ISO 8714:2023

Electric road vehicles — Reference energy consumption and range — Test procedures for passenger cars and light commercial vehicles

This document specifies test procedures for measuring the reference energy consumption and reference range of purely electrically propelled passenger cars and commercial vehicles of a maximum authorized total mass (in accordance with ISO 1176) of 3 500 kg and a maximum speed of 70 km/h or more.

Véhicules routiers électriques — Consommation d'énergie de référence et autonomie de référence — Modes opératoires d'essai pour voitures particulières et véhicules utilitaires légers

General Information

• Status: Published
• Publication Date: 25-Jul-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: 26-Jul-2023
• Due Date: 01-Jul-2023
• Completion Date: 26-Jul-2023

Relations

• Revises: ISO 8714:2002 - Electric road vehicles — Reference energy consumption and range — Test procedures for passenger cars and light commercial vehicles
• Effective Date: 06-Jun-2022

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 8714
Second edition
2023-07
Electric road vehicles — Reference
energy consumption and range — Test
procedures for passenger cars and
light commercial vehicles
Véhicules routiers électriques — Consommation d'énergie de
référence et autonomie de référence — Modes opératoires d'essai
pour voitures particulières et véhicules utilitaires légers
Reference number
ISO 8714:2023(E)
© ISO 2023

