ISO 23828:2008

INTERNATIONAL ISO
STANDARD 23828
First edition
2008-05-01
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 2008
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©  ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Measurement accuracy . 2
4.1 General. 2
4.2 Hydrogen measurement accuracy. 2
5 Hydrogen consumption measurement. 2
5.1 General. 2
5.2 Pressure method. 3
5.3 Gravimetric method. 3
5.4 Flow method. 3
6 Test procedure . 3
6.1 General condition . 3
6.2 Vehicle condition . 3
6.3 Chassis dynamometer conditions . 4
6.4 Fuel consumption tests. 5
6.5 Measurement over scheduled driving test.5
6.6 Correction of the test results for FCHEV. 6
7 Presentation of results. 6
Annex A (informative) Test procedure in Japan . 7
Annex B (informative) Test procedure in Europe . 13
Annex C (informative) Test procedure in the USA. 17
Annex D (normative) Pressure method. 23
Annex E (normative) Gravimetric method . 25
Annex F (normative) Flow method . 27
Annex G (informative) Current method. 28
Annex H (informative) Determination of tank surface temperature measuring points . 30
Annex I (informative) Test results of hydrogen consumption of test vehicle. 34
Annex J (normative) Allowable energy change . 36
Annex K (normative) Linear correction method using a correction coefficient for FCHEV. 37
Annex L (informative) Procedure to obtain correction coefficient for FCHEV. 38
Bibliography . 40

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 through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 23828 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 21,
Electrically propelled road vehicles.

iv © ISO 2008 – All rights reserved

Introduction
Fuel cell vehicles (FCV) include the following types:
⎯ pure fuel cell vehicle (PFCV), in which the fuel cell system is the only on-board energy source for
propulsion and auxiliary systems;
⎯ fuel cell hybrid electric vehicle (FCHEV), in which the fuel cell system is integrated with an on-board
rechargeable energy storage system (RESS) for electric energy supply to propulsion and auxiliary
systems.
FCHEV design options include:
a) externally chargeable or non-externally chargeable;
b) rechargeable energy storage system (RESS): battery or capacitor;
c) driver-selected operating modes: if the FCHEV has no driver-selected operating mode, it has only an
FCHEV mode.
Table 1 shows the classification of FCHEV.
Table 1 — Classification of FCHEV
Chargeability Operating mode
FCHEV mode
externally chargeable
EV mode
FCHEV
FCHEV mode
non-externally chargeable
EV mode
This International Standard is applicable to PFCV and to non-externally chargeable FCHEV with FCHEV
mode only (see shaded boxes in Table 1).
INTERNATIONAL STANDARD ISO 23828:2008(E)

Fuel cell road vehicles — Energy consumption measurement —
Vehicles fuelled with compressed hydrogen
1 Scope
This International Standard specifies the procedures for measuring the energy consumption of fuel cell
passenger cars and light duty trucks which use compressed hydrogen and which are not externally
chargeable.
Annexes A, B and C describe procedures specific to particular regions.
2 Normative references
The following referenced documents are indispensable for the application 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 1176, Road vehicle — Masses — Vocabulary and codes
ISO 3833, Road vehicles — Types — Terms and definitions
ISO 10521-1, Road vehicles — Road load — Part 1: Determination under reference atmospheric conditions
ISO 10521-2, Road vehicles — Road load — Part 2: Reproduction on chassis dynamometer
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3833 and ISO 1176 and the
following apply.
3.1
battery state of charge
battery SOC
residual capacity of battery available to be discharged
NOTE Battery state of charge is normally expressed as a percentage of full charge.
3.2
charge balance of battery
change of charge in battery during test period
NOTE Charge balance of battery is normally expressed in A·h.
3.3
electric vehicle operation mode
EV operation mode
mode of a FCHEV in which only the RESS is used for the vehicle propulsion and possibly auxiliary systems
3.4
fuel cell hybrid electric vehicle operation mode
FCHEV operation mode
mode of a FCHEV in which both RESS and fuel cell system are used sequentially or simultaneously for
vehicle propulsion
NOTE The fuel cell system can also charge the RESS during propulsion or standstill.
3.5
fuel cell vehicle
FCV
electric vehicle using a fuel cell power system for vehicle propulsion
NOTE A FCV can have additionally a RESS or other power sources for vehicle propulsion.
3.6
fuel cell hybrid electric vehicle
FCHEV
electric vehicle using a RESS and a fuel cell power system for vehicle propulsion
3.7
pure fuel cell vehicle
pure FCV
FCV using only a fuel cell power system for vehicle propulsion
3.8
rechargeable energy storage system
RESS
system that stores energy for delivery of electric energy and that is rechargeable
EXAMPLE Batteries, capacitors.
4 Measurement accuracy
4.1 General
Measurement accuracy shall be in accordance with national standards.
4.2 Hydrogen measurement accuracy
Test apparatus shall assure the accuracy of measurement of ± 1 % for the total mass of hydrogen
consumption during the test cycle, unless otherwise specified in the relevant annexes.
5 Hydrogen consumption measurement
5.1 General
Various methods for the measurement of hydrogen consumption have been developed which reflect the
current state of studies in the field. Hydrogen consumption shall be measured using one of the following:
⎯ pressure method;
⎯ gravimetric method;
⎯ flow method.
2 © ISO 2008 – All rights reserved

