Secondary cells and batteries for renewable energy storage - General requirements and methods of test - Part 1: Photovoltaic off-grid application

IEC 61427-1:2013 is part of a series which gives general information relating to the requirements for the secondary batteries used in photovoltaic energy systems (PVES) and to the typical methods of test used for the verification of battery performances. This part deals with cells and batteries used in photovoltaic off-grid applications. This standard is applicable to all types of secondary batteries.

Wiederaufladbare Zellen und Batterien für die Speicherung erneuerbarer Energien - Allgemeine Anforderungen und Prüfverfahren - Teil 1: Photovoltaische netzunabhängige Anwendung

Accumulateurs pour le stockage de l'énergie renouvelable - Exigences générales et méthodes d'essais - Partie 1: Applications photovoltaiques hors réseaux

La CEI 61427-1:2013 fait partie d'une série qui donne des informations générales relatives aux exigences applicables aux accumulateurs utilisés dans les systèmes photovoltaïques (SPV) et aux méthodes d'essais spécifiques utilisées pour la vérification des performances de l'accumulateur. La présente partie traite des éléments et batteries utilisés dans les applications photovoltaïques hors réseaux. La présente norme s'applique à tous les types d'accumulateurs.

Sekundarni členi in baterije za shranjevanje obnovljive energije - Splošne zahteve in preskusne metode - 1. del: Uporaba fotonapetostnih elementov zunaj elektroenergetskega omrežja (IEC 61427-1:2013)

Ta del serije standardov IEC 61427 podaja splošne informacije, povezane z zahtevami za sekundarne baterije, ki se uporabljajo v fotonapetostnih energetskih sistemih (PVES), in značilnimi preskusnimi metodami, ki se uporabljajo za preverjanje zmogljivosti baterije. Ta del opisuje člene in baterije, ki se uporabljajo zunaj elektroenergetskega omrežja.

General Information

Status
Published
Publication Date
25-Jul-2013
Current Stage
6060 - Document made available
Due Date
28-Aug-2013
Completion Date
26-Jul-2013

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SLOVENSKI STANDARD
SIST EN 61427-1:2014
01-maj-2014
1DGRPHãþD
SIST EN 61427:2006

6HNXQGDUQLþOHQLLQEDWHULMH]DVKUDQMHYDQMHREQRYOMLYHHQHUJLMH6SORãQH]DKWHYH

LQSUHVNXVQHPHWRGHGHO8SRUDEDIRWRQDSHWRVWQLKHOHPHQWRY]XQDM
HOHNWURHQHUJHWVNHJDRPUHåMD ,(&

Secondary cells and batteries for Renewable Energy Storage - General Requirements

and methods of test - Part 1: Photovoltaic Off grid application

Eléments et batteries d'accumulateurs pour le stockage des énergies renouvelables -

Prescriptions générales et méthodes d'essai - Partie 1: Application photovoltaique isolée

du réseau électrique
Ta slovenski standard je istoveten z: EN 61427-1:2013
ICS:
27.160 6RQþQDHQHUJLMD Solar energy engineering
29.220.20 .LVOLQVNLVHNXQGDUQLþOHQLLQ Acid secondary cells and
EDWHULMH batteries
SIST EN 61427-1:2014 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 61427-1:2014
---------------------- Page: 2 ----------------------
SIST EN 61427-1:2014
EUROPEAN STANDARD
EN 61427-1
NORME EUROPÉENNE
July 2013
EUROPÄISCHE NORM
ICS 27.160; 29.220.20 Supersedes EN 61427:2005
English version
Secondary cells and batteries for renewable energy storage -
General requirements and methods of test -
Part 1: Photovoltaic off-grid application
(IEC 61427-1:2013)
Accumulateurs pour le stockage de Wiederaufladbare Zellen und Batterien für
l'énergie renouvelable - die Speicherung erneuerbarer Energien -
Exigences générales et méthodes Allgemeine Anforderungen und
d'essais - Prüfverfahren -
Partie 1: Applications photovoltaïques Teil 1: Photovoltaische netzunabhängige
hors réseaux Anwendung
(CEI 61427-1:2013) (IEC 61427-1:2013)

