IEC 60364-5-57:2022

Low-voltage electrical installations - Part 5-57: Selection and erection of electrical equipment - Erection of stationary secondary batteries

IEC 60364-5-57:2022 provides requirements and recommendations for the design, erection, correct use and protection of installations with secondary stationary batteries as prime storage medium, hereinafter referred to as "stationary secondary batteries".
This document is not applicable to products such as batteries and to systems design (including batteries) which are already covered by their own IEC standard.

Installations électriques à basse tension - Partie 5-57: Choix et mise en œuvre des matériels électriques - Mise en œuvre des batteries d’accumulateurs stationnaires

IEC 60364-5-57:2022 fournit des exigences et recommandations pour la conception, la mise en œuvre, la bonne utilisation et la protection des installations dont les principaux dispositifs accumulateurs sont des batteries stationnaires d’accumulateurs, appelées ci-après “batteries d’accumulateurs stationnaires”.
Le présent document n’est pas applicable aux produits tels que les batteries et à la conception des systèmes (y compris les batteries) qui sont déjà couverts par leur propre norme IEC.

General Information

• Status: Published
• Publication Date: 19-Oct-2022
• ICS: 31.220.01 - Electromechanical components in general
• ICS: 91.140.50 - Electricity supply systems
• Technical Committee: TC 64 - Electrical installations and protection against electric shock
• Drafting Committee: PT 60364-5-57 - TC 64/PT 60364-5-57
• Current Stage: PPUB - Publication issued
• Start Date: 20-Oct-2022
• Completion Date: 29-Jul-2022

Overview

IEC 60364-5-57:2022 is an international standard published by the International Electrotechnical Commission (IEC) that specifies key requirements and recommendations for the selection, erection, and safe installation of stationary secondary batteries in low-voltage electrical installations. Stationary secondary batteries refer to rechargeable batteries used as prime energy storage mediums for backup power or other stationary applications. This standard focuses on the design, correct use, and protection measures necessary for these battery installations.

Importantly, IEC 60364-5-57:2022 does not cover the design or testing of battery products themselves, nor whole system designs that include batteries, which are addressed in separate IEC standards.

Key Topics

• Scope and Application
  The standard applies specifically to secondary stationary batteries within low-voltage electrical installations, outlining safety and performance requirements for their erection and use.

• Operation Modes
  It details operation scenarios such as grid-connected mode and islanding mode, crucial for applications where batteries support or isolate from the electrical grid.

• Characteristics of Stationary Secondary Batteries
  Includes guidance on battery types, selection criteria, and integration with electrical converters to optimize performance and safety.

• Protection Measures
  Addresses comprehensive safety considerations including:

  • Protection against electric shock
  • Thermal effect prevention to avoid overheating
  • Protection against short-circuits
  • Effective isolation methods
  • Countermeasures for unexpected islanding events
  • Additional safeguards against miscellaneous hazards associated with battery installations

• Battery Accommodation
  Instructions for battery room design to ensure safe housing, including ventilation, separation zones, and warning labels.

• Technical Appendices
  Informative annexes provide detailed technical data such as discharge characteristics, internal impedance, gas evolution phenomena, and effects of load on battery behavior.

Applications

IEC 60364-5-57:2022 serves as a critical reference for engineers, designers, and electrical installation professionals involved in:

• Installing stationary backup power systems using lead-acid, nickel-cadmium, or other rechargeable battery technologies
• Designing emergency power supplies in commercial or industrial environments
• Implementing energy storage solutions that interface with electrical grids, including microgrids and islanded systems
• Ensuring compliance with international safety standards to mitigate risks related to electric shock, fire, and environmental hazards in battery rooms
• Supporting prosumers and low-voltage installations that incorporate battery energy storage for reliability and resilience

Related Standards

Users should consider IEC 60364-5-57:2022 alongside related IEC standards to ensure comprehensive compliance and safety:

• IEC 60364-4-41 – Protection against electric shock in low-voltage installations
• IEC 60364-5-53 – Selection and erection of safety and isolation devices
• IEC 60364-5-54 – Earthing arrangements and protective conductors
• IEC 60364-8-82 – Prosumer low-voltage electrical installations involving battery storage
• IEC 60896-21 – Test methods for valve-regulated stationary lead-acid batteries
• IEC 61340-4-1 – Standard test methods addressing electrostatics relevant to battery installations

By integrating the requirements of IEC 60364-5-57:2022 with these complementary standards, electrical professionals can ensure the safe and effective deployment of stationary secondary batteries in low-voltage systems.