These three methods, which are described in detail in Annexes D, E and F, have been shown to give
sufficiently equivalent results. Other methods may also become applicable if they show comparable
equivalence and reliability.
5.2 Pressure method
Hydrogen consumption is determined by measuring the pressure and temperature of gas in the high-pressure
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.
5.3 Gravimetric method
Hydrogen consumption is calculated by measuring the weight of the high-pressure hydrogen tank before and
after the test. The tank used for the test shall be suitable for measuring weight.
5.4 Flow method
The amount of hydrogen supplied to and consumed by a vehicle is measured by a flow meter.
6 Test procedure
6.1 General condition
The test shall be conducted after preparation of the vehicle and test apparatus as described in this clause.
6.2 Vehicle condition
6.2.1 General
The vehicle shall be clean, and the windows and air entries that are not needed for the correct operation of the
vehicle and the drive system shall be closed by the normal operating controls.
The lighting, signalling and auxiliary devices shall be turned off, except those required for testing and for usual
day-time operation of the vehicle.
6.2.2 Vehicle stabilization
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 Annex A, B or C (as appropriate).
6.2.3 Vehicle appendages
Vehicles shall be tested with normal appendages (mirrors, bumpers, etc.). Where necessary, certain items
(e.g. hub caps) may be removed for safety on the dynamometer.
6.2.4 Vehicle test mass
The vehicle test mass shall be selected in accordance with Annex A, B, or C.
6.2.5 Tyres
6.2.5.1 General
Tyres recommended by the vehicle manufacturer shall be used.
6.2.5.2 Tyre pressure
When the vehicle tyres are at ambient temperature, they shall be inflated to the pressure specified by the
vehicle manufacturer for the chosen test (track or chassis dynamometer).
6.2.5.3 Tyre conditioning
Tyres shall be conditioned as recommended by the vehicle manufacturer. See Annex A, B, or C for additional
requirements.
6.2.6 Lubricants
The vehicle lubricants specified by the manufacturer shall be used.
6.2.7 Gear shifting
If the vehicle is fitted with a manually shifted gear box, gear shifting positions shall correspond to the test
procedures described in Annexes A, B and C. However, the shift positions may be selected and determined
previously in accordance with the vehicle characteristics.
6.2.8 Regenerative braking
If the vehicle has regenerative braking, the regenerative braking system shall be enabled for all dynamometer
testing. If a vehicle is equipped with an antilock braking system (ABS) or a traction control system (TCS) and
is tested on a single-roll dynamometer, these systems may inadvertently interpret the non-movement of the
set of wheels that are off the dynamometer as a malfunctioning system. If so, modifications to these systems
shall be made to achieve normal operation of the remaining vehicle systems, including the regenerative
braking system.
6.2.9 RESS stabilization
The RESS shall have been stabilized with the vehicle, as defined in 6.2.2, or by equivalent conditioning.
6.3 Chassis dynamometer conditions
6.3.1 General
The vehicle generally should be tested on a single-roll chassis dynamometer. A four-wheel-drive vehicle 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.
A four-wheel-drive dynamometer test may be performed when a modification for a single-roll dynamometer
test is not possible for a specific four-wheel-drive vehicle.
6.3.2 Dynamometer calibration
The dynamometer shall be calibrated as specified by the vehicle manufacturer, or in accordance with the
specifications indicated in the service manual provided by the dynamometer manufacturer.
6.3.3 Dynamometer warm-up
The dynamometer shall be warmed up sufficiently prior to the testing.
4 © ISO 2008 – All rights reserved

