Evaluation of charge and discharge current (I ) . 11
test
Table 3 – Voltage regulation variation with temperature (examples) . 11

– 4 – IEC TS 62257-8-1:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RECOMMENDATIONS FOR RENEWABLE ENERGY AND
HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 8-1: Selection of batteries and battery management systems
for stand-alone electrification systems – Specific case of
automotive flooded lead-acid batteries
available in developing countries

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
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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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• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
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Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.

IEC 62257-8-1, which is a technical specification, has been prepared by IEC technical
committee 82: Solar photovoltaic energy systems.
This second edition cancels and replaces the first edition published in 2007. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) increase of the applicable voltage levels and removal of the 100 kW power limit;
b) removal of the word "small" from the description of these systems.
This technical specification is to be used in conjunction with the future parts of this series as
and when they are published.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
82/1330/DTS 82/1384/RVDTS
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 62257 series, under the general title: Recommendations for
renewable energy and hybrid systems for rural electrification, 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 "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication 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 TS 62257-8-1:2018 © IEC 2018
INTRODUCTION
The IEC 62257 series of documents intends to provide to different players involved in rural
electrification projects (such as project implementers, project contractors, project supervisors,
installers) with documents for the setting up of renewable energy and hybrid systems with AC
voltage below 1 000 V and DC voltage below 1 500 V.
These documents are recommendations:
• to choose the right system for the right place;
• to design the system;
• to operate and maintain the system.
These documents are focused only on rural electrification concentrating on, but not specific to,
developing countries. They are not considered as all-inclusive to rural electrification. The
documents try to promote the use of renewable energies in rural electrification; they do not
deal with clean mechanisms developments at this time (CO emissions, carbon credit, etc.).
Further developments in this field could be introduced in future steps.
This consistent set of documents is best considered as a whole with different parts
corresponding to items for safety, sustainability of systems and at the lowest life cycle cost
possible. One of the main objectives is to provide the minimum sufficient requirements
relevant to the field of application that is: small renewable energy and hybrid off-grid systems.
For rural electrification projects using PV systems, it is recommended to use solar batteries
defined in IEC 61427.
Nevertheless in many situations, it is a fact that most of the rural electrification projects are
implemented using locally made automotive flooded lead-acid batteries. But these products
are not designed for photovoltaic systems applications. There is presently no test to
discriminate, in a panel of models of such batteries, which one could provide the best service
as close as possible to the requirement of the general specification as a storage application
for small PV individual electrification systems (see IEC TS 62257-2) in an economically viable
way.
The purpose of IEC TS 62257-8-1 is to propose tests for automotive lead-acid batteries and
battery management systems used in small PV individual electrification systems.

RECOMMENDATIONS FOR RENEWABLE ENERGY AND
HYBRID SYSTEMS FOR RURAL ELECTRIFICATION –

Part 8-1: Selection of batteries and battery management systems
for stand-alone electrification systems – Specific case of
automotive flooded lead-acid batteries
available in developing countries

1 Scope
This part of IEC 62257 proposes simple, cheap, comparative tests in order to discriminate
easily, in a panel of automotive flooded lead-acid batteries, the most acceptable model for PV
individual electrification systems.
It could be particularly useful for project implementers to test in laboratories of developing
countries, the capability of locally made car or truck batteries to be used for their project.
Furthermore, battery-testing specifications usually need test equipment that is too costly and
too sophisticated to be applied in developing countries' laboratories.
The tests provided in this document allow assessment of the batteries' performances
according to the general specification of the project (see IEC TS 62257-2) and batteries
associated with their battery management system (BMS) in a short time and with common
technical means. They can be performed locally, as close as possible to the operating
conditions of the real site.
The document provides also regulations and installation conditions to be complied with in
order to ensure the life and proper operation of the installations as well as the safety of
people living in proximity to the installation.
This document is not a type approval standard. It is a technical specification to be used as
guidelines and does not replace any existing IEC standard on batteries.
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 – Part 482: Primary and
secondary cells and batteries
IEC 60050-482:2004/AMD1:2016
IEC TS 62257-6, Recommendations for renewable energy and hybrid systems for rural
electrification – Part 6: Acceptance, operation, maintenance and replacement
3 Terms and definitions
For the purposes of this document, the terms and definitions for secondary cells and batteries
given in IEC 60050-482 and the following apply.