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Keywords: stationary secondary batteries, IEC 60364-5-57:2022, low-voltage electrical installations, battery erection standard, secondary battery protection, electrical safety, battery room requirements, battery backup systems, low-voltage battery installations, IEC battery installation standards.

Standards Content (Sample)

IEC 60364-5-57 ®
Edition 1.0 2022-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low voltage electrical installations –
Part 5-57: Selection and erection of electrical equipment – Erection of
stationary secondary batteries
Installations électriques à basse tension –
Partie 5-57: Choix et mise en œuvre des matériels électriques – Mise en œuvre
des batteries d’accumulateurs stationnaires
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IEC 60364-5-57 ®
Edition 1.0 2022-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low voltage electrical installations –
Part 5-57: Selection and erection of electrical equipment – Erection of
stationary secondary batteries
Installations électriques à basse tension –
Partie 5-57: Choix et mise en œuvre des matériels électriques – Mise en œuvre
des batteries d’accumulateurs stationnaires
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 91.140.50 ISBN 978-2-8322-3941-4
– 2 – IEC 60364-5-57:2022 © IEC 2022
CONTENTS
FOREWORD . 4
570.1 Scope . 6
570.2 Normative references . 6
570.3 Terms and definitions . 7
570.4 Operation modes . 8
570.4.1 Grid connected . 8
570.4.2 Grid connected and islanding mode . 9
570.5 Main characteristics of stationary secondary batteries . 9
570.5.1 Types of equipment . 9
570.5.2 Selection of battery . 10
570.5.3 Converter . 10
570.6 Selection and erection of electrical equipment . 10
570.6.1 General . 10
570.6.2 Measures for protection against electric shock. 11
570.6.3 Protection against thermal effects . 12
570.6.4 Protection against short-circuit . 12
570.6.5 Isolation . 13
570.6.6 Unexpected islanding . 13
570.6.7 Protection against other hazards . 14
Annex A (informative) Technical characteristics . 15
A.1 Nominal voltage . 15
A.2 Discharge . 15
A.2.1 Discharge voltage curve . 15
A.2.2 Temperature dependence . 16
A.3 Internal Impedance . 16
A.3.1 General . 16
A.3.2 Battery equivalent circuit . 16
A.3.3 Voltage drop . 17
A.3.4 Thermal effects . 17
A.3.5 Time dependence . 17
A.3.6 Gas evolution of lead acid, nickel-cadmium batteries and zinc dibromide
aqueous electrolyte . 18
Annex B (informative) Technical characteristics for battery load . 19
B.1 C-rate . 19
B.2 Battery discharge performance . 19
B.3 Ripple effects . 20
Annex C (normative) Battery accommodation . 21
C.1 General . 21
C.2 Specific requirements for separate battery rooms . 21
C.3 Specific requirements for the specially separated areas in rooms
accommodating electrical equipment. 22
C.4 Accommodation for lead acid and NiCd batteries in the same room . 22
C.5 Detection means . 22
Annex D (informative) Identification labels and warning notices . 23
Annex E (informative) List of notes concerning certain countries . 24
Bibliography . 25

Figure 1 – Battery operating only when grid connected . 9
Figure 2 – Battery operation with the grid and in island mode . 9
Figure 3 – Battery charger contribution to a DC system fault . 13
Figure A.1 – Examples of cell discharge characteristics for different technologies and
for constant current discharge . 16
Figure A.2 – Battery equivalent circuit impedance . 17
Figure B.1 – Typical discharge curves of lead acid as a function of C-rate as a

parameter . 19
Figure B.2 – Capacity characteristic as a function of discharge time . 20

Table 1 – Protective measures where converter without galvanic separation is used. 12

– 4 – IEC 60364-5-57:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW VOLTAGE ELECTRICAL INSTALLATIONS –

Part 5-57: Selection and erection of electrical equipment –
Erection of stationary secondary batteries

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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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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.
IEC 60364-5-57 has been prepared by IEC technical committee 64: Electrical installations and
protection against electric shock. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
64/2558/FDIS 64/2561/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