6.3.4 Determining the dynamometer load coefficient
The determination of vehicle road load under reference atmospheric conditions shall conform to ISO 10521-1,
and the reproduction on a chassis dynamometer shall conform to ISO 10521-2 or national standards. 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.
6.4 Fuel consumption tests
6.4.1 General
Depending on the region concerned, the appropriate procedure shall be followed from Annex A, B, or C.
Details and common procedures for each test mode are described below.
6.4.2 Vehicle preconditioning
Vehicle preconditioning shall be carried out in accordance with the annex appropriate for the region. In the
case of FCHEV, the RESS state of charge may be pre-adjusted by charging or discharging, to obtain a
suitable energy difference in RESS between the start and the end of test.
6.4.3 Vehicle soak
The vehicle shall be soaked in accordance with the appropriate regional procedure prescribed in Annex A, B,
or C.
6.5 Measurement over scheduled driving test
For the measurement of hydrogen consumption, the test vehicle shall be driven on the chassis dynamometer
in accordance with the running mode prescribed for the region (see Annex A, B, or C, as appropriate). The
hydrogen consumption can be measured by one of the methods described in Annex D, E, or F, or by an
alternative method that provides equivalent accuracy.
The hydrogen consumption is determined by means of one of the following equations:
22,414
−3
−3 w××10
b ×10
m
t0
C== (1)
F1
L L
m
−3
b××10
−3 t0
w ×10
22,414
C== (2)
F2
L L
22,414
−3
−3wQ××10×
H
bQ××10
m
t0H
C== (3)
F3
L L
where
C is the hydrogen consumption per unit distance, in m /km, referred to volume at normal conditions
F1
(273 K; 101,3 kPa);
C is the hydrogen consumption per unit distance, in kg/km, referred to weight;
F2
C is the hydrogen consumption per unit distance, in MJ/km, referred to caloric value;
F3
L is the distance, in km;
b is the hydrogen consumption at normal conditions (273 K, 101,3 kPa);
t0
w is the hydrogen consumption, in g;
m is the molecular weight of hydrogen (2,016);
Q is the lower calorific value of hydrogen (10,8 MJ/Nm ).
H
6.6 Correction of the test results for FCHEV
6.6.1 General
After the FCHEV has been tested, the hydrogen consumption shall be corrected if the energy difference in the
RESS between the start and the end of test is above the limit described in 6.6.2.
6.6.2 Allowable limit for RESS energy change for FCHEV
The allowable limit for RESS energy change is
||∆ E u0,01× E (4)
RESS CF
where
∆E is the energy change in RESS over the test cycle;
RESS
E is the energy of consumed fuel over the test cycle.
CF
Further details are described in Annex J.
6.6.3 Correction procedure using a correction coefficient
The hydrogen consumption at ∆E = 0 shall be calculated by using a correction coefficient to be provided
RESS
by the vehicle manufacturer. Details on the acquisition and the application of the correction coefficient are
given in Annex K.
NOTE Annex L gives recommendations on the data collecting procedure to obtain the correction coefficient.
7 Presentation of results
Test results should be recorded in accordance with Annex I. The fourth significant digit should be rounded off
to provide the hydrogen consumption rate to three significant digits.
Other data should be recorded as required by the regional regulations.