– 8 – IEC TS 62257-8-1:2018 © IEC 2018
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
secondary cell
cell that is designed to be electrically recharged
Note 1 to entry: The recharge is accomplished by way of a reversible chemical reaction.
[SOURCE: IEC 60050-482:2004, 482-01-03]
3.2
storage battery
secondary battery
two or more secondary cells connected together and used as a source of electric energy
3.3
lead-acid battery
storage battery in which the electrodes are made mainly from lead and the electrolyte is a
sulphuric acid solution
3.4
terminal
pole
conductive part provided for the connection of a cell or battery to external conductors
3.5
density
commonly considered as the volumic mass, in kg/dm
Note 1 to entry: Density is also defined as a dimensionless magnitude expressing the ratio of the electrolyte mass
to the water mass occupying the same volume at 4 °C.
3.6
electrolyte
liquid or solid substance containing mobile ions that render it ionically conductive
Note 1 to entry: The electrolyte may be liquid, solid or a gel.
[SOURCE: IEC 60050-482:2004, 482-02-29]
3.7
dry charged battery
state of delivery of some types of secondary battery where the cells contain no electrolyte and
the plates are dry and in a charged state
[SOURCE: IEC 60050-482:2004, 482-05-30]
3.8
self-discharge
phenomenon by which a cell or battery loses energy in other ways than by discharge into and
external circuit
[SOURCE: IEC 60050-482:2004, 482-03-27]

3.9
nominal capacity
suitable approximate quantity of electricity, used to identify the capacity of a cell or a battery
Note 1 to entry: This value is usually expressed in ampere-hours (Ah).
3.10
rated capacity
quantity of electricity, declared by the manufacturer, that a cell or a
battery can deliver under specified conditions after a full charge
Note 1 to entry: The rated capacity shown on the battery label is given for a discharge period, which depends on
the technology used in the battery.
Note 2 to entry: The capacity of a battery is higher when it is discharged slowly. For example, variations are in the
order of 10 % to 20 % between a capacity measured over 5 h and a capacity measured over 100 h.
3.11
ambient temperature
temperature of the medium in the immediate vicinity of a battery
3.12
initial charge
commissioning charge given to a new battery to bring it to the fully charged state
3.13
cycling
set of operations that is carried out on a secondary cell or battery and is
repeated regularly in the same sequence
Note 1 to entry: In a secondary battery these operations may consist of a sequence of a discharge followed by a
charge of a charge followed by a discharge under specified conditions. This sequence may include rest periods.
[SOURCE: IEC 60050-482:2004, 482-05-28]
4 Batteries and battery management system selection
4.1 Battery technical characteristics
4.1.1 Battery cases
Battery cases shall be made of suitable materials capable of withstanding impacts and shocks
and resistant to acid.
4.1.2 Battery terminals
Terminals shall be protected against accidental short circuits. Positive and negative polarities
shall be identified.
4.1.3 Electrolyte
The electrolyte for lead acid batteries is prepared from special sulphuric acid for storage
batteries. It shall be colourless, odourless and free of all insoluble material deposits. As there
is no standard for such an electrolyte, impurity levels shall follow the battery manufacturer's
requirements.
The electrolyte level checking interval varies depending on:
• the type of battery;
• the temperature;
– 10 – IEC TS 62257-8-1:2018 © IEC 2018
• the use;
• the regulation algorithms of the charge controller;
• the battery's age;
• the quality of the distilled water;
• the PV resource.
The service interval would be determined from the above parameters and the electrolyte
reservoir size, which is a specification of the specific battery used. Care should be used to
ensure that the service interval is within the capability of the maintenance organization.
The batteries shall be designed so that electrolyte levels are able to be checked and so that
distilled water can be added.
NOTE 1 Faradic water consumption for vented batteries:
When a battery reaches its fully charged state, water electrolysis occurs according to Faraday’s law.
Under standard conditions:
3 3
1 Ah decomposes H O into 0,42 dm H + 0,21 dm O
2 2 2.
Decomposition of 1 cm (1 g) H O requires 3 Ah.
An estimation of water consumption of a battery is given by:
Battery H O (g) consumption = (X Ah charged – Y Ah discharged) × number of cells in battery / 3.
NOTE 2 The number of cells for a 12 V lead acid battery is 6.
4.2 Comparative tests
4.2.1 General
The proposed comparative tests are designed to discriminate the most appropriate batteries
taking into consideration the techno-economic context of the project.
These comparative tests include a sequence of three tests as indicated in Table 1.
IMPORTANT: all the batteries shall be tested simultaneously in order to ensure that they are
tested in the same conditions (insulation, temperature, etc.).
Table 1 – Testing procedure
Test 2: the couple battery-BMS is selected with
another endurance test
Test 1: the most durable batteries are first selected
See 4.2.4
with a battery endurance test
Test 3: in parallel to t
...