ISO 23274-2:2021

Hybrid-electric road vehicles - Exhaust emissions and fuel consumption measurements - Part 2: Externally chargeable vehicles

This document specifies a chassis dynamometer test procedure to determine the end of the charge-depleting state (CD) and consumed electric energy during CD state. The identification of the end of the CD state is an important step for procedures to determine exhaust emissions and fuel consumption. Final determination of exhaust emissions and fuel consumption is not included in this document. This document applies to vehicles with the following characteristics. - The vehicles are hybrid-electric road vehicles (HEV) with an internal combustion engine (ICE) and an on-board rechargeable energy storage system (RESS) for vehicle propulsion which is supplied with electric energy from an external electric power source. - A CD state, in which the electric energy in the RESS from an external electric power source is consumed, is followed by a charge-sustaining (CS) state in which the fuel energy is consumed sustaining the electric energy of the RESS. - Only batteries are assumed as the RESS of a vehicle. - The RESS is not charged while driving unless by regenerative braking and/or by generative operation driven via the ICE. - External charge for the purpose of conditioning of the RESS is not included. NOTE 1 Trolleybuses and solar powered vehicles are not included in the scope. - The vehicle is classified as a passenger car or light duty truck, as defined in the relevant regional applicable driving test (ADT) standard. - For the ICE, only liquid fuels (for example, gasoline and diesel fuel) are used. NOTE 2 In the case of vehicles with ICE using other fuel [for example, compressed natural gas (CNG), hydrogen (H2)], this document can apply except the measurement of consumed fuel; otherwise the measurement method for those using the corresponding fuel can apply. - The nominal energy of the RESS is at least 2 % of the total energy of consumed fuel over an ADT

Véhicules routiers électriques hybrides — Mesurages des émissions à l'échappement et de la consommation de carburant — Partie 2: Véhicules rechargeables par des moyens externes

General Information

• Status: Published
• Publication Date: 07-Sep-2021
• ICS: 43.120 - Electric road vehicles
• Technical Committee: ISO/TC 22/SC 37 - Electrically propelled vehicles
• Drafting Committee: ISO/TC 22/SC 37/WG 2 - Performance and energy consumption
• Current Stage: 6060 - International Standard published
• Start Date: 08-Sep-2021
• Due Date: 02-May-2022
• Completion Date: 08-Sep-2021

Relations

• Revises: ISO 23274-2:2012 - Hybrid-electric road vehicles - Exhaust emissions and fuel consumption measurements - Part 2: Externally chargeable vehicles
• Effective Date: 23-Apr-2020

Overview

ISO 23274-2:2021 specifies a chassis dynamometer test procedure for externally chargeable hybrid-electric road vehicles to determine the end of the charge‑depleting (CD) state and the electric energy consumed during CD. The standard focuses on measurement methodology for battery‑equipped HEVs (internally combustion engine + rechargeable energy storage system (RESS)) that can be recharged from an external power source. It does not provide the final determination of exhaust emissions and fuel consumption - rather, it defines the critical step of identifying when a vehicle transitions from CD to charge‑sustaining (CS) operation so that downstream emissions/fuel procedures can apply.

Key topics and technical requirements

• Scope and vehicle types: Applies to passenger cars and light‑duty trucks with batteries as RESS, RESS nominal energy ≥ 2% of total fuel energy consumed over an applicable driving test (ADT). Excludes trolleybuses and solar‑powered vehicles.
• Test environment & charging: Normal charging at (25 ± 5) °C per manufacturer procedure; typical end‑of‑charge criterion corresponds to 12 hours unless the vehicle indicates otherwise. External charge for preconditioning is excluded.
• Chassis dynamometer procedure: Defines sequence - preconditioning, soak, full initial charge, move to test room (no regenerative charging while moving), run ADTs (e.g., WLTC or UDDS), measure RESS energy balance, repeat ADTs until CD end is identified, then fully recharge and measure external AC energy delivered.
• Energy & instrumentation accuracy: Measurement equipment accuracy requirements (examples from Table 1): time ±0.1 s, speed ±1 %, temperature ±1 °C, mass ±0.5 %, current ±0.3 %, electric energy ±0.5 %.
• Determination of end of CD: Clause 6.3 (and informative Annex A) defines procedures (multiple cases) to identify the transition from CD to CS; ADTs run in CS are used only to establish that transition, not for full CS emissions/fuel results.
• Charging measurement: Electric energy delivered from the external source must be measured with metering placed between the external source and vehicle inlet; charging must start within 2 hours after test completion.