6 © ISO 2008 – All rights reserved

Annex A
(informative)
Test procedure in Japan
A.1 General
This annex describes the typical procedures and related conditions in Japan for measuring the fuel
consumption of passenger cars and light duty trucks, as defined in Japanese regulations.
A.2 Accuracy for determining vehicle road load and others
When determining road load, the accuracy shall conform to ISO 10521-1 and ISO 10521-2.
A.3 Driving procedure
A.3.1 General
The gear manipulation in each operational condition specified in Tables A.1 and A.2 shall be performed
smoothly and quickly in accordance with the instructions in this clause.
A.3.2 Vehicles with manual transmission
A.3.2.1 The idling operation refers to a condition in which the accelerator pedal is not depressed, with the
transmission gear in neutral.
A.3.2.2 The transmission gear shall be shifted to the low gear position (or such a gear in instances where
the “low” gear position should read otherwise in Tables A.1 and A.2) 5 s before the idling operation mode is
switched to the acceleration mode.
A.3.2.3 For deceleration, the clutch shall be disengaged at a speed of 10 km/h during the deceleration
operation from 20 km/h to 0 km/h, and at a speed of 20 km/h during the deceleration operation from 40 km/h
to 0 km/h, as specified in Tables A.1 and A.2. In the same way, the clutch shall be disengaged at a speed of
30 km/h during the deceleration operation from 70 km/h to 0 km/h, as specified in Table A.2.
A.3.2.4 On vehicles with a 6-speed transmission in which it is not possible to drive by operating the shift
lever in respective gear positions as specified in Table A.2 because of the running performance of the vehicle,
driving may be carried out in accordance with the example of the 5-speed transmission specified in Table A.2.
A.3.2.5 If the revolutions of the motor of the test vehicle exceed the revolution speed at which the motor
delivers its maximum output during the operation of the test vehicle, the gear position that is one step higher
than the original gear may be used. In this case, the vehicle speed at which the gearshift takes place shall be
the vehicle speed corresponding to the revolution speed at which the motor delivers its maximum output.
A.3.3 Vehicle with automatic transmission
The selector position shall remain in drive position. No further manipulation shall be made.
A.3.4 Vehicles with other transmissions
Gear changes shall be made taking into consideration the running characteristics of the tested vehicle with
transmissions other than those described in A.3.2 and A.3.3.
A.4 Vehicle test mass
The test vehicle mass shall be obtained when two persons (each of an assumed mass of 55 kg) or a mass of
110 kg are loaded on the test vehicle, under the “unloaded state” prescribed in the Safety Regulations for
Road Vehicles, Ministry of Transportation Ordinance No. 67, 1951, Article 1, paragraph 1, item (3).
A.5 Tyre conditioning
Tyres shall be conditioned as recommended by the vehicle manufacturer, shall have accumulated a minimum
of 100 km (62 miles) and shall have at least 50 % of the original usable tread depth remaining.
A.6 Dynamometer inertia setting
The equivalent inertia mass set for the chassis dynamometer shall be the standard value of equivalent inertia
mass specified in the right column of Table A.3, corresponding to the vehicle test mass specified in the left
column of Table A.3.
However, if the specified equivalent inertia mass is not available on the chassis dynamometer being used, the
equivalent inertia mass of within +10 % of the specified standard value may be used.
8 © ISO 2008 – All rights reserved

Table A.1 — Operation conditions, vehicle speed, acceleration/deceleration of 10 mode
Duration Acceleration
Mode Operation Vehicle Cumulative
of Standard gear positions or
no. conditions speed time
operation deceleration
(3+OD)-
3-speed 4-speed 5-speed
km/h s s speed m/s
transmission transmission transmission
transmission
1 idling — 20 20 — — — — —
a a
(0-15) Low (0-15) Low
a a
2 acceleration 0-20 7 27 (0-20) Low (0-20) Low 0,78
a a
(15-20) 2nd (15-20) 2nd
constant
3 20 15 42 2nd 2nd 2nd 2nd —
speed
4 deceleration 20-0 7 49 2nd 2nd 2nd 2nd 0,78
5 idling — 16 65 — — — — —
a a
(0-15) Low (0-15) Low
a a
(0-20) Low (0-20) Low
a a
6 acceleration 0-40 14 79 (15-30) 2nd (15-30) 2nd 0,78
a a
(20-40) 2nd (20-40) 2nd
a a
(30-40) 3rd (30-40) 3rd
constant
7 40 15 94 Top 3rd Top 4th —
speed
8 deceleration 40-20 10 104 Top 3rd Top 4th 0,59
constant
9 20 2 106 Top-2nd 3rd-2nd Top-3rd 4th-3rd —
speed
10 acceleration 20-40 12 118 2nd 2nd 3rd 3rd 0,49
40-20 10 128 Top 3rd Top 4th 0,59
11 deceleration
20-0 7 135 Top 3rd Top 4th 0,78
a
Figures in brackets represent vehicle speeds for respective gear positions.

