ISO/TR 11954:2024

Fuel cell road vehicles - Performance measurement - Vehicles fuelled with compressed hydrogen

This document specifies test methods for the measurement of performance, such as acceleration, maximum speed and hill climbing ability, of fuel cell hybrid electric vehicles (FCHEV) as passenger cars and light duty trucks with a maximum authorized total mass of 3 500 kg and fuelled with compressed hydrogen.

Véhicules routiers avec pile à combustible — Mesure des performances — Véhicules alimentés par hydrogène comprimé

General Information

• Status: Published
• Publication Date: 04-Jan-2024
• ICS: 43.120 - Electric road vehicles
• Technical Committee: ISO/TC 22/SC 37 - Electrically propelled vehicles
• Drafting Committee: ISO/TC 22/SC 37 - Electrically propelled vehicles
• Current Stage: 6060 - International Standard published
• Start Date: 05-Jan-2024
• Due Date: 25-Feb-2025
• Completion Date: 05-Jan-2024

Relations

• Revises: ISO/TR 11954:2008 - Fuel cell road vehicles - Maximum speed measurement
• Effective Date: 06-Jun-2022

Overview

ISO/TR 11954:2024 - “Fuel cell road vehicles - Performance measurement - Vehicles fuelled with compressed hydrogen” - is a Technical Report from ISO that specifies standardized test methods to measure driving performance of fuel cell hybrid electric vehicles (FCHEV) (passenger cars and light‑duty trucks up to 3 500 kg) using compressed hydrogen. The second edition updates scope, adds driving performance tests and definitions, and revises preconditioning and RESS (rechargeable energy storage system) state‑of‑charge procedures.

Key topics and technical requirements

• Scope and vehicle type: Applies to FCHEV passenger cars and light‑duty trucks with maximum authorised total mass ≤ 3 500 kg, fuelled with compressed hydrogen.
• Performance tests specified:
  • Maximum speed and maximum thirty‑minutes speed (v30)
  • Acceleration ability (e.g., 0 → 50 km/h, 50 → 80 km/h)
  • Speed uphill (highest average speed on a given slope over 1 km)
  • Hill starting ability (maximum slope to start over 10 m)
• Preconditioning and test sequencing:
  • Hydrogen refuelling procedures and fuel quality per ISO 14687 (or regional equivalent)
  • RESS state‑of‑charge (SOC) adjustment and preconditioning for externally chargeable FCHEV
  • Vehicle warm‑up, driving mode selection and minimum pre‑use driving distance (≥ 300 km with onboard fuel cell)
• Test conditions and constraints:
  • Ambient temperature ranges: outdoor 5 °C–32 °C, indoor 20 °C–30 °C; atmospheric pressure 91–104 kPa
  • Air density limited to ≤ 7.5% deviation from reference (formula provided)
  • Track and tyre conditions, vehicle loading to specified test mass and standard accessory settings
• Measurement parameters and accuracies (examples):
  • Time ±0.1 s; distance ±0.1 %; speed ±1 % or ±0.1 km/h; mass ±0.5 %; tyre pressure ±1.5 %
  • DC current measurement considerations for pulsed power electronics and RESS energy measurement

Applications and users

ISO/TR 11954:2024 is practical for:

• Vehicle manufacturers developing and validating FCHEV performance and drivability
• Test laboratories and certification bodies conducting standardized performance trials
• Regulators and type‑approval authorities assessing compliance and safety claims
• R&D teams, fleet operators and energy infrastructure planners evaluating hydrogen vehicle capabilities

The standard provides repeatable, comparable test methods to benchmark acceleration, hill climb, sustained speed and hill‑start performance for compressed‑hydrogen FCHEV.

Related standards

• ISO/TR 8713:2019 - Electrically propelled road vehicles - Vocabulary
• ISO 14687 - Hydrogen fuel quality (referenced for fuel specification)
• ISO 23828:2022 - Definitions related to FCHEV

Keywords: ISO/TR 11954:2024, fuel cell hybrid electric vehicle, FCHEV, compressed hydrogen, performance measurement, acceleration, maximum speed, hill climbing, RESS SOC, hydrogen fuel quality.