This European Standard was approved by CENELEC on 2013-05-28. 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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,

the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,

Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,

Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2013 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61427-1:2013 E
---------------------- Page: 3 ----------------------
SIST EN 61427-1:2014
EN 61427-1:2013 - 2 -
Foreword

The text of document 21/793/FDIS, future edition 1 of IEC 61427-1, prepared by IEC/TC 21 "Secondary

cells and batteries" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as

EN 61427-1:2013.
The following dates are fixed:
• latest date by which the document has (dop) 2014-02-28
to be implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2016-05-28
• latest date by which the national
standards conflicting with the
document have to be withdrawn
This document supersedes EN 61427:2005.

EN 61427-1:2013 includes the following significant technical changes with respect to EN 61427:2005:

a) a restructuration of the previous edition of the document;

b) a clarification of the different clauses with regard to conditions of use, general requirements, functional

characteristics, general tests conditions, test method and recommended use of tests, the aim being to

ensure a better understanding by the end user;

c) a clear distinction between on-grid and off-grid applications for future markets needs.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent

rights.
Endorsement notice

The text of the International Standard IEC 61427-1:2013 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following note has to be added for the standard indicated:

IEC 60721-1 NOTE Harmonised as EN 60721-1.
---------------------- Page: 4 ----------------------
SIST EN 61427-1:2014
- 3 - EN 61427-1:2013
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.

NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
IEC 60050 Series International Electrotechnical vocabulary (IEV) - -
IEC 60622 - Secondary cells and batteries containing EN 60622 -
alkaline or other non-acid electrolytes -
Sealed nickel-cadmium prismatic
rechargeable single cells
IEC 60623 - Secondary cells and batteries containing EN 60623 -
alkaline or other non-acid electrolytes -
Vented nickel-cadmium prismatic
rechargeable single cells
IEC 60896-11 - Stationary lead-acid batteries - EN 60896-11 -
Part 11: Vented types - General requirements
and methods of tests
IEC 60896-21 - Stationary lead-acid batteries - EN 60896-21 -
Part 21: Valve regulated types - Methods of
test
IEC 61056-1 - General purpose lead-acid batteries (valve- EN 61056-1 -
regulated types) -
Part 1: General requirements, functional
characteristics - Methods of test
IEC 61836 - Solar photovoltaic energy systems - - -
Terms, definitions and symbols
IEC 61951-1 - Secondary cells and batteries containing EN 61951-1 -
alkaline or other non-acid electrolytes -
Portable sealed rechargeable single cells -
Part 1: Nickel-cadmium
IEC 61951-2 - Secondary cells and batteries containing EN 61951-2 -
alkaline or other non-acid electrolytes -
Portable sealed rechargeable single cells -
Part 2: Nickel-metal hydride
IEC 61960 - Secondary cells and batteries containing EN 61960 -
alkaline or other non-acid electrolytes -
Secondary lithium cells and batteries for
portable applications
IEC 62259 - Secondary cells and batteries containing EN 62259 -
alkaline or other non-acid electrolytes -
Nickel-cadmium prismatic secondary single
cells with partial gas recombination
---------------------- Page: 5 ----------------------
SIST EN 61427-1:2014
---------------------- Page: 6 ----------------------
SIST EN 61427-1:2014
IEC 61427-1
Edition 1.0 2013-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Secondary cells and batteries for renewable energy storage – General
requirements and methods of test –
Part 1: Photovoltaic off-grid application
Accumulateurs pour le stockage de l'énergie renouvelable – Exigences
générales et méthodes d'essais –
Partie 1: Applications photovoltaïques hors réseaux
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX R
ICS 27.160; 29.220.20 ISBN 978-2-83220-763-5

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 7 ----------------------
SIST EN 61427-1:2014
– 2 – 61427-1  IEC:2013
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope ............................................................................................................................... 6

