ISO/TR 17326:2023

Fuel cell road vehicles - Cold start performances under sub-zero temperature - Vehicles fuelled with compressed hydrogen

This document describes the test methods for the cold start performances of fuel cell hybrid electric vehicles (FCHEV) under sub-zero temperature conditions. This document applies to FCHEV as passenger cars and light duty trucks with a maximum authorized total mass of 3 500 kg (hereinafter referred to as vehicle) and fuelled with compressed hydrogen.

Véhicules routiers à piles à combustible — Performances de démarrage à froid à des températures inférieures à zéro — Véhicules alimentés en hydrogène comprimé

General Information

• Status: Published
• Publication Date: 11-Dec-2023
• 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: 12-Dec-2023
• Due Date: 31-Mar-2025
• Completion Date: 12-Dec-2023

Overview

ISO/TR 17326:2023 specifies test methods for assessing cold start performances of fuel cell hybrid electric vehicles (FCHEV) fuelled with compressed hydrogen under sub‑zero temperature conditions. It applies to passenger cars and light‑duty trucks with a maximum authorized total mass of 3 500 kg. The document defines soak conditions, cold‑start and launch test procedures, data acquisition and processing, and reporting requirements to evaluate vehicle readiness, fuel‑cell power delivery and hydrogen consumption during cold starts.

Key topics and technical requirements

• Scope & terminology
  • Applies to FCHEV (fuel cell hybrid electric vehicles) up to 3 500 kg and uses terms from ISO/TR 8713.
• Test temperature control
  • Test chamber temperature controlled within ±2 °C of setpoint; preferred setpoint −7 °C, range 0 °C to −30 °C.
  • Soak period: effective soak time ≥ 12 h.
• Soak and start procedures
  • Vehicle and RESS (rechargeable energy storage system) preparation allowed per manufacturer; adjustments logged.
  • Option to use an external hydrogen tank per ISO 23828 for hydrogen‑consumption measurement.
• Cold start performance test
  • Data sampling begins at vehicle start and continues until shutdown; monitor fuel‑cell stack voltage/current and RESS voltage/current.
  • Record time to vehicle “READY” and time until fuel‑cell stack output reaches ≥ 1 kW; hydrogen consumption during the interval may be recorded.
• Launch performance test
  • Determine dynamometer load coefficient (road‑load reproduction per ISO 10521 series) and simulate sub‑zero road behavior.
  • After soak and start, operate at full accelerator until fuel‑cell power reaches ≥ 50% of rated power, record time and hydrogen used; then perform a regional ADT drive cycle.
• Instrumentation accuracy
  • Examples: Time ±0.1 s, Speed ±1 %, Temperature ±1 °C, Mass ±0.5 kg (see Table 1).
• Data processing & records
  • Specifies data acquisition requirements, processing methods (Annex B) and test records (Annex C).

Applications and users

ISO/TR 17326:2023 is intended for:

• Vehicle manufacturers validating FCHEV cold‑start performance and thermal management design
• Test laboratories and certification bodies conducting reproducible cold‑start and launch tests
• R&D teams optimizing fuel‑cell control strategies and hydrogen consumption during cold conditions
• Suppliers of fuel‑cell systems, RESS and hydrogen storage assessing component behavior in low temperatures

Practical uses include design verification, homologation support, component benchmarking, and comparative testing across vehicle models.

Related standards

• ISO/TR 8713 - Electrically propelled road vehicles - Vocabulary
• ISO 14687 - Hydrogen fuel quality
• ISO 23828 - FCHEV related testing
• ISO 10521 series - Road load and chassis dynamometer methods
• ISO 6469 series - Safety and fuel‑cell system definitions

Keywords: ISO/TR 17326:2023, fuel cell road vehicles, cold start performances, sub‑zero temperature, compressed hydrogen, FCHEV, test methods, hydrogen consumption, dynamometer.