Standards Content (Sample)

Technical
Report
ISO/TR 11954
Second edition
Fuel cell road vehicles —
2024-01
Performance measurement —
Vehicles fuelled with compressed
hydrogen
Véhicules routiers avec pile à combustible — Mesure des
performances — Véhicules alimentés par hydrogène comprimé
Reference number
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Parameters, units and accuracy of measurements . 3
5 Test conditions . 3
5.1 Vehicle conditions .3
5.2 Atmospheric conditions.4
5.2.1 Ambient temperature and atmospheric pressure .4
5.2.2 Air density .4
5.2.3 Wind speed .4
5.2.4 Relative humidity .4
5.3 Track conditions .4
5.3.1 General conditions .4
5.3.2 Straight track .4
5.3.3 Loop track .5
5.3.4 Single direction test .5
6 Preconditioning of the vehicle . 5
6.1 Hydrogen refuelling .5
6.2 RESS state of charge preconditioning of externally chargeable FCHEV .5
6.3 Warming up .6
6.4 Selection of driving mode .6
7 Test sequence . 6
7.1 Test sequence for non-externally chargeable FCHEV .6
7.2 Test sequence for externally chargeable FCHEV .6
8 Test procedure . 7
8.1 Maximum speed .7
8.1.1 Standard test procedure .7
8.1.2 Single direction test procedure .7
8.2 Maximum thirty minutes speed .8
8.3 Acceleration ability (v to v ) .8
1 2
8.3.1 Acceleration ability 0 km/h to 50 km/h.8
8.3.2 Acceleration ability 50 km/h to 80 km/h .9
8.4 Speed uphill .9
8.5 Hill starting ability .9
8.5.1 Principle .9
8.5.2 Procedure .9
8.5.3 Evaluation of α .10
Annex A (informative) Test results of performance measurements .11
Annex B (informative) Quantity of electricity measurement of the RESS .13
Bibliography .15

iii
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.
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and 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 second edition cancels and replaces the first edition (ISO/TR 11954:2008), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— revision of the scope;
— addition of normative references;
— addition of terms and definitions, e.g. complete vehicle kerb mass, maximum thirty minutes speed,
acceleration, speed uphill and hill starting performance;
— addition of driving performance tests, e.g. maximum thirty minutes speed, acceleration, speed uphill
and hill starting performance;
— revision of the method for adjusting the RESS SOC;
— addition of driving mode setting method.
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.

iv
Technical Report ISO/TR 11954:2024(en)
Fuel cell road vehicles — Performance measurement —
Vehicles fuelled with compressed hydrogen
1 Scope
This document specifies test methods for the measurement of performance, such as acceleration, maximum
speed and hill climbing ability, of fuel cell hybrid electric vehicles (FCHEV) as passenger cars and light duty
trucks with a maximum authorized total mass of 3 500 kg and fuelled with 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/TR 8713:2019, Electrically propelled road vehicles — Vocabulary
3 Terms and definitions
For the purposes of this document, the following 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
acceleration ability
shortest time required to accelerate the vehicle from speed v to speed v
1 2
[SOURCE: ISO 8715:2001, 3.7, modified — Note 1 to entry was removed.]
3.2
complete vehicle kerb mass
mass of the vehicle including batteries, without occupants but with fuel, cooling liquid, window washer
fluid, lubricating oil, tools and spare wheel, on-board charger, portable charger or part of it, if provided as
standard equipment by the vehicle manufacturer
[SOURCE: ISO 8715:2001, 3.1]
3.3
dynamic loaded radius
effective radius of a tyre when it is deformed by the mass of the vehicle loaded to its test mass (3.14)
[SOURCE: ISO 8715:2001, 3.4]
3.4
FCHEV operation mode
fuel cell hybrid electric vehicle operation mode
mode of a fuel cell hybrid electric vehicle (FCHEV) (3.5) in which both a rechargeable energy storage system
(RESS) (3.10) and fuel cell system are used sequentially or simultaneously for vehicle propulsion