2 Normative references ....................................................................................................... 6

3 Terms and definitions ....................................................................................................... 7

4 Conditions of use.............................................................................................................. 7

4.1 General ................................................................................................................... 7

4.2 Photovoltaic energy system ..................................................................................... 7

4.3 Secondary cells and batteries .................................................................................. 7

4.4 General operating conditions ................................................................................... 8

4.4.1 General ....................................................................................................... 8

4.4.2 Autonomy time............................................................................................. 8

4.4.3 Typical charge and discharge currents ........................................................ 8

4.4.4 Daily cycle ................................................................................................... 8

4.4.5 Seasonal cycle ............................................................................................ 8

4.4.6 Period of high state of charge ...................................................................... 9

4.4.7 Period of sustained low state of charge ....................................................... 9

4.4.8 Electrolyte stratification ............................................................................... 9

4.4.9 Storage ....................................................................................................... 9

4.4.10 Operating temperature ............................................................................... 10

4.4.11 Charge control ........................................................................................... 11

4.4.12 Physical protection .................................................................................... 11

5 General requirements ..................................................................................................... 11

5.1 Mechanical endurance ........................................................................................... 11

5.2 Charge efficiency .................................................................................................. 12

5.3 Deep discharge protection ..................................................................................... 12

5.4 Marking ................................................................................................................. 12

5.5 Safety.................................................................................................................... 12

5.6 Documentation ...................................................................................................... 12

6 Functional characteristics ............................................................................................... 13

7 General test conditions ................................................................................................... 13

7.1 Accuracy of measuring instruments ....................................................................... 13

7.2 Preparation and maintenance of test batteries ....................................................... 13

8 Test method ................................................................................................................... 13

8.1 Capacity test ......................................................................................................... 13

8.2 Generic cycling endurance test.............................................................................. 14

8.3 Charge retention test ............................................................................................. 14

8.4 Cycling endurance test in photovoltaic applications (extreme conditions) .............. 14

8.4.1 General ..................................................................................................... 14

8.4.2 Phase A: shallow cycling at low state of charge (see Table 5) ................... 15

8.4.3 Phase B: shallow cycling at high state of charge (see Table 6) .................. 15

8.4.4 Residual capacity determination ................................................................ 16

8.4.5 Test termination......................................................................................... 16

8.4.6 Water consumption of flooded battery types and cells with partial gas

recombination ............................................................................................ 16

8.4.7 Requirements ............................................................................................ 16

9 Recommended use of tests ............................................................................................ 17

---------------------- Page: 8 ----------------------
SIST EN 61427-1:2014
61427-1  IEC:2013 – 3 –

9.1 Type test ............................................................................................................... 17

9.2 Acceptance test ..................................................................................................... 17

9.2.1 Factory test ............................................................................................... 17

9.2.2 Commissioning test ................................................................................... 17

Bibliography .......................................................................................................................... 18

Table 1 – Limit values for storage conditions of batteries for photovoltaic applications ......... 10

Table 2 – Limit values for operating conditions of batteries for photovoltaic

applications .......................................................................................................................... 10

Table 3 – Battery Ah-efficiency at different states of charge at the reference

temperature and a daily depth of discharge of less than 20 % of the rated capacity .............. 12

Table 4 – Typical capacity ratings of batteries in photovoltaic applications ............................ 14

Table 5 – Phase A – Shallow cycling at low state of charge .................................................. 15

Table 6 – Phase B – Shallow cycling at high state of charge ................................................. 16

---------------------- Page: 9 ----------------------
SIST EN 61427-1:2014
– 4 – 61427-1  IEC:2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SECONDARY CELLS AND BATTERIES
FOR RENEWABLE ENERGY STORAGE –
GENERAL REQUIREMENTS AND METHODS OF TEST –
Part 1: Photovoltaic off-grid application
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 61427-1 has been prepared by IEC technical committee 21:

Secondary cells and batteries.