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
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The reader's attention is drawn to the fact that Annex E lists all of the "in-some-country"
clauses on differing practices of a less permanent nature relating to the subject of this
document.
A list of all parts in the IEC 60364 series, published under the general title Low voltage
electrical installations, 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 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.
IMPORTANT – The "colour inside" logo on the cover page of this document 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 60364-5-57:2022 © IEC 2022
LOW VOLTAGE ELECTRICAL INSTALLATIONS –

Part 5-57: Selection and erection of electrical equipment –
Erection of stationary secondary batteries

570.1 Scope
This part of IEC 60364 provides requirements and recommendations for the design, erection,
correct use and protection of installations with secondary stationary batteries as prime
storage medium, hereinafter referred to as "stationary secondary batteries".
This document is not applicable to products such as batteries and to systems design
(including batteries) which are already covered by their own IEC standard.
570.2 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 60364-4-41, Low-voltage electrical installations – Part 4-41: Protection for safety –
Protection against electric shock
IEC 60364-5-53:2019, Low-voltage electrical installations – Part 5-53: Selection and erection
of electrical equipment – Devices for protection for safety, isolation, switching, control and
monitoring
IEC 60364-5-54, Low-voltage electrical installations – Part 5-54: Selection and erection of
electrical equipment – Earthing arrangements and protective conductors
IEC 60364-8-82, Low-voltage electrical installations – Part 8-2: Prosumer's low-voltage
electrical installations
IEC 60896-21, Stationary lead-acid batteries – Part 21: Valve regulated types – Methods of
test
IEC 61340-4-1, Electrostatics – Part 4-1: Standard test methods for specific applications –
Electrical resistance of floor coverings and installed floors
IEC 61660-1, Short-circuit currents in d.c. auxiliary installations in power plants and
substations – Part 1: Calculation of short-circuit currents
IEC 61660-2, Short-circuit currents in d.c. auxiliary installations in power plants and
substations – Part 2: Calculation of effects
IEC 62485-2, Safety requirements for secondary batteries and battery installation – Part 2:
Stationary batteries
IEC 62619:2017, Secondary cells and batteries containing alkaline or other non-acid
electrolytes – Safety requirements for secondary lithium cells and batteries, for use in
industrial applications
570.3 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 http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
570.3.1
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 – Note deleted.]
570.3.2
capacity
quantity of electricity (electric charge) which a fully charged cell or
battery can deliver under specified conditions
Note 1 to entry: Capacity is usually expressed in ampere hour (Ah) or watt hour (Wh).
[SOURCE: IEC 60050-482:2020, 482-03-14, modified – "quantity of electricity" and "fully
charged" added, "discharge" deleted and Note 1 to entry replaced with a new Note 1 to entry.]
570.3.3
secondary cell
cell which 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]
570.3.4
secondary battery
assembly of secondary cell(s) ready for use as a source of electrical energy characterized by
its voltage, size, terminal arrangement, capacity and rate capability
[SOURCE: IEC 62133-1:2017, 3.8, modified – Note deleted.]
570.3.5
stationary secondary battery
secondary battery that is permanently connected to the DC power supply and which is
designed for service in a fixed location and is not habitually moved from place to place during
operation
570.3.6
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]

– 8 – IEC 60364-5-57:2022 © IEC 2022
570.3.7
vented cell
secondary cell having a cover provided with an opening through which products of electrolysis
and evaporation are allowed to escape freely from the cell to the atmosphere
[SOURCE: IEC 60050-482:2004, 482-05-14]
570.3.8
valve regulated lead acid battery
VRLA
secondary battery in which cells are closed but have a valve which allows the escape of gas if
the internal pressure exceeds a predetermined value
Note 1 to entry: The cell or battery cannot normally receive additions to the electrolyte.
[SOURCE: IEC 60050-482:2004, 482-05-15]
570.3.9
converter
device for changing one or more characteristics associated with electrical energy
Note 1 to entry: Characteristics associated with electrical energy are for example voltage, number of phases and
frequency including zero frequency.
[SOURCE: IEC 60050-151:2001, 151-13-36, modified – "electric" replaced with "electrical"
and in the note "electrical" added to "energy".]
570.3.10
island mode
operating mode in which the prosumer’s electrical installation (PEI) is disconnected from the
distribution network
570.3.11
System referencing conductor
conductor connecting one live conductor of the power system and an earthing arrangement
Note 1 to entry: The live conductor connected is the neutral or the mid-point if existing, or a line conductor when
not existing.
570.4 Operation modes
570.4.1 Grid connected
The battery is permanently connected to the grid.
In case of outage of the grid, the battery shall be automatically disconnected from the
installation. See Figure 1.
Figure 1 – Battery operating only when grid connected
570.4.2 Grid connected and islanding mode
In islanding mode, the battery supplies the installation even when the grid is disconnected
from the installation. See Figure 2.