3.5
FCHEV
fuel cell hybrid electric vehicle
electrically propelled vehicle with a rechargeable energy storage system (RESS) (3.10) and a fuel cell system
as power sources for vehicle propulsion
[SOURCE: ISO 23828:2022, 3.7]
3.6
hill starting ability
maximum slope on which the vehicle can start moving over a minimum distance of 10 m
[SOURCE: ISO 8715:2001, 3.9]
3.7
maximum design total mass
maximum vehicle mass as specified by the vehicle manufacturer
[SOURCE: ISO 8715:2001, 3.2]
3.8
maximum speed
highest average speed which the vehicle can maintain throughout a specified test
[SOURCE: ISO/TR 8713:2019, 3.89]
3.9
maximum thirty minutes speed
v
highest average speed which the vehicle can maintain over 30 min
[SOURCE: ISO 8715:2001, 3.6, modified — Note 1 to entry was removed.]
3.10
RESS
rechargeable energy storage system
rechargeable system that stores energy for delivery of electric energy for the electric drive
EXAMPLE Battery, capacitor, flywheel.
[SOURCE: ISO/TR 8713:2019, 3.117]
3.11
RESS SOC
RESS state of charge
residual capacity of a rechargeable energy storage system (RESS) (3.10) available to be discharged
3.12
RESS operation mode
rechargeable energy storage system operation mode
mode of an fuel cell hybrid electric vehicle (FCHEV) (3.5) using only a rechargeable energy storage system
(RESS) (3.10) for vehicle propulsion
3.13
speed uphill
highest average speed which the vehicle can maintain on a given slope over a distance of 1 km
[SOURCE: ISO 8715:2001, 3.8]
3.14
test mass
sum of the complete vehicle kerb mass (3.2) plus

— the maximum authorized load mass (including driver) if it is equal or less than 180 kg;
— 180 kg, if the maximum authorized load mass exceeds 180 kg but is less than or equal to 360 kg;
— half of the maximum authorized load mass if this load mass exceeds 360 kg
[SOURCE: ISO 8715:2001, 3.3]
4 Parameters, units and accuracy of measurements
Table 1 shows parameters and their units and accuracy.
Table 1 — Parameters, units and accuracy of measurements
Parameter Unit Accuracy
Time s ±0,1 s
Distance m ±0,1 %
Air temperature °C ±1 °C
Air pressure kPa ±1 kPa
Speed km/h ±1 % or ±0,1 km/h
whichever is greater
Mass kg ±0,5 %
Tyre pressure kPa ±1,5 %
a
DC current A ±0,3 %
a
For the DC current measurement, a wideband current meter or wideband ampere-hour
meter for operation in connection with pulsed power electronics is used. Any errors in the DC
electric energy measurement system are less than 1 % of the reading or 0,3 % of full scale.
5 Test conditions
5.1 Vehicle conditions
The vehicle is loaded to the test mass according to the specification given for each test.
The vehicle tyres are inflated to the pressure specified by the vehicle manufacturer when the tyres are at
ambient temperature.
The viscosity of oils for the mechanical moving parts conforms to the specification of the vehicle
manufacturer.
The lighting, signalling and auxiliary devices are off, except those required for testing and usual day-time
operation of the vehicle.
All energy storage systems available for other than traction purposes (electric, hydraulic, pneumatic, etc.)
are charged up to their maximum level specified by the vehicle manufacturer.
The vehicle is clean, and the windows and air entries, not needed for the correct operation of the vehicle and
the drive system, are closed by the normal operating controls.
If batteries are to be operated at temperatures above ambient temperature, the driver follows the procedure
recommended by the vehicle manufacturer to keep the battery temperature within its operating range.
The vehicle is driven over at least 300 km before the test(s) with the onboard fuel cell system.
The RESS is in the state of charge required for the test to be performed.
The hydrogen fuel tank is filled according to the test to be performed with a fuel quality according to
ISO 14687 and the equivalent regional standard.

5.2 Atmospheric conditions
5.2.1 Ambient temperature and atmospheric pressure
The outdoor test is performed at an ambient temperature between 5 °C and 32 °C. Indoor tests are performed
at a room temperature between 20 °C and 30 °C. The atmospheric pressure is between 91 kPa and 104 kPa.
The tests are performed in the absence of rain and fog.
5.2.2 Air density
According to Formula (1), the air density in the test does not change more than 7,5 % compared with the air
density in the reference conditions.
Air density calculation is obtained according to Formula (1):
H T
T 0
dd=× × (1)
r 0
H T
0 T
where
d is the air density in reference conditions [d = 1,189 kg/m ];
0 0
H is the pressure during the test;
T
H is the pressure at reference conditions [H = 100 kPa];
0 0
T is the absolute temperature during the test, in kelvins;
T
T is the temperature at reference conditions [T = 293 K (20 °C)].
0 0
5.2.3 Wind speed
The average wind speed measured at a height of 1 m above the ground is less than 3 m/s. Gusts are less than
5 m/s.
5.2.4 Relative humidity
The relative humidity is less than 95 % and the track is dry.
5.3 Track conditions
5.3.1 General conditions
The measurements are taken on a dry track, which can be either a straight track or a loop track. The surface
of the track is hard, smooth, clean and give good adhesion.
5.3.2 Straight track
T
...