ISO 23828:2022
(Main)Fuel cell road vehicles — Energy consumption measurement — Vehicles fuelled with compressed hydrogen
Fuel cell road vehicles — Energy consumption measurement — Vehicles fuelled with compressed hydrogen
This document specifies the procedures for measuring the energy consumption and driving range of fuel cell passenger cars and light-duty trucks that use compressed hydrogen.
Véhicules routiers avec pile à combustible — Mesurage de la consommation d'énergie — Véhicules alimentés par hydrogène comprimé
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 23828
Third edition
2022-06
Fuel cell road vehicles — Energy
consumption measurement —
Vehicles fuelled with compressed
hydrogen
Véhicules routiers avec pile à combustible — Mesurage de la
consommation d'énergie — Véhicules alimentés par hydrogène
comprimé
Reference number
ISO 23828:2022(E)
© ISO 2022
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ISO 23828:2022(E)
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© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
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ISO 23828:2022(E)
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms.3
5 Hydrogen measurement accuracy .4
6 Hydrogen consumption measurement . 4
6.1 General . 4
6.2 Pressure method. 4
6.3 Gravimetric method . . 4
6.4 Flow method . 5
7 Fuel consumption test . 5
7.1 Test conditions . 5
7.1.1 General . 5
7.1.2 Ambient temperature. 5
7.1.3 Vehicle conditions . 5
7.1.4 Chassis dynamometer conditions . 6
7.2 Test instrumentation . 6
7.3 Charging of the RESS of externally chargeable FCHEV . 7
7.3.1 Application of a normal charge. 7
7.3.2 Charging the RESS and measuring energy. 8
7.4 Hydrogen consumption tests . 8
7.4.1 General . 8
7.4.2 Vehicle preconditioning . 8
7.4.3 Vehicle soak . 8
7.4.4 Vehicle movement to the test room . 8
7.5 Measurement and calculation over applicable driving test (ADT) . 8
7.5.1 CD state . 8
7.5.2 CS state . 8
7.6 Correction of the test results for FCHEV . 9
7.6.1 General . 9
7.6.2 Allowable range of RESS energy balance . 9
7.6.3 Correction procedure by correction coefficient . 9
8 Calculation of driving range .10
8.1 Non-externally chargeable FCHEV . 10
8.2 Externally chargeable FCHEV . 10
9 Calculation of contribution of electricity and hydrogen for the driving range .10
10 Presentation of results .11
Annex A (normative) Pressure method .12
Annex B (normative) Gravimetric method.14
Annex C (normative) Flow method .16
Annex D (informative) Current method .18
Annex E (informative) Determination of tank surface temperature measuring points .20
Annex F (informative) Test results of hydrogen and electric energy consumption and
driving range of test vehicle .24
Annex G (normative) Calculation of allowable range of RESS energy change .26
Annex H (normative) Linear correction method using a correction coefficient .27
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ISO 23828:2022(E)
Annex I (normative) Usable amount of hydrogen of FCV and FCHEV .29
Annex J (normative) Test conditions and instrumentation for CD state .31
Annex K (informative) Calculation of electricity and hydrogen contribution .32
Annex L (informative) Fuel consumption measurement by vehicle refuelling .35
Bibliography .37
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ISO 23828:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
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expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 37,
Electrically propelled vehicles.
This third edition cancels and replaces the second edition (ISO 23828:2013), which has been technically
revised.
The main changes are as follows:
— deletion of Annexes A, B and C (regional tests) because their information is obsolete;
— harmonization of terms and definitions with ISO/TR 8713 and ISO 23274-1;
— addition of a method to correct the hydrogen amount in the external hydrogen supplying line;
— integration of externally chargeable FCHEV;
— calculation of driving range;
— calculation of contribution of RESS and hydrogen fuel for the driving range.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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INTERNATIONAL STANDARD ISO 23828:2022(E)
Fuel cell road vehicles — Energy consumption
measurement — Vehicles fuelled with compressed
hydrogen
1 Scope
This document specifies the procedures for measuring the energy consumption and driving range of
fuel cell passenger cars and light-duty trucks that use compressed hydrogen.
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.
ISO 10521 (all parts), Road vehicles — Road load
ISO 14687, Hydrogen fuel quality — Product specification
ISO/TR 8713, Electrically propelled road vehicles — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TR 8713 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
applicable driving test
ADT
single driving test schedule which is specified for a relevant region
Note 1 to entry: Chassis dynamometer test schedules for a relevant region are the Worldwide Light-duty Test
Cycle (WLTC) or the Urban Dynamometer Driving Schedule (UDDS), for example.