Figure 2 – Battery operation with the grid and in island mode
570.5 Main characteristics of stationary secondary batteries
570.5.1 Types of equipment
Stationary secondary batteries are defined by their physical construction. They shall be
designed to be fixed installed and fixed connected to an electrical installation.
Various types of secondary cells, defined by their chemical composition, can be used.
EXAMPLE
a) lead acid;
b) nickel;
– nickel-cadmium (NiCd);
– nickel-metal-hydride (NiMH);
c) lithium-ion (Li-ion);
– lithium cobalt oxide (LiCoO2);
– lithium manganese oxide (LiMn2O4);
– lithium iron phosphate (LiFePO4);
– lithium nickel manganese cobalt oxide (LiNiMnCoO2);
– lithium nickel cobalt aluminium oxide (LiNiCoAlO2);
– lithium titanate (Li4Ti5O12);
– lithium ion polymer (LiPo);
d) zinc dibromide aqueous electrolyte.

– 10 – IEC 60364-5-57:2022 © IEC 2022
570.5.2 Selection of battery
The selection of capacity and battery types depends on many parameters such as:
• load characteristics;
• battery voltage;
• usable battery capacity;
• charge time and discharge time;
• converter connection.
The required usable capacity of batteries shall be estimated according to the following
formulas:
Load power (W ) x Running time(h)
{ } { }
Capacity (Ah) =
Battery voltage V
( )
Capacity (Wk) = {Load power (W)} × {Running time (h)}
NOTE 1 Usable battery capacity can also depend on the ambient temperature and number of charging cycles.
NOTE 2 See Annex A for technical characteristics of secondary cells that can be relevant for the erection of
stationary secondary batteries.
570.5.3 Converter
The type of converter shall be selected to be suitable for the type of battery and its
application.
NOTE See Annex B for technical characteristics for battery load.
The AC voltage ripple shall be kept within the range specified by the battery manufacturer
(see also Clause B.3).
Protective provisions and DC safety instructions shall be provided.
570.6 Selection and erection of electrical equipment
570.6.1 General
570.6.1.1 Main principle
A battery shall be considered as both supply and load. Therefore, energy can flow in both
directions and safety devices shall be chosen accordingly.
The voltage at the battery terminals shall be assumed to be always present, therefore all
safety precautions shall be taken considering this fact.
In general, battery protection shall address the following undesirable events or conditions, as
applicable:
– excessive current during charging or discharging;
– short-circuit;
– overvoltage;
– overcharging;
– undervoltage – exceeding preset depth of discharge (DoD) limits;

