SIST EN IEC 62933-4-2:2025

SLOVENSKI STANDARD
01-junij-2025
Sistemi za shranjevanje električne energije (EES) - 4-2. del: Smernice o okoljskih
vprašanjih - Ocenjevanje učinkov na okolje pri odpovedi baterije v sistemu, ki
temelji na elektrokemičnem hranilniku (IEC 62933-4-2:2025)
Electric energy storage (EES) systems - Part 4-2: Guidance on environmental issues -
Assessment of the environmental impact of battery failure in an electrochemical based
storage system (IEC 62933-4-2:2025)
Elektrische Energiespeichersysteme (EES) - Bewertung der Umweltauswirkungen eines
Batterieausfalls in einem elektrochemischen Speichersystem (IEC 62933-4-2:2025)
Systèmes de stockage de l’énergie électrique (EES) - Partie 4-2: Recommandations
relatives aux problèmes environnementaux - Évaluation de l’impact environnemental
d’une défaillance de batterie dans un système de stockage d’énergie électrochimique
(IEC 62933-4-2:2025)
Ta slovenski standard je istoveten z: EN IEC 62933-4-2:2025
ICS:
13.020.30 Ocenjevanje vpliva na okolje Environmental impact
assessment
27.010 Prenos energije in toplote na Energy and heat transfer
splošno engineering in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 62933-4-2

NORME EUROPÉENNE
EUROPÄISCHE NORM April 2025
ICS 13.020.30; 27.010
English Version
Electric energy storage (EES) systems - Part 4-2: Guidance on
environmental issues - Assessment of the environmental impact
of battery failure in an electrochemical based storage system
(IEC 62933-4-2:2025)
Systèmes de stockage de l'énergie électrique (EES) - Partie Elektrische Energiespeichersysteme (EES) - Bewertung der
4-2: Recommandations relatives aux problèmes Umweltauswirkungen eines Batterieausfalls in einem
environnementaux - Évaluation de l'impact environnemental elektrochemischen Speichersystem
d'une défaillance de batterie dans un système de stockage (IEC 62933-4-2:2025)
d'énergie électrochimique
(IEC 62933-4-2:2025)
This European Standard was approved by CENELEC on 2025-04-04. 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.
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Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62933-4-2:2025 E

European foreword
The text of document 120/387/FDIS, future edition 1 of IEC 62933-4-2, prepared by TC 120 "Electrical
Energy Storage (EES) systems" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 62933-4-2:2025.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2026-04-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2028-04-30
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 62933-4-2:2025 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60896-21:2004 NOTE Approved as EN 60896-21:2004 (not modified)
IEC 60896-22:2004 NOTE Approved as EN 60896-22:2004 (not modified)
IEC 61427-1:2013 NOTE Approved as EN 61427-1:2013 (not modified)
IEC 61427-2:2015 NOTE Approved as EN 61427-2:2015 (not modified)
IEC 62485-2:2010 NOTE Approved as EN IEC 62485-2:2018 (not modified)
IEC 62485-3:2014 NOTE Approved as EN 62485-3:2014 (not modified)
IEC 62485-5:2020 NOTE Approved as EN IEC 62485-5:2021 (not modified)
IEC 62619:2022 NOTE Approved as EN IEC 62619:2022 (not modified)
IEC 62620:2014 NOTE Approved as EN 62620:2015 (not modified)
IEC 62675:2014 NOTE Approved as EN 62675:2014 (not modified)
IEC 62932-1:2020 NOTE Approved as EN IEC 62932-1:2020 (not modified)
IEC 62932-2-1:2020 NOTE Approved as EN IEC 62932-2-1:2020 (not modified)
IEC 62933 series NOTE Approved as EN IEC 62933 series
IEC 62933-1:2024 NOTE Approved as EN IEC 62933-1:2024 (not modified)
IEC 62933-5-2:2020 NOTE Approved as EN IEC 62933-5-2:2020 (not modified)
IEC 62984-1:2020 NOTE Approved as EN IEC 62984-1:2020 (not modified)
IEC 62984-2:2020 NOTE Approved as EN IEC 62984-2:2020 (not modified)
IEC 62984-3:2020 NOTE Approved as EN IEC 62984-3:2020 (not modified)
IEC 63056:2020 NOTE Approved as EN IEC 63056:2020 (not modified)
IEC 63115-1:2020 NOTE Approved as EN IEC 63115-1:2020 (not modified)
IEC 63115-2:2021 NOTE Approved as EN IEC 63115-2:2021 (not modified)

IEC 62933-4-2 ®
Edition 1.0 2025-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electric energy storage (EES) systems –