This first edition cancels and replaces the second edition of IEC 61427 published in 2005.This

edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) a restructuration of the previous edition of the document;

b) a clarification of the different clauses with regard to conditions of use, general

requirements, functional characteristics, general tests conditions, test method and

recommended use of tests, the aim being to ensure a better understanding by the end

user;

c) a clear distinction between on-grid and off-grid applications for future markets needs.

---------------------- Page: 10 ----------------------
SIST EN 61427-1:2014
61427-1  IEC:2013 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
21/793/FDIS 21/802/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 in the IEC 61427 series, published under the general title Secondary cells

and batteries for renewable energy storage – General requirements and methods of test, can

be found 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: 11 ----------------------
SIST EN 61427-1:2014
– 6 – 61427-1  IEC:2013
SECONDARY CELLS AND BATTERIES
FOR RENEWABLE ENERGY STORAGE –
GENERAL REQUIREMENTS AND METHODS OF TEST –
Part 1: Photovoltaic off-grid application
1 Scope

This part of the IEC 61427 series gives general information relating to the requirements for

the secondary batteries used in photovoltaic energy systems (PVES) and to the typical

methods of test used for the verification of battery performances. This part deals with cells

and batteries used in photovoltaic off-grid applications.

NOTE The part 2 of this series will cover cells and batteries used in “renewable energy storage in on-grid

applications”.

This International Standard does not include specific information relating to battery sizing,

method of charge or PVES design.
This standard is applicable to all types of secondary batteries.
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 60050 (all parts), International Electrotechnical Vocabulary (IEV) (available at

)

IEC 60622, Secondary cells and batteries containing alkaline or other non-acid electrolytes –

Sealed nickel-cadmium prismatic rechargeable single cells

IEC 60623, Secondary cells and batteries containing alkaline or other non-acid electrolytes –

Vented nickel-cadmium prismatic rechargeable single cells

IEC 60896-11, Stationary lead-acid batteries – Part 11: Vented types – General requirements

and methods of test

IEC 60896-21, Stationary lead-acid batteries – Part 21: Valve regulated types – Methods of

test

IEC 61056-1, General purpose lead-acid batteries (valve-regulated types) – Part 1: General

requirements, functional characteristics – Methods of test
IEC 61836, Solar photovoltaic energy systems – Terms, definitions and symbols

IEC 61951-1, Secondary cells and batteries containing alkaline or other non-acid electrolytes

– Portable sealed rechargeable single cells – Part 1: Nickel-cadmium
---------------------- Page: 12 ----------------------
SIST EN 61427-1:2014
61427-1  IEC:2013 – 7 –

IEC 61951-2, Secondary cells and batteries containing alkaline or other non-acid electrolytes

– Portable sealed rechargeable single cells – Part 2: Nickel-metal hydride

IEC 61960, Secondary cells and batteries containing alkaline or other non-acid electrolytes –

Secondary lithium cells and batteries for portable applications

IEC 62259, Secondary cells and batteries containing alkaline or other non-acid electrolytes –

Nickel-cadmium prismatic secondary single cells with partial gas recombination
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-482

concerning secondary cells and batteries, and those given in IEC 61836 concerning

photovoltaic generator systems apply.
4 Conditions of use
4.1 General

This clause specifies the particular operating conditions experienced by secondary batteries

during their use in photovoltaic applications.
4.2 Photovoltaic energy system

The photovoltaic energy system with secondary batteries referred to in this standard can

supply a constant, variable, or intermittent energy to the connected equipment (pumps,

refrigerators, lighting systems, communication systems, etc.).
4.3 Secondary cells and batteries

Secondary cells and batteries mainly used in photovoltaic energy systems are of the following

types:
a) vented (flooded);
b) valve-regulated, including those with partial gas recombination;
c) gastight sealed.
The cells and batteries are normally delivered in the following state of charge:
d) discharged and drained (vented nickel-cadmium batteries only);
e) charged and filled;
f) dry charged and unfilled (vented lead-acid batteries only);
g) discharged and filled (nickel-cadmium batteries only).