– extreme ambient temperatures (see A.2.2);
– overheating – exceeding a cell temperature limit;
– pressure build-up inside the cell;
– automatic disconnection of the battery from the connected system in case of an
emergency.
Some batteries can include built-in protective devices which can provide several layers of
additional protection.
EXAMPLE Lithium-ion battery built-in protection can include:
– excess of temperature;
– short-circuit current.
In all cases manufacture's instructions shall be complied with.
For Li-ion batteries the following risks shall be considered:
a) Faults which can be avoided by suitable monitoring of each cell for current (charge current
is temperature dependent), voltage and temperature (U, I, T). If one or more cells were
outside of one of their operating limits, they shall be considered as damaged and should
not continue to operate.
b) Cell internal problems (short-circuits by dendrites, gassing, material degradation). These
risks can be reduced by the selection of cells regarding quality and homogeneity. Refer
also to IEC 62619:2017, 7.3. (internal short-circuits) and 7.3.3 (propagation test). Single
cell defects can propagate by affecting other Li-ion cells nearby and can cause a slow
chain reaction. The cells should be placed or separated in a way which avoids
propagation.
For an erected battery made from Li-ion cells, the same safety requirements as for complete
battery products shall at least comply with the requirements of IEC 62619.
Batteries intended for use by other than skilled or instructed persons shall be installed within
enclosures which shall only be opened by a key or tools. See Annex C.
570.6.1.2 Protective earthing
Where an earthing arrangement is connected on the DC side of the converter, the converter
shall have a galvanic separation.
To prevent circulating currents, the system shall be earthed at one point only.
Where the battery system is designed to be used in islanding mode, the earthing of the
battery system during the island mode shall be designed in accordance with IEC 60364-8-82
and IEC 60364-5-54.
Where earthing is provided on the DC side, measures shall be taken to prevent the risk of
electrolytic corrosion due to DC currents.
570.6.2 Measures for protection against electric shock
570.6.2.1 General
Where the protective measure consists in the automatic disconnection of supply or of the
PELV system, battery racks or battery cabinets made from conductive material shall be
connected to the protective conductor. Otherwise the battery racks or battery cabinet shall be
insulated from the battery and its place of installation.

– 12 – IEC 60364-5-57:2022 © IEC 2022
Where batteries are installed in a dedicated room, the room shall be only accessible to
instructed persons (BA4) or skilled persons (BA5) and a supplementary equipotential bonding
shall be provided.
Where batteries are installed in a dedicated enclosure, the enclosure shall be only accessible
by use of a key or tool.
570.6.2.2 Automatic disconnection of the supply
570.6.2.2.1 Converter without galvanic separation
Protection against electric shock shall be provided according to Table 1.
Table 1 – Protective measures where converter without galvanic separation is used
TN – TT systems IT system
Grid RCD type B at the origin of the Automatic disconnection of supply
connected dedicated circuit connected to the at the origin of the dedicated
battery circuit connected to the battery
is required at the first fault
Island RCD type B on the AC side of the Automatic disconnection of supply
mode converter and a RCD on the at the origin of the dedicated
dedicated circuit connected to the circuit connected to the battery
battery system system is required at the first
fault
570.6.2.2.2 Converter with galvanic separation
In TT and TN systems, the converter shall be switched off on the DC side at the first fault and
the System referencing conductor shall be switched off.
In IT systems, the converter shall be switched off on the DC side at the first fault.
570.6.2.3 Electrical separation
An electrical separation shall not be used.
570.6.2.4 SELV system or PELV system
Where the protective measure is a SELV system or a PELV system, the battery assembly and
the converter shall comply with the requirements relating to the source for the SELV system
and the PELV system.
570.6.3 Protection against thermal effects
The location or enclosure of fixed stationary secondary batteries shall be adequately
ventilated in accordance with the manufacturer’s instructions.
Electrical equipment liable to generate sparks, arcs or flames shall be installed at a safe
distance from battery types that are able to produce gases.
570.6.4 Protection against short-circuit
570.6.4.1 Short-circuit current
Calculation of the battery short-circuit current reference shall be made in accordance with
IEC 61660-1 and IEC 61660-2 as well as IEC 60896-21.

570.6.4.2 Battery contribution
As a battery will operate as a continuous power source until the end of its discharge voltage is
reached, it could be considered that the power delivered by the battery remains constant in all
circumstances. However, the current will increase as the battery voltage declines during
usage, or until the battery reaches the end of its discharge voltage lower limit. During
abnormal conditions such as short-circuit, the current will be limited by the internal impedance
of the battery and the inductance of the cable runs attached to the terminal.
570.6.4.3 Battery charger contribution
Estimation of the short-circuit current shall also consider the contribution of the battery
charger. The charger output capacitances can generate a short spike for a few microseconds,
then until the current limiting takes effect a few milliseconds later, the charger contribution to
the short-circuit current will be limited by its internal resistance. Afterwards, the charger
provides its current limit rating (see Figure 3).

Figure 3 – Battery charger contribution to a DC system fault
570.6.5 Isolation
A battery system can be supplied by multiple sources. A battery system is considered as a
source of supply. Every feeder connected to the battery system as an input and/or output
shall be provided with a means of isolation in compliance with IEC 60364-5-53:2019, 536.2.
570.6.6 Unexpected islanding
Unexpected islanding shall be considered during the design of the installation.