Part 4-2: Guidance on environmental issues – Assessment of the environmental

impact of battery failure in an electrochemical based storage system

Systèmes de stockage de l’énergie électrique (EES) –

Partie 4-2: Recommandations relatives aux problèmes environnementaux –

Évaluation de l’impact environnemental d’une défaillance de batterie dans un

système de stockage d’énergie électrochimique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.020.30, 27.010 ISBN 978-2-8327-0147-8

– 2 – IEC 62933-4-2:2025 © IEC 2025
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references. 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms . 8
4 General . 8
5 Failure of the electrochemical accumulation system in a BESS resulting in
environmental issues . 8
5.1 General . 8
5.2 View of the subsystem structure in a BESS and the battery-related failure
site . 9
5.3 Classification of BESS types . 9
5.4 Failure of batteries in the electrochemical accumulation subsystem of a
BESS . 10
6 Guidelines for assessing the environmental impact of a failure of the battery of the
electrochemical accumulation subsystem of the BESS . 11
6.1 General . 11
6.2 Root causes of battery and flow battery failures resulting in impact on the
environment . 11
6.2.1 General . 11
6.2.2 Root causes resulting in battery and flow battery failures . 12
6.2.3 Environmental impacts upon disassembly and disposal of a failed
battery . 14
6.3 Reporting the assessment . 14
Annex A (informative) Summary of typical properties of commercially available
electrochemical energy storage systems for BESS installations . 16
Annex B (informative) Potential environmental impacts related to the type of battery
in the BESS . 22
B.1 General . 22
B.2 Cells with non-aqueous electrolyte – C-A type . 22
B.3 Cells with aqueous electrolyte – C-B type . 22
B.4 Cells with solid electrolyte and operating at temperatures above 250 °C –C-
C type . 23
B.5 Cells with aqueous but recirculating electrolyte or flow cells – C-D type . 23
B.6 Cells with any other electrochemical couple, electrolyte and energy storage
concept or combinations thereof – C-Z type . 23
B.7 Environmental impacts upon disassembly and disposal of a failed battery . 23
Annex C (informative) Selected BESS application scenarios . 24
Annex D (informative) Description of batteries used in BESS . 25
D.1 General . 25
D.2 Cells with non-aqueous electrolyte – C-A type . 25
D.3 Cells with aqueous electrolyte – C-B type . 26
D.4 Cells with solid electrolyte operating at temperatures above 250 °C –
C-C type . 26
D.5 Cells with aqueous but recirculating electrolyte or flow cells – C-D type . 27
D.6 Cells with any other electrochemical couple, electrolyte and energy storage
concept or combinations thereof – C-Z type . 27

IEC 62933-4-2:2025 © IEC 2025 – 3 –
Bibliography . 28

Figure 1 – Example of a BESS structure . 9
Figure 2 – Failure sites in the electrochemical accumulation subsystem within the
scope of this document (highlighted in grey) . 10
Figure 3 – Proximate root causes leading to a battery or flow battery failure in the
BESS with associated environmental impacts . 12
Figure C.1 – BESS application scenarios. 24

Table 1 – Classification of BESS types . 10
Table 2 – Excerpt of a possible assessment report describing failures of a specific
battery and the resulting environmental impacts . 15
Table A.1 – Summary list of typical properties of commercially available
electrochemical energy storage systems in BESS installations – Part 1 . 17

– 4 – IEC 62933-4-2:2025 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –

Part 4-2: Guidance on environmental issues –
Assessment of the environmental impact of battery
failure in an electrochemical based storage system

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
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 62933-4-2 has been prepared by IEC technical committee 120: Electrical Energy Storage
(EES) Systems. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
120/387/FDIS 120/403/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
IEC 62933-4-2:2025 © IEC 2025 – 5 –
The language used for the development of this International Standard is English.
A list of all parts in the IEC 62933 series, published under the general title Electrical energy
storage (EES) systems, can be found on the IEC website.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
– 6 – IEC 62933-4-2:2025 © IEC 2025
ELECTRICAL ENERGY STORAGE (EES) SYSTEMS –

Part 4-2: Guidance on environmental issues –
Assessment of the environmental impact of battery
failure in an electrochemical based storage system

1 Scope
This part of IEC 62933 defines the requirements for evaluating and reporting the negative
impact on the environment caused by the failure of a cell, flow cell, battery or flow battery in
the accumulation subsystem of a battery energy storage system (BESS).
The batteries within this scope used in a BESS are classified according to the type of their
electrolyte. These electrolyte types are aqueous, non-aqueous or solid.
The environmental impacts directly caused by the failure of other components of the BESS are
not within the scope of this document.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
cell
basic functional unit, consisting of an assembly of electrodes, electrolyte, container, terminals
and usually separators, that is a source of electric energy obtained by direct conversion of
chemical energy
[SOURCE: IEC 60050-482:2004, 482-01-01, modified – the Note has been deleted.]
3.1.2
flow cell
secondary cell characterized by the spatial separation of the electrodes and the movement of
the energy storage fluids
[SOURCE: IEC 62932-1:2020, 3.1.14, modified – the Note has been deleted.]