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ISO 8714:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© 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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Website: www.iso.org
Published in Switzerland
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ISO 8714:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Test sequence . 2
5.1 General . 2
5.2 Selection of ADT cycle . 2
5.3 Deviations in speed trace for vehicles with less maximum speed than the
maximum speed of the selected ADT cycle . 2
5.4 Selection of the number of ADT cycles for the shortened test . 3
5.5 Speed determination and procedure for running a CSS . 3
6 Tolerances . 3
7 End-of-test criteria . 4
8 Measurement of range and energy consumption . 5
8.1 General . 5
8.2 Parameters, units and accuracy of measurements . 5
8.3 Test conditions . 6
8.3.1 Vehicle conditions . 6
8.3.2 Ambient temperature conditions . 6
8.4 Test procedure . 6
8.4.1 General . 6
8.4.2 Charging of the RESS . 7
8.4.3 Application of the designated test sequence and calculation for results . 8
8.4.4 Test procedure overviews . 11
9 Presentation of results .11
Annex A (informative) Test results of reference energy consumption and range of test
vehicle . .12
Annex B (normative) Determination of CSS speed .14
Bibliography .18
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ISO 8714:2023(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
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 8714:2002), which has been technically
revised.
The main changes are as follows:
— addition of shortened test;
— deletion of the former Annexes A, B and C (regional tests) because their information is obsolete.
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 8714:2023(E)
Electric road vehicles — Reference energy consumption
and range — Test procedures for passenger cars and light
commercial vehicles
1 Scope
This document specifies test procedures for measuring the reference energy consumption and
reference range of purely electrically propelled passenger cars and commercial vehicles of a maximum
authorized total mass (in accordance with ISO 1176) of 3 500 kg and a maximum speed of 70 km/h or
more.
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 8715, Electric road vehicles — Road operating characteristics
ISO 10521 (all parts), Road vehicles — Road load
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
complete electric vehicle kerb mass
mass of the electric vehicle including the rechargeable energy storage system (RESS), without
occupants or load, but with combustion heater fuel, cooling liquid, window-washer fluid, lubricating oil,
tools and spare wheel, and on-board charger and portable charger or part of it, if provided as standard
equipment by the vehicle manufacturer
Note 1 to entry: Adapted from ISO 8715.
3.2
reference energy consumption
quantity of electrical energy from the external AC electric power source needed to recharge the
rechargeable energy storage system (RESS), divided by the distance covered or calculated, after the
vehicle has been driven through a specified test sequence
Note 1 to entry: The reference energy consumption is usually expressed in watt-hours per kilometre (Wh/km).
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ISO 8714:2023(E)
3.3
reference range
distance covered by or calculated for an electric vehicle over a designated test sequence on a fully
charged rechargeable energy storage system (RESS), to the end of the test sequence as defined by the
end-of-test criteria
Note 1 to entry: The reference range is usually expressed in kilometres (km).
3.4
test mass
sum of the complete electric vehicle kerb mass (3.1) plus the maximum authorized pay mass (including
driver) if it is equal or less than 180 kg; 180 kg, if the maximum authorized pay mass exceeds 180 kg
but is less than or equal to 360 kg; half of the maximum authorized pay mass if this pay mass exceeds
360 kg
4 Abbreviated terms
ADT applicable driving test
CCT consecutive cycle test
CSS constant speed segment
RESS rechargeable energy storage system
5 Test sequence
5.1 General
There are two test methods for measuring the reference energy consumption and reference range
of purely electrically propelled vehicles on a chassis dynamometer, the consecutive cycle test (CCT)
(see 8.4.3.2) and the shortened test (see 8.4.3.3). The CCT repeats the selected applicable driving test
(ADT) cycle (see 5.2) as a test sequence until the end-of-test criterion is reached (see Clause 7). The test
sequence of the shortened test consists of a selected number of ADT cycles (see 5.2 and 5.4) followed
by a constant speed segment (CSS) (see 5.5). The CSS is performed for discharging the RESS by a higher
electrical load than the average ADT cycle load in order to shorten the overall test duration.
The RESS discharging in the shortened test shall be performed by running the vehicle in a CSS or
optionally with a constant power discharge via the DC fast charging port (see 5.5).
5.2 Selection of ADT cycle
Select a relevant regional ADT cycle for the definition of the test sequence. The selected ADT cycle
applies to either CCT in 8.4.3.2 or shortened test in 8.4.3.3.
The same test sequence shall be used to define energy consumption and range. Every effort shall be
made to conduct the tests by following the reference curve within the tolerances given in Clause 6, see
Figure 1.
5.3 Deviations in speed trace for vehicles with less maximum speed than the maximum
speed of the selected ADT cycle
Vehicles with a maximum speed capability that is less than the maximum speed of the selected ADT
cycle shall be operated at fully activated accelerator control when the speed trace cannot be followed.
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ISO 8714:2023(E)
Speed trace violations according to Clause 6 under this circumstances shall not void a test, if the vehicle
speed is higher than 70 km/h. Deviations from the driving cycle shall be recorded.
NOTE If the relevant regional ADT standard, where the selected regional ADT cycle belongs to, includes
requirements for a reduced test procedure for vehicles which cannot follow the target speed curve, these
requirements for a reduced speed curve are taken into account.
5.4 Selection of the number of ADT cycles for the shortened test
In the shortened test, the selected ADT cycle shall be continued consecutively until an additional cycle
after the total range at the cycle end exceeds 40 km to warm-up the relevant drive train components. In
the additional ADT cycle test, the energy consumption and range shall be measured under the assumed
conditions of a fully warmed-up drive train. The total number of these ADTs, N, is defined as the number
of ADTs for the shortened test prior to the CSS.
5.5 Speed determination and procedure for running a CSS
As the second part of the shortened test, a CSS is performed following the required number of ADT
cycles as described in 5.4. A CSS is also performed in order to discharge the RESS for preconditioning
before the normal charging, see 8.4.2.
A relevant CSS running speed value for the selected ADT cycle shall be determined by choosing one of
the two methods described in Annex B, see Clauses B.2 and B.3. If a shortened test method with a CSS
for the selected ADT cycle is available in the relevant regional ADT standard, then this CSS speed value