For optimum service life, the battery manufacturer’s instructions for initial charge of the

battery shall be followed.

Other secondary cells and batteries such as based on sodium or vanadium electrochemical

systems can be potentially used for such an application. Due to the fact that they are in a

phase of adaptation for a possible use in PV systems, it is recommended that their respective

supplier be contacted for the necessary planning, test and operation details.
---------------------- Page: 13 ----------------------
SIST EN 61427-1:2014
– 8 – 61427-1  IEC:2013
4.4 General operating conditions
4.4.1 General

Batteries in a typical PV system operating under average site weather conditions may be

subjected to the following conditions.
4.4.2 Autonomy time

The battery is designed to supply energy under specified conditions for a period of time,

typically from 3 days to 15 days without solar irradiation.

When selecting the required battery capacity, the following items should be considered, e.g.:

• required daily/seasonal cycle (there may be restrictions on the maximum depth of

discharge);
• time required to access the site;
• ageing;
• operating temperature;
• future expansion of the load.
4.4.3 Typical charge and discharge currents
The typical charge and discharge currents are the following:
– maximum charge current: I (A)
– average charge current: I (A)
– average discharge current as determined by the load: I (A)
120

Depending on the system design, the charge and the discharge current may vary in a wider

range.

In some systems the load current must be supplied at the same time as the battery charging

current.
NOTE 1 The following abbreviations are used:
• C is the rated capacity declared by the manufacturer in ampere-hours (Ah)
• t is the time base in hours (h) for which the rated capacity is declared
• I = C /t
rt rt
For Nickel Cadmium, Nickel Metal Hydride and Lithium battery systems
• I = C /1h in this document corresponds to I = C /1h
rt rt t 5
4.4.4 Daily cycle
The battery is normally exposed to a daily cycle as follows:
a) charging during daylight hours;
b) discharging during night-time hours.

A typical daily usage results in a discharge between 2 % to 20 % of the battery capacity.

4.4.5 Seasonal cycle

The battery may be exposed to a seasonal cycle of its state of charge. This arises from

varying average-charging conditions as follows:
---------------------- Page: 14 ----------------------
SIST EN 61427-1:2014
61427-1  IEC:2013 – 9 –

• periods with low solar irradiation, for instance during winter causing low energy

production. The state of charge of the battery (available capacity) can go down to 20 % of

the rated capacity or less;

• periods with high solar irradiation, e.g. in summer, which will bring the battery up to the

fully charged condition, with the possibility that the battery could be overcharged.

4.4.6 Period of high state of charge

During summer for example, the battery will be operated at a high state of charge (SOC),

typically between 80 % and 100 % of rated capacity.

A voltage regulator system normally limits the maximum battery voltage during the recharge

period.

NOTE In a "self-regulated" PV system, the battery voltage is not limited by a charge controller but by the

characteristics of the PV generator.

The system designer normally chooses the maximum charge voltage of the battery as a

compromise allowing to recover to a maximum state of charge (SOC) as early as possible in

the summer season but without substantially overcharging the battery.

The overcharge increases the gas production resulting in water consumption in vented cells.

In valve-regulated lead-acid cells, the overcharge will cause less water consumption and gas

emission but more heat generation.

Typically the maximum charge voltage is 2,4 V per cell for lead-acid batteries and 1,55 V per

cell for vented nickel-cadmium batteries at the reference temperature specified by the

manufacturer. Some regulators allow the battery voltage to exceed these values for a short

period as an equalizing or boost charge. For the other batteries the battery manufacturers

shall give the most adapted charge voltage values. Charge voltage compensation shall be

used according to the battery manufacturer instructions if the battery operating temperature

deviates significantly from the reference temperature.

The expected lifetime of a battery in a PV system, even kept regularly at a high state of

charge, may be considerably less than the published life of the battery used under continuous

float charge conditions.
4.4.7 Period of sustained low s
...

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