IEC 62933-4-2:2025 © IEC 2025 – 7 –
3.1.3
flow battery
two or more flow cells electrically connected including all components for use in an
electrochemical energy storage system
3.1.4
battery
one or more cells fitted with devices necessary for use, for example case, terminals, marking
and protective devices
[SOURCE: IEC 60050-482:2004, 482-01-04]
3.1.5
battery system
assembly of batteries or flow batteries installed on racks or in cabinets with associated
electrical, electromechanical, environmental control components and ready to operate
3.1.6
battery management system
BMS
electronic system associated with a battery which has functions to control current in case of
overcharge, overcurrent, overdischarge and overheating and which monitors and/or manages
the battery's state, calculates secondary data, reports that data and/or controls its environment
to influence the battery's safety, performance and/or service life
[SOURCE: IEC 62619:2022, 3.12, modified – the Notes have been deleted.]
3.1.7
failure
loss of ability of the cell, flow cell, battery or flow battery to perform as required
Note 1 to entry: This failure results in a fault of the accumulation subsystem and by derivation, of the BESS.
[SOURCE IEC 60050-192:2015, 192-03-01, modified – replaced "item" with "the cell, flow cell,
battery or flow battery", notes have been deleted and added new Note 1.]
3.1.8
failure cause
set of circumstances that leads to failure
Note 1 to entry: A failure cause can originate during specification, design, manufacture, transportation, installation,
operation or maintenance of an item
[SOURCE: IEC 60050-192:2015, 192-03-11]
3.1.9
environment
natural and man-made surroundings in which an EES system is installed, operates and
interacts, including buildings and facilities, air, water, land, natural resources, flora, fauna
(including human inhabitants) of those surroundings
[SOURCE: IEC 60050-904:2014, 904-01-01, modified – expansion of the scope to include man-
made surroundings, dynamic interactions, and specific EES system contexts.]
3.1.10
system integrator
entity that specializes in planning, coordinating, building, implementing and testing of systems

– 8 – IEC 62933-4-2:2025 © IEC 2025
3.1.11
manufacturer
entity that produces the specified item and owns the manufacturing process by which it was
created
3.2 Abbreviated terms
BESS battery energy storage system
BMS battery management system
EES electrical energy storage
HVAC heating, ventilation and air conditioning
LFP lithium iron phosphate
LTO lithium titanium oxide
MSDS material safety data sheet
NCA nickel cobalt aluminium oxide
NMC nickel manganese cobalt oxide
PCS power conversion system
POC point of connection
SDS safety data sheet
SOC state of charge
SOH state of health
VRLA valve regulated lead acid
4 General
The environmental impact of a battery failure depends on the battery type, design and structures.
This document provides guidance and requirements on how to identify the potential impacts on
the environment when the battery of an electrochemical energy accumulation system fails.
The operation, under conditions licensed by the local authorities, of the BESS including its
batteries and flow batteries, is considered to occur without any negative environmental impact.
5 Failure of the electrochemical accumulation system in a BESS resulting in
environmental issues
5.1 General
A failure is defined in this document as a loss of ability of the cell, flow cell, battery or flow
battery in the electrochemical accumulation subsystem to perform as required. This failure
results in a fault of the accumulation subsystem and, by derivation, can result also in a failure
of the BESS with possibly environmental issues.
For the present document, those failure-inducing causes are considered if the subsequent
failure(s) of the cell, flow cell, battery or flow battery in the electrochemical accumulation
subsystem negatively impact(s) the environment surrounding the BESS.

IEC 62933-4-2:2025 © IEC 2025 – 9 –
The failure causes to be considered in this document are the result of:
1) electrochemical accumulation subsystem internal causes such as a fault developing due to
weakness of materials or of an assembly or divergent chemical or electrochemical reactions;
or
2) electrochemical accumulation subsystem external causes such as a fault developing due to
a failure of ancillary equipment, unfavourable environmental conditions or loss of essential
parameters, data and functions needed for safe operation.
Failures of other subsystems of the BESS are not assessed within this document for their direct
negative impact on the environment.
5.2 View of the subsystem structure in a BESS and the battery-related failure site
The typical subsystems architecture of a BESS is shown in Figure 1 with the location of the
battery highlighted
NOTE The location of the electrochemical accumulation subsystem and its battery are highlighted in the dark grey
box.
Figure 1 – Example of a BESS structure
5.3 Classification of BESS types
The BESS types are categorized in Table 1, according to IEC 62933-5-2, into five types based
on the specific features of the installed electrochemical storage system, i.e. the installed battery
type and its electrolyte.
– 10 – IEC 62933-4-2:2025 © IEC 2025
Table 1 – Classification of BESS types
BESS type designation Distinguishing design features
Cell with non-aqueous electrolyte
C-A
(e.g., Li-ion)
Cell with aqueous electrolyte
C-B
(e.g., Pb acid, NiMH)
Cell with solid electrolyte and operating above 250 °C or defined as HT (high
temperature) cell
C-C
(e.g., NaS, NaNiCl)
Cell with aqueous but recirculating electrolyte or defined as flow cell
C-D
(e.g., V5+/V2+)
Cell with any other electrochemical couple, electrolyte and energy storage concept
or combinations thereof
C-Z
(e.g., Li metal with solid electrolyte, electrochemical double layer capacitors)