Key
Y vehicle speed (km/h)
X time (s)
Figure A.1 — 10 Mode, vehicle speed versus time
Table A.2 — Operation conditions, vehicle speed, acceleration/deceleration of 15 mode
Duration Acceleration
Mode Operation Vehicle Cumulative
of Standard gear positions or
no. conditions speed time
operation deceleration
3-speed (3+OD)-speed 4-speed 5-speed 6-speed
km/h s s (m/s )
transmission transmission transmission transmission transmission
1 idling — 65 65 — — — — — —
a a a a a
(0-20) Low (0-20) Low (0-15) Low (0-15) Low (0-15) Low
a a a a a
2 acceleration 0-50 18 83 0,78
(20-40) 2nd (20-40) 2nd (15-35) 2nd (15-35) 2nd (15-35) 2nd
a a a a a
(40-50) Top (40-50) 3rd (35-50) 3rd (35-50) 3rd (35-50) 3rd
constant
3 50 12 95 Top 3rd Top 4th 4th —
speed
4 deceleration 50-40 4 99 Top 3rd Top 4th 4th 0,69
constant
5 40 4 103 Top 3rd 3rd 3rd 3rd —
speed
a
(40-50) 3rd
6 acceleration 40-60 16 119 Top 3rd 3rd 3rd 0,39
a
(50-60) 4th
constant
7 60 10 129 Top 3rd Top 4th 5th —
speed
8 acceleration 60-70 11 140 Top 3rd Top 4th 5th 0,29
constant
9 70 10 150 Top OD Top Top Top —
speed
10 deceleration 70-50 10 160 Top OD Top Top Top 0,59
constant
11 50 4 164 Top 3rd Top 4th 5th —
speed
12 acceleration 50-70 22 186 Top 3rd Top 4th 5th 0,29
constant
13 70 5 191 Top OD Top Top Top —
speed
70-30 20 211 Top OD Top Top Top 0,59
14 deceleration
30-0 10 221 — — — — — 0,88
15 idling — 10 231 — — — — — —
a
Figures in brackets represent vehicle speeds for respective gear positions.

Key
X time, s
Y vehicle speed, km/h
Figure A.2 — 15 Mode, vehicle speed versus time
10 © ISO 2008 – All rights reserved

Table A.3 — Standard value of equivalent inertia mass versus test vehicle mass
Test vehicle mass Standard value of equivalent inertia mass
m I
V
kg kg
m u 562 500
V
562 < m u 687 625
V
687 < m u 812 750
V
812 < m u 937 875
V
937 < m u 1 125 1 000
V
1 125 < m u 1 375 1 250
V
1 375 < m u 1 625 1 500
V
1 625 < m u 1 875 1 750
V
1 875 < m u 2 125 2 000
V
2 125 < m u 2 375 2 250
V
2 375 < m u 2 625 2 500
V
2 625 < m u 2 875 2 750
V
2 875 < m u 3 250 3 000
V
continues in increments of 500 kg continues in increments of 500 kg
A.7 Test procedure
A.7.1 Preconditioning for vehicle
The test vehicle shall be placed on the chassis dynamometer and warmed up continuously for about 20 min at
a constant speed of 60 ± 2 km/h. The vehicle shall then be further warmed up with 15 mode operation (as
shown in Table A.2) performed once.
A.7.2 Operating cycle
After the preconditioning, the operating cycle shall start with the idling operation for 24 s, then 10 mode
operation (as shown in Table A.1) shall be repeated 3 times consecutively, and 15 mode operation (as shown
in Table A.2) shall be performed once.
A.7.3 Tolerance of vehicle speed and time
The test vehicle shall be operated within a range of ±2 km/h of the specified speed, and within a range of ±1 s
of the specified time, during the operations specified in Tables A.1 and A.2. The tolerable range is shown in
the area marked in Figure A.3.
If the testing time deviates from the tolerance, but the deviation time is less than 1 s at the time of gear shift
and transition of operation mode, the test result is acceptable.
For those vehicles that cannot reach the acceleration specified in Tables A.1 and A.2 with full stroke of the
accelerator pedal, the aforesaid requirement shall not apply.
If the test vehicle cannot reach the level of acceleration specified in Tables A.1 and A.2, the acceleration
obtained from fully depressing the accelerator pedal shall be used.
Key
1 upper tolerable line
2 reference mode
3 lower tolerable line
4 reference point
Figure A.3 — Tolerance of vehicle speed and time in 10-15 driving mode
12 © ISO 2008 – All rights reserved