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570.6.7 Protection against other hazards
The location or enclosure of fixed stationary secondary batteries shall provide measures of
protection in accordance with the battery manufacturer’s instructions to mitigate the following:
– risk of explosion;
– safety distances;
– unsuitable conditions arising by remote control;
– working space;
– egress and protection from physical hazards.
NOTE 1 See IEC TS 62933-5-1, IEC 62485-2 and IEC 62933-5-2.
NOTE 2 See Annex D for Identification labels and warning notices.

Annex A
(informative)
Technical characteristics
A.1 Nominal voltage
Nominal voltages for each type of secondary cell follow an agreed convention as follows:
– Lead acid: The nominal voltage of a cell of lead acid is fixed at 2,00 V. The open circuit
voltage (OCV) for a fully charged lead acid cell is normally in the range between 2,05 V to
2,15 V per cell.
NOTE If lead batteries are stored for too long, especially at elevated temperatures without regular
recharging, sulfation of the active mass will occur. This can irreversibly affect battery life and performance.
– Nickel-based: The nominal voltage of nickel-cadmium (NiCd) and nickel metal hybrid
(NiMH) are fixed at 1,2V per cell.
– Lithium-ion: The nominal voltage of lithium-ion cells shall be taken from the manufacturer’s
instructions.
A.2 Discharge
A.2.1 Discharge voltage curve
The voltage of a secondary cell is fixed by the chemical reaction characteristics within the
cell. The voltage at terminals depends on the load current and the internal impedance of the
cell. This voltage can vary with the temperature, the amount the cell is charged and the age of
the cell.
Figure A.1 shows typical discharge curves for different technologies of secondary cells when
discharged at 20 % of their nominal capacity.

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Figure A.1 – Examples of cell discharge characteristics for different
technologies and for constant current discharge
NOTE The discharge curves and the initial cell voltages for lithium-ion batteries are chemistry dependent.
A.2.2 Temperature dependence
The cell discharge curve can change with temperature, refer to the manufacturer's
specifications.
A.3 Internal Impedance
A.3.1 General
The internal impedance of a secondary cell determines its current carrying capability. A low
internal resistance allows high currents. For example, the sum of the internal resistance is
equal to R + R + R .
a m i
A.3.2 Battery equivalent circuit
The battery equivalent circuit of a secondary cell is illustrated in Figure A.2.

Key
R resistance of the metallic path through the cell including the terminals, electrodes, and inter-connections
m
R resistance of the electrochemical path including the electrolyte and the separator
a
L inductance of the cell
C capacitance of the parallel plates that form the electrodes of the cell
b
R non-linear contact resistance between the plate or electrode and the electrolyte
i
Figure A.2 – Battery equivalent circuit impedance
Typical resistance of an internal cell is of the order of a few mΩ.
Where secondary cells are connected in series to increase the available voltage, internal
impedances of all cells are also connected in series, increasing the voltage drop. Rules of
association of impedances shall be used for estimating the global impedance value of the
secondary battery.
A.3.3 Voltage drop
A current circulating across an impedance results in a voltage drop at the terminals of this
impedance. During the charging time or discharging time of a secondary cell, a current is
flowing through the cell impedance as described in Figure A.2. During the charging period,
this voltage drop will result in an increased voltage applied to the batteries set by the charger.
During the discharge time, this voltage drop will decrease the available voltage at the terminal
of the batteries.
A.3.4 Thermal effects
The temperature behaviour depends on
– heat losses caused by ohmic effects;
– heat effects based by thermodynamic;
– heat capacity due to battery design.
Therefore, it is not possible to indicate general figures for thermal behaviour.
A.3.5 Time dependence
In addition, the internal resistance of most cell technologies also tends to increase towards
the end of the discharge cycle as the active chemicals are converted to their discharged state
and hence are effectively used up. This is principally responsible for the rapid drop off in cell
voltage at the end of the discharge cycle.