3.2
charge balance of RESS
change of charge in the rechargeable energy storage system (RESS) (3.13) during an applicable driving
test (ADT) (3.1)
Note 1 to entry: Normally expressed in ampere hours (Ah).
3.3
charge-depleting state
CD state
operating mode of an HEV in which the vehicle runs by consuming the stored electric energy in the
rechargeable energy storage system (RESS) (3.13) from an external electric power source or along with
the fuel energy simultaneously or sequentially until CS state (3.4)
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ISO 23828:2022(E)
3.4
charge-sustaining state
CS state
operating mode where the HEV runs by consuming the fuel energy while sustaining the electric energy
of the rechargeable energy storage system (RESS) (3.13)
3.5
energy balance of RESS
ΔE
RESS
change of rechargeable energy storage system (RESS) (3.13) energy state during an applicable driving
test (ADT) (3.1)
Note 1 to entry: Normally expressed in watt hours (Wh).
Note 2 to entry: For practical use, the energy balance of the RESS is approximated by multiplying the charge
balance of RESS (3.2) in ampere hours (Ah) with the nominal voltage of the RESS in volts (V).
3.6
externally chargeable FCHEV
externally chargeable fuel cell hybrid electric vehicle
fuel cell hybrid electric vehicle (FCHEV) (3.7) with a rechargeable energy storage system (RESS) (3.13)
that is intended to be charged from an external electric energy source
Note 1 to entry: External charge for conditioning of the RESS is not included.
3.7
fuel cell hybrid electric vehicle
FCHEV
electrically propelled vehicle with a rechargeable energy storage system (RESS) (3.13) and a fuel cell
system as power sources for vehicle propulsion
3.8
fuel cell vehicle
FCV
electrically propelled vehicle with a fuel cell system as the power source for vehicle propulsion
Note 1 to entry: An FCV may also have a rechargeable energy storage system (RESS) (3.13) or another power
source for vehicle propulsion.
3.9
state of charge of hydrogen
density (or mass) ratio of hydrogen in the original hydrogen tank between the original hydrogen tank
condition and the capacity at nominal working pressure (NWP) (3.11) when the system is equilibrated at
15 °C
Note 1 to entry: State of charge of hydrogen is expressed as a percentage and is computed based on the gas
density according to formula below.
Note 2 to entry: The accuracy of the NIST formula has been quantified to be to within 0,01 % from 255 K to
1 000 K with pressures to 120 MPa at the time of publication of this document.
Note 3 to entry: (%) can be calculated as follows:
ρ
1
×100
ρ
2
where
ρ is the density of hydrogen under the specific gas conditions;
1
ρ is the density of hydrogen at the nominal working pressure at a gas temperature of 15 °C.
2
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ISO 23828:2022(E)
The hydrogen densities at the two major nominal working pressures are:
— density of H at 35 MPa and 15 °C = 24,0 g/l,
2
— density of H at 70 MPa and 15 °C = 40,2 g/l.
2
Note 4 to entry: The ρ function for hydrogen is available from the National Institute of Standards and Technology
1
(NIST) at https:// nvlpubs .nist .gov/ nistpubs/ jres/ 113/ 6/ V113 .N06 .A05 .pdf.
[SOURCE: ISO 19880-1:2020, 3.78, modified — The term was originally "state of charge" and
"compressed hydrogen storage system (CHSS)" has been replaced by "original hydrogen tank".]
3.10
non-externally chargeable FCHEV
non-externally chargeable fuel cell hybrid electric vehicle
fuel cell hybrid electric vehicle (FCHEV) (3.7) with a rechargeable energy storage system (RESS) (3.13)
that is not intended to be charged from an external electric energy source
3.11
nominal working pressure
NWP
container pressure, as specified by the container manufacturer, at a uniform gas temperature of 15 °C
and full gas content
3.12
rated capacity
supplier's specification of the total number of ampere hours that can be withdrawn from a fully charged
battery pack or system for a specified set of test conditions such as discharge rate, temperature,
discharge cut-off voltage, etc.
3.13
rechargeable energy storage system
RESS
rechargeable system that stores energy for delivery of electric energy for the electric drive
EXAMPLE Batteries or capacitors.