Annex B
(informative)
Test procedure in Europe
B.1 General
Based on the legal requirements in Europe, this annex specifies the specific preconditioning procedures and
relevant test equipment for the determination of hydrogen consumption of PFCV and FCHEV non-externally
chargeable, and with FCHEV mode only of categories M1 and N1 with a maximum permissible total mass (in
accordance with ISO 1176) of 3 500 kg.
NOTE The outline given in this annex contains only those elements essential to understanding the procedure. For
further details, reference is made to the relevant clauses and subclauses in the regulations UNECE R 101 and
1)
UNECE R 83.
B.2 Test equipment
B.2.1 Chassis dynamometer
Features, accuracy, load and inertia setting, calibration and other steps to prepare the chassis dynamometer
to be used are prescribed in UNECE R 83, Annex 4, 4.1, 5.1 and 5.2, and in Annex 4, Appendixes 2 and 3.
The adjustment of the inertia simulators to the vehicle's translatory inertias shall be in accordance with
Table B.1, given in UNECE R 83, Annex 4, 5.1.
B.2.2 Chassis dynamometer
Features, accuracy, load and inertia setting, calibration and other steps to prepare the chassis dynamometer
to be used are prescribed in UNECE R 83, Annex 4, 4.1, 5.1 and 5.2 and in Appendixes 2 and 3 of Annex 4.
The adjustment of the inertia simulators to the vehicle's translatory inertias shall be in accordance with
Table B.1 (as given in UNECE R 83, Annex 4, 5.1).

1) This annex is based on the following editions of the two regulations:
⎯ UNECE R 101: Trans/WP.29/GRPE/2004/2, 30 October 2003;
⎯ UNECE R 83: E/ECE/324 Rev.1/Add.82/Rev.2 E/ECE/Trans/505, 30 October 2001.
It does not necessarily reflect subsequent amendments to UNECE R 101 and UNECE R 83.
Table B.1 — Equivalent inertia of the dynamometer related to the reference mass of the vehicle
Reference mass of the vehicle Equivalent inertia
m I
V
kg kg
m u 480 455
V
480 < m u 540 510
V
540 < m u 595 570
V
595 < m u 650 625
V
650 < m u 710 680
V
710 < m u 765 740
V
765 < m u 850 800
V
850 < m u 965 910
V
965 < m u 1 080 1 020
V
1 080 < m u 1 190 1 130
V
1 190 < m u 1 305 1 250
V
1 305 < m u 1 420 1 360
V
1 420 < m u 1 530 1 470
V
1 530 < m u 1 640 1 590
V
1 640 < m u 1 760 1 700
V
1 760 < m u 1 870 1 810
V
1 870 < m u 1 980 1 930
V
1 980 < m u 2 100 2 040
V
2 100 < m u 2 210 2 150
V
2 210 < m u 2 380 2 270
V
2 380 < m u 2 610 2 270
V
2 610 < m 2 270
V
B.2.3 Test equipment for hydrogen measurement methods
For specific test equipment for the hydrogen measurement methods, see Clause 5 and Annexes D, E and F.
B.3 Test vehicle
B.3.1 General
The test vehicle shall be in running order, as determined by the manufacturer, with all the equipment provided
as standard.
B.3.2 Test mass
The mass of the vehicle under test (referred to as “reference mass” in UNECE R 83, 2.2) shall be the
“unloaded mass” plus a uniform figure of 100 kg. The “unloaded mass” (see UNECE R 83, 2.2.1) is the mass
of the vehicle in running order, without load and persons, but with the hydrogen tank 90 % full.
14 © ISO 2008 – All rights reserved

B.3.3 Tyres
The tests shall be performed with standard width tyres, as provided by the vehicle manufacturer. Alternatively,
the prescription of UNECE R 83, Annex 4, Appendix 3, 4.1.2, may be applied, i.e. only the widest of the
standard widths or the widest minus one (in case of more than three standard widths) shall be chosen.
The tyre pressure shall comply with the vehicle manufacturer specification, but may be increased by up to
50 % when the test is carried out on a two roller dynamometer (see UNECE R 83, Annex 4, 5.3.2).
B.4 Test cycle
The test cycle to be applied shall be the same as that prescribed for the Type I test. This test, including
allowable tolerances, is described in UNECE R 83, Annex 4, Appendix 1.
The test cycle is made up of one Part 1 (urban) cycle, consisting of four elementary urban cycles, and one
Part 2 (extra-urban) cycle, as illustrated roughly in Figure B.1 and described in Table B.2.