Applications and users

• Vehicle manufacturers and component suppliers for validation of hybrid control strategies and battery sizing.
• Emissions and fuel consumption test laboratories performing homologation or type‑approval prep work.
• Regulatory agencies and certification bodies needing repeatable methods to identify CD/CS boundaries.
• R&D teams analyzing real-world electric energy use in plug‑in hybrids and comparing ADT results (WLTC/UDDS).

Related standards

• ISO 23274-1 - Part 1: Non‑externally chargeable vehicles (CS test procedures)
• ISO/TR 8713 - Electrically propelled road vehicles - Vocabulary

Keywords: ISO 23274-2:2021, hybrid-electric road vehicles, charge-depleting, charge-sustaining, chassis dynamometer, RESS, state of charge, electric energy measurement, ADT, WLTC, UDDS.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 23274-2
Second edition
2021-09
Hybrid-electric road vehicles —
Exhaust emissions and fuel
consumption measurements —
Part 2:
Externally chargeable vehicles
Véhicules routiers électriques hybrides — Mesurages des émissions à
l'échappement et de la consommation de carburant —
Partie 2: Véhicules rechargeables par des moyens externes
Reference number
©
ISO 2021
© ISO 2021
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 © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols and abbreviated terms . 3
5 Test conditions and instrumentation . 3
5.1 Test conditions . 3
5.2 Test instrumentation . 3
5.3 Charging of the RESS . 4
5.3.1 Application of a normal charge . 4
5.3.2 Charging the RESS and measuring energy . 4
6 Test procedure . 4
6.1 General . 4
6.2 Test sequence . 5
6.2.1 General. 5
6.2.2 Vehicle preconditioning . 5
6.2.3 Vehicle soak . 5
6.2.4 Vehicle movement to the test room . 5
6.2.5 Measurement in each ADT . 5
6.2.6 Electric energy measurement . 5
6.3 Determination of the end of the CD state and the beginning of the CS state . 6
6.3.1 General. 6
6.3.2 Determination of the end of the CD state (case 1) . 6
6.3.3 Determination of the end of the CD state (case 2) . 7
7 Additional data evaluation of results . 9
Annex A (informative) Procedure for determining the beginning of the CS state .10
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 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.
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 23274-2:2012), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— deletion of former 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.
A list of all parts in the ISO 23274 series can be found on the ISO website.
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 © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 23274-2:2021(E)
Hybrid-electric road vehicles — Exhaust emissions and
fuel consumption measurements —
Part 2:
Externally chargeable vehicles
1 Scope
This document specifies a chassis dynamometer test procedure to determine the end of the charge-
depleting state (CD) and consumed electric energy during CD state.
The identification of the end of the CD state is an important step for procedures to determine exhaust
emissions and fuel consumption. Final determination of exhaust emissions and fuel consumption is not
included in this document.
This document applies to vehicles with the following characteristics.
— The vehicles are hybrid-electric road vehicles (HEV) with an internal combustion engine (ICE) and
an on-board rechargeable energy storage system (RESS) for vehicle propulsion which is supplied
with electric energy from an external electric power source.
— A CD state, in which the electric energy in the RESS from an external electric power source is
consumed, is followed by a charge-sustaining (CS) state in which the fuel energy is consumed
sustaining the electric energy of the RESS.
— Only batteries are assumed as the RESS of a vehicle.
— The RESS is not charged while driving unless by regenerative braking and/or by generative operation
driven via the ICE.
— External charge for the purpose of conditioning of the RESS is not included.
NOTE 1 Trolleybuses and solar powered vehicles are not included in the scope.
— The vehicle is classified as a passenger car or light duty truck, as defined in the relevant regional
applicable driving test (ADT) standard.
— For the ICE, only liquid fuels (for example, gasoline and diesel fuel) are used.
NOTE 2 In the case of vehicles with ICE using other fuel [for example, compressed natural gas (CNG),
hydrogen (H )], this document can apply except the measurement of consumed fuel; otherwise the
measurement method for those using the corresponding fuel can apply.
— The nominal energy of the RESS is at least 2 % of the total energy of consumed fuel over an ADT
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
ISO 23274-1, Hybrid-electric road vehicles — Exhaust emissions and fuel consumption measurements —
Part 1: Non-externally chargeable vehicles
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 terminological 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 schedule for a relevant region is the Worldwide Light-duty Test Cycle
(WLTC) or the Urban Dynamometer Driving Schedule (UDDS), for example.
3.2
CD state
charge-depleting state
operating mode of a hybrid-electric vehicle (3.5) with ICE in which the vehicle runs by consuming the
stored electric energy in the rechargeable energy storage system (RESS) (3.7) from an external electric
power source or along with the fuel energy simultaneously or sequentially until charge-sustaining state
(3.3)
3.3
CS state
charge-sustaining state
operating mode where the hybrid-electric vehicle (3.5) runs by consuming the fuel energy while
sustaining the electric energy of the rechargeable energy storage system (RESS) (3.7)
3.4
energy balance of RESS
ΔE
RESS
change of RESS (3.7) 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 the RESS in ampere hours (Ah) with the nominal voltage of the RESS in volts (V).
3.5
HEV
hybrid-electric vehicle
vehicle with both a rechargeable energy storage system (RESS) (3.7) and a fuelled power source for
propulsion
EXAMPLE Internal combustion engine or fuel cell systems are typical types of fuelled power sources.
3.6
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 and
discharge cut-off voltage
2 © ISO 2021 – All rights reserved