3.14
regenerative braking
braking with conversion of kinetic energy into electric energy for charging the rechargeable energy
storage system (RESS) (3.13)
3.15
state of charge
SOC
available capacity of a rechargeable energy storage system (RESS) (3.13)or RESS subsystem expressed as
a percentage of rated capacity (3.12)
4 Symbols and abbreviated terms
ADT applicable driving test
CD charge-depleting
CS charge-sustaining
E energy
E energy of consumed hydrogen
CH2
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ISO 23828:2022(E)
ECU electronic control unit
E energy of RESS
RESS
FCHEV fuel cell hybrid electric vehicle
FCV fuel cell vehicle
HEV hybrid-electric vehicle
IEC International Electrotechnical Commission
ISO International Organization for Standardization
NWP nominal working pressure
RESS rechargeable energy storage system
SOC state of charge
UDDS Urban Dynamometer Driving Schedule
WLTC Worldwide Light-duty Test Cycle
5 Hydrogen measurement accuracy
The hydrogen measurement device shall ensure an accuracy of ±1 % for the total mass of hydrogen
consumption during the ADT, unless otherwise specified in the relevant regional ADT standard.
6 Hydrogen consumption measurement
6.1 General
Hydrogen consumption shall be measured using one of the following methods:
— pressure method (see Annex A);
— gravimetric method (see Annex B);
— flow method (see Annex C).
NOTE The current method (see Annex D) can be used.
6.2 Pressure method
Hydrogen consumption is determined by measuring the pressure and temperature of gas in the
hydrogen tank before and after the test. A tank with known internal volume that allows measurement
of gas pressure and temperature shall be used for the test. Pressure method shall be performed in
accordance with Annex A.
6.3 Gravimetric method
Hydrogen consumption is calculated by measuring the mass of the hydrogen tank before and after the
test. The gravimetric method shall be performed in accordance with Annex B.
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ISO 23828:2022(E)
6.4 Flow method
The amount of hydrogen supplied to a vehicle is measured by a flowmeter. The flow method shall be
performed in accordance with Annex C.
7 Fuel consumption test
7.1 Test conditions
7.1.1 General
For test conditions, the following applies unless otherwise specified in the relevant regional ADT
standard.
7.1.2 Ambient temperature
Tests shall be conducted at an ambient temperature of (25 ± 5) °C.
7.1.3 Vehicle conditions
7.1.3.1 Vehicle conditioning
Prior to testing, the test vehicle shall be stabilized; this includes vehicle mileage accumulation in
accordance with a manufacturer-determined distance, unless otherwise specified in the relevant
regional ADT standard.
7.1.3.2 Vehicle appendages
Vehicles shall be tested with normal appendages (mirrors, bumpers, etc.). When the vehicle is on the
dynamometer, certain items (e.g. hub caps) should be removed for reasons of safety, where necessary.
7.1.3.3 Vehicle test mass
The vehicle test mass shall be selected according to the relevant regional ADT standard.
7.1.3.4 Tyres
7.1.3.4.1 General
The correctly rated tyres as specified by the vehicle manufacturer shall be used.
7.1.3.4.2 Tyre pressure
The vehicle tyres shall be inflated to the pressure specified by the vehicle manufacturer according to
the test chosen (track or chassis dynamometer).
7.1.3.4.3 Tyre conditioning
The tyres shall be conditioned as recommended by the vehicle manufacturer.
7.1.3.5 Lubricants
The lubricants specified by the vehicle manufacturer shall be used.
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ISO 23828:2022(E)
7.1.3.6 Gear shifting
If the vehicle is fitted with a manually shifted gear box, the gear shifting positions should be selected
and determined in accordance with the vehicle manufacturer's specification.
NOTE The shift positions can be referred to the relevant regional ADT procedure.
7.1.3.7 Regenerative braking
If the vehicle has regenerative braking, the regenerative braking system shall be enabled for all
dynamometer testing except where specified in 7.1.4.4 chassis dynamometer conditions.
If the vehicle is tested on a single axle dynamometer and is equipped with systems such as an antilock
braking system (ABS) or a traction control system (TCS), those systems can inadvertently interpret
the non-movement of the set of wheels that are off the dynamometer as a malfunctioning system. If so,
these systems shall be temporally disabled for adjustment to achieve normal operation of the remaining
vehicle systems, including the regenerative braking system.
7.1.3.8 RESS conditioning
The RESS shall be conditioned with the vehicle as specified in 7.1.3.1 or by equivalent conditioning.
7.1.3.9 Test fuel
ISO 14687 or the equivalent regional standard shall apply to the test fuel.
7.1.4 Chassis dynamometer conditions
7.1.4.1 General
The vehicle should generally be tested on a single-axle chassis dynamometer. A vehicle with four-wheel
drive shall be tested by modifying the drive train of the vehicle. When the vehicle is modified, the
details shall be explained in the test report.
Double-axle chassis dynamometer testing should be performed if a modification for single-axle chassis
dynamometer testing is not possible for a specific four-wheel drive vehicle.