The classification of the battery types used in a BESS and listed in Table 1 is subject to
evolutions as advances in battery technology bring changes in electrolytes and cell designs.
The attributes of a BESS type designation, based on the installed battery and reported in the
environmental impact assessment document, are only informative in nature. They do not
release the system integrator and battery manufacturer carrying out the environmental impact
assessment of a battery failure according to this document, from considering all features of the
battery or flow battery of the BESS at hand.
5.4 Failure of batteries in the electrochemical accumulation subsystem of a BESS
The failure sites in the electrochemical accumulation subsystem in this document are
highlighted in Figure 2.
Figure 2 – Failure sites in the electrochemical accumulation subsystem
within the scope of this document (highlighted in grey)

IEC 62933-4-2:2025 © IEC 2025 – 11 –
6 Guidelines for assessing the environmental impact of a failure of the battery
of the electrochemical accumulation subsystem of the BESS
6.1 General
Batteries and flow batteries are equipment containing reactive metals and chemicals and are
also sources of uninterruptable flows of electrical energy. These components and effects can
be released into the environment in an uncontrolled fashion when the battery or flow battery in
the accumulation subsystem fails.
The system integrator of the BESS, therefore, carries out, in collaboration with the
electrochemical accumulation subsystem, a systematic assessment of when and how wear-out,
ageing, deterioration, damage, non-compliance, environmental factors, flawed operation(s) or
outright failure(s) of a constituent of the BESS result in failures of the electrochemical
accumulation subsystem with a subsequent impact on the environment.
To ensure a structured assessment of the failures, an overview of the cell designs is presented
in Annex D. This is followed in Annex B by an overview of the environmental impacts resulting,
upon a failure, from the battery and flow battery materials, their reactions and associated
disruptive electric effects.
In 6.2 a structured set of root causes of such failures is presented. These root causes reflect
the multiple origins of a failure of the battery or flow battery in a BESS and are applicable to
the designs C-A to C-Z, respectively.
6.2 Root causes of battery and flow battery failures resulting in impact on the
environment
6.2.1 General
Internal and external causes that can result in a failure of the cell, flow cell, battery or flow
battery and possibly have an impact on the environment, are reviewed and enumerated below.
Potential failures are systematically listed below, which are further the result of root causes
depicted in Figure 3.
• Performance degradation
– inability to deliver rated energy (cause 1)
– inability to accept rated energy (cause 2)
• System degradation
– failed structural integrity (cause 3)
– failed system integrity (cause 4)
• Subsystems degradation
– failed accessory components (cause 5)
– failed control subsystem (cause 8)
– failed auxiliary subsystem (cause 9)
• Unexpected inputs from the POC/interface
– failed environmental controls (cause 6)
– failed electric integrity (cause 7)
• Unexpected external environment impacts to the system
– environmental impacts (cause 10)

– 12 – IEC 62933-4-2:2025 © IEC 2025
A schematic view of key proximate (immediate) root causes leading to failures is shown in
Figure 3.
Figure 3 – Proximate root causes leading to a battery or flow battery failure
in the BESS with associated environmental impacts
6.2.2 Root causes resulting in battery and flow battery failures
6.2.2.1 General
The assessment of the failures and their environmental impacts shall be carried out on the
battery and its layout by the system integrator in collaboration with the battery or flow battery
manufacturer. Local regulations can apply and can designate any other entity to perform the
assessment.
This assessment shall be made available, in an appropriate format and detail, to the interested
parties such as the BESS operator, licensing authorities, environmental protection agencies or
other relevant entities for follow-up actions as needed. Local regulations can apply.
The assessment activity starts from the relevant proximate, i.e. close-by root cause(s), and
details their resulting impacts on the cells, flow cell, battery and flow battery.
These impacts can lead to their failure resulting in a fault of the BESS.

IEC 62933-4-2:2025 © IEC 2025 – 13 –
The failure causes of the cell, flow cell, battery, or flow battery are evaluated with due diligence
for their potential impact on the environment, as relev
...