3.7
RESS
rechargeable energy storage system
rechargeable system that stores energy for the delivery of electric energy for the electric drive
EXAMPLE Batteries or capacitors.
3.8
regenerative braking
braking with conversion of kinetic energy into electric energy for charging the rechargeable energy
storage system (RESS) (3.7)
3.9
SOC
state of charge
available capacity of a rechargeable energy storage system (RESS) (3.7) or RESS subsystem expressed as
a percentage of rated capacity (3.6)
4 Symbols and abbreviated terms
CD charge-depleting
CNG compressed natural gas
CS charge-sustaining
E energy
E energy of consumed fuel
CF
H hydrogen
ICE internal combustion engine
UDDS Urban Dynamometer Driving Schedule
WLTC Worldwide Light-duty Test Cycle
5 Test conditions and instrumentation
5.1 Test conditions
The test conditions in ISO 23274-1 shall apply.
5.2 Test instrumentation
The test instrumentation shall have the accuracy levels given in Table 1, unless otherwise specified by
the relevant regional ADT standard.
Table 1 — Accuracy of measured values
Item Unit Accuracy
Time s ± 0,1 s
Distance m ± 0,1 %
Temperature °C ± 1 °C
a
Accuracy for measured value: ± 0,3 % full scale deflection or ± 1 % of reading,
whichever is greater.
Table 1 (continued)
Item Unit Accuracy
Speed km/h ± 1 %
Mass kg ± 0,5 %
a
Current A ± 0,3 %
Electric energy Wh ± 0,5 %
a
Accuracy for measured value: ± 0,3 % full scale deflection or ± 1 % of reading,
whichever is greater.
5.3 Charging of the RESS
5.3.1 Appli
...