7.1.4.2 Dynamometer calibration
The dynamometer shall be calibrated in accordance with the specifications indicated in the service
manual provided by the dynamometer manufacturers.
7.1.4.3 Dynamometer warm-up
The dynamometer shall be warmed up sufficiently prior to testing.
7.1.4.4 Determining the dynamometer load coefficient
The determination of vehicle road load and the reproduction on a chassis dynamometer shall conform
to the ISO 10521 series. Vehicles equipped with regenerative braking systems that are activated at
least in part when the brake pedal is not depressed shall have regenerative braking disabled during the
deceleration portion of coast-down testing on both the test track and dynamometer.
7.2 Test instrumentation
The test instrumentation shall have the accuracy levels as given in Table 1, unless otherwise specified
in the relevant regional ADT standard.
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ISO 23828:2022(E)
Table 1 — Accuracy of measured values
Item Unit Accuracy
Time s ±0,1 s
Distance m ±0,1 %
Temperature °C ±1 °C
Speed km/h ±1 %
Mass kg ±0,5 %
AC electric energy Wh ±0,5 %
a
DC electric energy Wh ±0,3 %
a
DC current A ±0,3 %
a
DC voltage V ±0,3 %
a
Any errors in the DC electric energy measurement system shall be less than
1 % of the reading or 0,3 % of full scale. (Pulsed power electronics measurement
needs wide dynamic range even if small power.)
For the DC current measurement without direct voltage sensing, wideband ampere-hour meter or
wideband meter is required.
The wideband meter (power analyser) is an instrument for processing power and energy in pulsed
power electronics by current and voltage inputs. Its bandwidth shall be at least ten times as high as the
switching frequency of the pulsed power electronics, and update period of its outputs shall be 0,05 s or
less to get enough time resolution.
Voltage probes and current sensors shall be installed in such a way as to measure voltage at RESS and
FC terminals, and all current leaving and entering the RESS and leaving the FC.
The electronic control unit (ECU) shall be alternatively applied, if the accuracy of ECU data certifies
corresponding accuracy in Table 1.
NOTE If the ECU of the test vehicle has not enough accuracy, the accuracy of the data through the ECU
appears on the data sheet. The accuracy of resultant specific energy consumption and range can be estimated
and they are also on the data sheet.
7.3 Charging of the RESS of externally chargeable FCHEV
7.3.1 Application of a normal charge
7.3.1.1 Normal charging procedure
The charging of the RESS shall be carried out at an ambient temperature of (25 ± 5) °C. The normal
charging procedure shall be in accordance with the vehicle manufacturer’s specification for normal
operation.
For the normal charging procedure all types of special charging shall be excluded, for example, RESS
service charging.
7.3.1.2 End-of-charge criteria
The end-of-charge criteria shall correspond to a charging time of 12 h except if a clear indication is given
to the driver by the standard instrumentation that the RESS is not yet fully charged. In this case, the
maximum charging time shall be in accordance with the manufacturer’s specification. After charging,
the vehicle shall not be conductively connected to an external electric power source unless otherwise
specified by the manufacturer.
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ISO 23828:2022(E)
7.3.1.3 Fully charged RESS
A RESS is fully charged when charged according to the normal charging procedure (see 7.3.1.1) and the
end-of-charge criteria (see 7.3.1.2).
7.3.2 Charging the RESS and measuring energy
The vehicle shall be physically reconnected to an external electric power source within 2 h following
completion of the appropriate test sequence unless otherwise specified for relevant region.
The RESS shall then be fully charged in accordance with the normal charging procedure (see 7.3.1.1).
The electric energy, E, in Wh, delivered from an external electric power source, as well as the charging
time duration, shall be measured. The energy-measuring equipment shall be placed between the
external electric power source and the vehicle power inlet.
7.4 Hydrogen consumption tests
7.4.1 General
Depending on the region concerned, the appropriate procedure shall be followed from the relevant
regional ADT standard. Details and common procedures for each test mode are described below.
7.4.2 Vehicle preconditioning
There can be regional ADT standards that state the procedure for vehicle preconditioning, if necessary.
In the case of non-externally chargeable FCHEV, the RESS SOC may be pre-adjusted by charging or
discharging, to obtain a suitable energy difference in RESS between the beginning and the end of test.
7.4.3 Vehicle soak
The vehicle shall be soaked in accordance with the relevant regional ADT standard.
In the case of externally chargeable FCHEV, the RESS is fully charged. The normal charging procedure
shall be in accordance with the vehicle manufacturer’s specification for normal operation. The soak
should be continued until both, relevant regional ADT
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