Key
X time, s
Y vehicle speed, km/h
1 Part 1 (urban) cycle
2 Part 2 (extra-urban) cycle
3 elementary urban cycle
Figure B.1 — Test cycle
Table B.2 — General information on the test cycle
Parameter Urban cycle Extra-urban cycle
Average speed 19 km/h 62,6 km/h
Maximum speed 50 km/h 120 km/h
Effective running time 4 × 195 s = 780 s (13 min) 400 s (6 min 40 s)
Theoretical distance 4 × 1 013 km = 4 052 km 6 955 km

B.5 Test procedure
B.5.1 Preconditioning of the vehicle
The vehicle shall be stabilized in accordance with the vehicle manufacturer’s specification, followed by two
consecutive full test cycles (see Clause B.4).
B.5.2 Conditioning of the vehicle
After preconditioning in accordance with B.5.1, the vehicle shall be kept in a room with a relative constant
temperature of between 20 °C and 30 °C for at least 6 h, until the lubricant and coolant temperatures are
within ±2 °C of the room temperature.
B.5.3 Performance of the test
B.5.3.1 General
After preconditioning and conditioning in accordance with B.5.1 and B.5.2, respectively, one complete test
cycle shall be run in accordance with Clause B.4. The test equipment shall comply with Clause B.2 and the
test vehicle shall comply with Clause B.3. The following requirements also shall be met during the test.
B.5.3.2 Additional conditions
The temperature shall be between 20 °C and 30 °C and the absolute humidity between 5,5 g and 12,2 g
H O/kg dry air.
B.5.3.3 Performing the different steps of the test cycle
The test shall be performed in accordance with the prescriptions of the vehicle manufacturer, starting with the
activation of the propulsion system and followed by applying the test cycle. To match the allowable tolerances
of the test cycle, the procedure recommended by the vehicle manufacturer should be applied.
The hydrogen consumption shall be measured using one of the methods described in Clause 5 and
Annexes D, E and F, respectively, and in the case of FCHEV it shall be corrected, if necessary.
16 © ISO 2008 – All rights reserved

Annex C
(informative)
Test procedure in the USA
C.1 Background
This annex describes the test procedure recommended for use in the USA and in other countries that use
SAE (Society of Automotive Engineers, Inc.) methods, for measuring fuel consumption and range of fuel cell
and hybrid fuel cell electric vehicles fuelled by compressed gaseous hydrogen. This annex makes reference to
SAE J2572:2006 as the specific governing document.
C.2 General
This annex prescribes the uniform chassis dynamometer test procedures for fuel cell and hybrid fuel cell
electric vehicles designed to be driven on public roads. Low speed vehicles are not covered in this annex.
Instructions are given for measuring and calculating the fuel consumption and range using two test types:
⎯ the “city” fuel consumption test using the Urban Dynamometer Driving Schedule (UDDS), and
⎯ the “highway” fuel consumption test using the Highway Fuel Economy Driving Schedule (HFEDS).
This annex covers only fuel cell vehicles fuelled with compressed gaseous hydrogen and hybrid fuel cell
electric vehicles, also fuelled with compressed gaseous hydrogen, and which have a rechargeable energy
storage system (RESS) (battery or capacitor).
C.3 General test information
C.3.1 Driving schedules
The driving schedules to be used for vehicle testing provided by the United States Environmental Protection
Agency (EPA) are the Urban Dynamometer Driving Schedule (UDDS) and the Highway Fuel Economy Driving
Schedule (HFEDS). The City Fuel Economy Test, which uses the UDDS, is detailed in SAE J2572:2006, 6.1.
The Highway Fuel Economy Test, which uses the HFEDS, is detailed in SAE J2572:2006, 6.2.
C.3.2 Battery state of charge
If the net energy of the battery/capacitor system increases or decreases by less than or equal to 1 % of the
total hydrogen energy consumed by the vehicle during the course of the test, the application of a correction
equation is not necessary, i.e. no correction calculation is necessary if
∆ stored electrical energy
u1%
total fuel energy consumed
where both the change in stored electrical energy (∆E ) and the total fuel (H ) energy consumed, reported
RESS 2
to one decimal point (e.g. 0,1 g), are expressed in units of energy (J). The lower net heating value for
hydrogen gas is used to convert the total hydrogen consumed into units of A·h, using a factor of 120 000 J/g.
Expressed in terms of the energy content of hydrogen per unit of weight, the calculation is as follows:
|∆ EM|u 0,01××120 000 (C.1)
RESS
where M is the total mass of hydrogen consumed over each phase of the test (MUDDS1, MUDDS2,
MHWFET), in g.
All mass values are reported to the nearest 0,1 g.
All distances are reported to the third decimal place (0,001 km).
All fuel consumption values are reported to the nearest 0,000 1 kg/km.
C.4 Test requirements
C.4.1 Vehicle condition
C.4.1.1 General
Prior to initiation of testing and during testing, the overall condition and configuration of the vehicle shall be as
delineated in SAE J2572:2006, 4.1 and subsequent subclauses, all of which are represented below.
C.4.1.2 Vehicle stabilization
Prior to testing, the test vehicle shall be stabilized as determined by the manufacturer to a minimum of
1 600 km (1 000 miles), but not more than 9 978 km (6 200 miles) using the durability driving schedule
specified in CFR Title 40, Part 86, Appendix IV, section (a), or an equivalent schedule. For all preparations
and testing, hydrogen complying with fuel specified by the SAE or the appropriate U.S. government agency
shall be used, and that fuel shall comply with the fuel quality guidance specified in SAE J2719.
C.4.1.3 Vehicle appendages
Vehicles shall be tested with normal appendages (mirrors, bumpers, etc.). Certain items (e.g. hub caps) may
be removed where necessary for safety on the dynamometer. If an off-board fuel source is used for the test,
the test vehicle may include a connector to receive the fuel from that source.
C.4.1.4 Accessories
All accessories shall be turned off.
C.4.1.5 Vehicle test mass
The vehicle shall be tested at loaded vehicle weight [curb weight plus 136 kg (300 lb)].
C.4.1.6 Tyres
Manufacturer's recommended tyres shall be used. For dynamometer testing, tyre pressures should be set at
the beginning of the test at the pressure used to establish the dynamometer road-load coefficients (see C.4.3)
and shall not exceed levels necessary for safe operation. Tyres shall be conditioned as recommended by the
vehicle manufacturer, have accumulated a minimum of 100 km (62 miles) and have at least 50 % of the
original usable tread depth remaining.
C.4.1.7 Lubricants
The vehicle lubricants normally specified by the manufacturer shall be used.
18 © ISO 2008 – All rights reserved