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As a cell ages, the resistance and therefore the cell impedance of the electrochemical system
tends to increase. This is caused for example by a reduction of the effective electrode surface
and increasing contact resistances. An increase in the internal resistance causes a drop in
the available capacity.
Comparing the actual impedance of a cell with its impedance when it was new and with the
average actual impedance of all cells within the battery can be very helpful in identifying
defective cells.
The same method used to determine the state of health of cells provides results, which are,
however, very difficult to interpret and which have a large range of uncertainties.
A.3.6 Gas evolution of lead acid, nickel-cadmium batteries and zinc dibromide
aqueous electrolyte
Where the battery is based on an aqueous electrolyte, hydrogen and oxygen gases can be
released from a battery during normal operation and also in case of excess of charging
current (overcharge).
The rate at which the gasses are released and the required ventilation system in a stationary
battery location shall be in accordance with IEC 62485-2.
WARNING – A hydrogen concentration between 4 % and 77 % is considered flammable and
can lead to an explosion in case of ignition. The ventilation system in a stationary battery
location should be designed to keep hydrogen concentration below 1 %.

Annex B
(informative)
Technical characteristics for battery load
B.1 C-rate
NOTE "C-rate" is a conventional term. More precise definitions of discharged current are given in IEC 61434.
Rated capacity is defined according to the application for lead acid batteries. For stationary
batteries the rate is 0,10 C or a 10 h discharge
A battery rated at 1 C means that a battery with a capacity of 1 Ah should provide a current
of 1 A for one hour, or should provide 0,5 A for two hours when rated at 0,5 C, or should
deliver 2 A for 30 min when rated at 2 C. See Figure B.1.
To obtain a reasonably good capacity reading, manufacturers commonly rate lead acid at
0,10 C, or a 20 h discharge.
Figure B.1 – Typical discharge curves of lead acid
as a function of C-rate as a parameter
B.2 Battery discharge performance
Battery discharge performance depends on the load the battery has to supply.
Figure B.2 shows that the effective capacity of a deep discharge lead acid battery is almost
doubled as the discharge rate is reduced from 1,0 C to 0,05 C. For discharge times less than
one hour (high C-rates) the effective capacity falls off dramatically.

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Figure B.2 – Capacity characteristic as a function of discharge time
The effectiveness of charging is similarly influenced by the rate of charge.
The following conclusion can be drawn from the graph of Figure B.2:
– Care should be exercised when comparing battery capacity specifications to ensure that
comparable discharge rates are used.
B.3 Ripple effects
The nickel-cadmium battery is tolerant to high ripple and will accept ripple currents of up to
20 % of the C capacity. In fact, the only effect of a high ripple current is that of increased
water decomposition or heat generation.
This contrasts with the VRLA battery where relatively small ripple currents can cause battery
overheating and will reduce life and performance.

Annex C
(normative)
Battery accommodation
C.1 General
Batteries shall be housed in protected accommodations. If required, electrical accommodation
or a restricted access area should be provided. During commissioning and servicing of the
battery installation, only a skilled person should perform this function.
The following kinds of accommodation can be chosen:
– separate rooms for batteries in buildings (see Clause C.2);
– specially separated areas in electrical accommodation (see Clause C.3);
– cabinets or enclosures inside or outside buildings;
– battery compartments in appliances.
The following factors shall be taken into consideration when selecting the accommodation:
a) protection from external hazards, for example fire, water, shock, vibration, vermin;
b) protection from hazards generated by the battery, for example high voltage, explosion
hazards, electrolyte hazards, corrosion and ground short effects;
c) protection from access by an ordinary person;
d) protection from extreme environmental influences for example temperature, humidity,
airborne contamination.
C.2 Specific requirements for separate battery rooms
Depending on the type and size of the batteries, the following requirements shall apply when
using a separate battery room.
a) The floor shall be designed to withstand the load of the batteries. Reserve margin shall be
taken into consideration for future extension.
b) The electrical installation shall be carried out in accordance with the standards on erection
of electrical installations in buildings.
c) If access is restricted to authorized personnel, the doors shall be lockable and of anti-
panic type. The anti-panic door shall swing outwards. The doors shall only be lockable
from the outside. From the inside, the door shall easily be opened by means of an
emergency mechanism.
d) When using vented cell type batteries, the floor shall be impermeable and chemically
resistant to the electrolyte or the battery cells shall be placed in suitable trays.
e) The ventilation can be subject to regulatory requirements, the ventilated air shall be
exhausted in
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