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 17326
First edition
2023-12
Fuel cell road vehicles — Cold start
performances under sub-zero
temperature — Vehicles fuelled with
compressed hydrogen
Véhicules routiers à piles à combustible — Performances de
démarrage à froid à des températures inférieures à zéro — Véhicules
alimentés en hydrogène comprimé
Reference number
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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or ISO’s member body in the country of the requester.
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Test instrumentation .2
6 Vehicle conditions . 2
7 Test temperature conditions .3
8 Test methods . 3
8.1 General . 3
8.2 Soak method under sub-zero temperature . 3
8.3 Cold start performance test under sub-zero temperature . 3
8.4 Launch performance test under sub-zero temperature . 4
8.4.1 Determining the dynamometer load coefficient . 4
8.4.2 Setting of vehicle's driving mode . 4
8.4.3 Test method . 4
8.4.4 Tolerance of drive cycle test . 5
8.4.5 Test termination criteria . 5
8.5 Requirements of data acquisition . 5
9 Test data processing . 5
10 Test records . .5
Annex A (informative) Test process . 6
Annex B (informative) Energy consumption data processing method. 7
Annex C (informative) Test records for cold start performances of FCHEV under sub-zero
temperature . 9
Bibliography .11
iii
Foreword
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Electrically propelled vehicles.
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iv
TECHNICAL REPORT ISO/TR 17326:2023(E)
Fuel cell road vehicles — Cold start performances under
sub-zero temperature — Vehicles fuelled with compressed
hydrogen
1 Scope
This document describes the test methods for the cold start performances of fuel cell hybrid electric
vehicles (FCHEV) under sub-zero temperature conditions.
This document applies to FCHEV as passenger cars and light duty trucks with a maximum authorized
total mass of 3 500 kg (hereinafter referred to as vehicle) 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, 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
ADT
applicable driving test
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).
[SOURCE: ISO 23274-2:2021, 3.1]
3.2
FCHEV
fuel cell hybrid electric vehicle
electrically propelled vehicle with a rechargeable energy storage system (RESS) (3.6) and a fuel cell
system as power sources for vehicle propulsion
[SOURCE: ISO 23828:2022, 3.7]
3.3
fuel cell stack
assembly of two or more fuel cells, which are electrically connected
[SOURCE: ISO 6469-3:2021, 3.20]
3.4
fuel cell system
system typically containing the following subsystems: fuel cell stack (3.3), air processing system, fuel
processing system, thermal management, water management, and their control system
[SOURCE: ISO 6469-3:2021, 3.21]
3.5
rated power of the fuel cell system
maximum continuous power output from the fuel cell system (3.4) as specified by the vehicle
manufacturer
3.6
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 6469-1:2019, 3.22]
3.7
RESS SOC
RESS state of charge
residual capacity of rechargeable energy storage system (RESS) (3.6) available to be discharged
1)
[SOURCE: ISO/TR 11954:— , 3.11]
4 Abbreviated terms
ECU electronic control unit
VIN vehicle identification number
5 Test instrumentation
The test instrumentation has the accuracy levels as given in Table 1, unless otherwise specified in the
relevant regional ADT standard.
a
Table 1 — Accuracy of measured values
Item Unit Accuracy
Time s ±0,1 s
Distance m ±0,1 %
Speed km/h ±1 %
Mass kg ±0,5 %
Temperature °C ±1 °C
a
If necessary, DC current and voltage accuracy are specified by the vehicle manufacturer.
6 Vehicle conditions
The vehicle conditions are the following:
— the outline structure and technical parameters of the vehicle is maintained by default;
1) Second edition under preparation. Stage at the time of publication: ISO/DTR 11954:2023.
— the viscosity of the lubricating oil for mechanical moving parts is based on the vehicle manufacturer's
requirements;
— the corresponding coolant is selected for a variety of ambient temperatures according to the vehicle
manufacturer's requirements;
— ISO 14687 and the equivalent regional standard apply to the test fuel.
7 Test temperature conditions
From the beginning of the soak to the end of the test, the test temperature (i.e. test chamber
temperature) is controlled within +2 °C of the set temperature.
The test temperature is set in agreement with the vehicle manufacturer. It is preferable -7 °C, but not
higher than 0 °C and not lower than -30 °C.
The test temperature is measured at the test chamber's cooling fan outlet at a minimum frequency of
0,1 Hz.
For the soak area, the sensor is at least 10 cm away from the wall of the soak area and shielded from
direct air flow.
8 Test methods
8.1 General
The whole test process is given in Figure A.1.
8.2 Soak method under sub-zero temperature
The vehicle is soaked according to the following steps.
a) Before the start of the soak, it is possible to adju
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