C.4.1.8 Regenerative braking
If the vehicle has regenerative braking, the regenerative braking system shall be enabled for all chassis
dynamometer testing, except for track coast down testing. If the regenerative braking level is adjustable, it
shall be set in accordance with the manufacturer’s specification prior to starting dynamometer testing.
Operation of the regenerative braking system shall not cause speed and time tolerances specified by the test
driving schedule to be exceeded.
C.4.1.9 Vehicle capability
The test vehicle shall be able to maintain the speed and distance tolerances required by the UDDS and
HFEDS schedules.
C.4.1.10 Fuel cell stack condition
The stack shall have been aged with the vehicle as detailed in C.4.1.2, or equivalent conditioning.
C.4.1.11 Propulsion battery/capacitor condition
The propulsion system battery/capacitor shall have been aged with the vehicle, as detailed in C.4.1.2, or
equivalent conditioning. The vehicle shall have an access point for measurement of current readings into and
out of the energy storage device. Reading from a vehicle onboard current measurement system may be used
provided that ±1 % NIST (National Institute of Standards and Technology) traceability can be demonstrated.
C.4.2 Environmental conditions
All test sequences shall be conducted with an ambient temperature within the range of 20 °C to 30 °C (68 °F
to 86 °F).
C.4.3 Dynamometer
Use of an electric 48-inch single roll chassis dynamometer, or equivalent, is required for fuel cell vehicle and
hybrid fuel cell electric vehicle testing. All factors concerning the dynamometer, specifically its capability
requirements, configuration, calibration, warm-up and settings, are presented in SAE J2572:2006, 4.5 and
subsequent subclauses, and these give further reference to other specific requirements as contained in
CFR Title 40, Part 86, section 135-90 (i). The determination of the dynamometer load coefficients shall be as
specified in SAE J2264.
C.4.4 Instrumentation
All instrumentation requirements for the test, including the list of instruments and instrument accuracy
requirements, are presented in SAE J2572:2006, 4.6 and subsequent subclauses. All instrumentation
calibration must be NIST traceable to within ±1,0% of the full scale of the appropriate range.
C.5 Required data collection
The data that must be collected regarding the vehicle, test conditions, instrumentation, fuel consumed and the
dynamometer type, settings and results, are detailed in SAE J2572:2006, 5.1, 5.2 and subsequent subclauses.
C.6 Testing the vehicle
C.6.1 General
The driving schedules provided by the U.S. Environmental Protection Agency (EPA) are u
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