can be used.
Optionally, the RESS discharging can be performed with a constant power discharge via the DC fast
charging port. The determination of the value for power for the RESS discharging and some information
necessary for the test are described in Annex B, see Clause B.4.
A CSS shall be run targeting the CSS speed as follows:
The vehicle on the chassis dynamometer shall be accelerated steadily to the specified CSS speed within
60 s. If the CSS speed cannot be reached within 60 s, the accelerator control shall be fully activated until
the CSS speed is reached. When the vehicle reached the CSS speed, the speed shall be maintained until
the end-of-test criteria according to Clause 7 are satisfied.
6 Tolerances
Tolerances on speed and time in the test sequence shall be as shown in Figure 1.
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ISO 8714:2023(E)
Key
X time [s]
Y speed [km/h]
1 reference speed curve
2 tolerance of speed, in km/h
3 tolerance of time, in seconds [s]
Figure 1 — Reference curve and tolerances
A tolerance on speed of within ± 2,0 km/h and a tolerance on time of within ± 1,0 s shall be geometrically
combined at each point as in Figure 1. One deviation of up to 4 s beyond these tolerances is permitted
in any drive cycle. This exception shall not be allowed to delay the determination of the end of the test
sequence. The total time-out of tolerances shall be mentioned in the test report.
7 End-of-test criteria
The end-of-test criteria are defined as follows.
a) For vehicles capable of following the speed trace of the selected ADT cycle, the test termination
criterion is defined as when the vehicle–due to power limitations–is incapable of maintaining the
speed tolerances as defined in Clause 6.
b) For vehicles with a maximum speed capability that is less than the maximum speed of the selected
ADT cycle, it shall be operated at fully activated accelerator control when the speed trace cannot be
followed.
If the speed trace is equal or lower than 70 km/h, the test termination criterion is defined as when
the vehicle is incapable of maintaining the speed tolerances as defined in Clause 6. If the speed
trace is higher than 70 km/h, the test termination criterion is defined as when the vehicle, while
operated at fully activated accelerator control is unable to reproduce the best-effort speed versus
time relationship established by the vehicle in the first selected ADT cycle. The applicable drive
tolerances for the best-effort trace are as defined in Clause 6.
c) For all vehicles the test termination criterion is defined as when the vehicle is given an indication
from the on-board instrumentation to the driver to stop the vehicle, e.g. for safety reasons.
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ISO 8714:2023(E)
When one of the test termination criteria has occurred, the driver shall immediately apply the brake and
the vehicle shall stop within 60 s. At the stop of the vehicle, the test is completed and all measurement
activities shall be terminated.
At the shortened test, the DC measurement device additionally shall count the energy values at the test
termination point.
NOTE DC measurement is necessary for E correction.
AC
8 Measurement of range and energy consumption
8.1 General
The following test method specifies the measurement of the AC electric energy, DC electric energy and
the distance, and then the calculation of reference range and reference energy consumption.
8.2 Parameters, units and accuracy of measurements
Table 1 specifies parameters and their units and accuracy of measurements.
Table 1 — Parameters, units and accuracy of measurements
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 the full scale. (Pulsed power electronics measurement needs a wide
dynamic range even if it has a small power.)
For the DC energy measurement, wideband meter (power analyser) or wideband ampere-hour meter
for pulsed power electronics 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 10 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
all current leaving and entering the RESS.
The data of the RESS control unit shall be alternatively applied if the accuracy of the data certifies
corresponding accuracy in Table 1.
NOTE If the test vehicle's RESS controller data are not sufficiently accurate, the accuracy of the controller's
data are displayed on the data sheet. The accuracy of the resulting specific energy consumption and range can be
estimated and are also on the data sheet.
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ISO 8714:2023(E)
8.3 Test conditions
8.3.1 Vehicle conditions
The test mass shall follow the requirements given in ISO 8715. If the requirement for the test mass is
given in the relevant regional ADT standard, then it can be used.
The determination of vehicle road load and the reproduction on the chassis dynamometer shall be in
accordance with the ISO 10521 series. The same setting on the chassis dynamometer shall be used
throughout the test regardless of CCT or shortened test.
The relevant regional ADT standard can be used if it specifies how to determine the vehicle road load.
The vehicle tyres shall be inflated to the pressure specified by the vehicle manufacturer according to
the specifications of the chassis dynamometer when the tyres are at ambient temperature.
The viscosity of oils used for the lubrication of mechanical moving parts shall conform to the
specifications of the vehicle manufacturer.
The lighting and light signalling and auxiliary devices shall be 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.) shall be in the operating range specified by the vehicle manufacturer.
For the RESS conditioning, the test driver shall follow the procedure recommended by the vehicle
manufacturer for keeping the temperature of the RESS in the normal operating range.
The vehicle shall be driven at least 300 km before the test with the RESS that is installed in the test
vehicle.
8.3.2 Ambient temperature conditions
Test steps shall be carried out at room temperature between (25 ± 5) °C.
8.4 Test procedure
8.4.1 General
The test procedure consists of the following steps:
a) charging of the RESS (discharging or charging, preconditioning and normal charging) in accordance
with 8.4.2. For shortened test, the energy from the external AC electric power source for charging
the RESS (E ) can be measured (see 8.4.2.3);
AC_mes_pre-test
b) applying the appropriate test sequence (see 5.2), and measuring the range and the DC energy
consumption from the RESS, if applicable, and the AC energy from the external AC electric power
source for charging the RESS (see 8.4.3);
c) for CCT, measuring travelled range, the AC energy from the external AC electric power source for
charging the RESS after the test and calculation of the reference energy consumption (see 8.4.3.3);
d) for the shortened test, measuring travelled range, AC energy from the external AC electric power
source for charging the RESS after the test, DC energy from the RESS, and calculation of the
reference energy consumption and reference range (see 8.4.3.3.2.3).
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ISO 8714:2023(E)
8.4.2 Charging of the RESS
8.4.2.1 General
Unless otherwise prescribed by the vehicle manufacturer or the RESS manufacturer, the initial charge
of the RESS shall be performed as follows.
8.4.2.2 Discharging the RESS
8.4.2.2.1 Setting the remaining RESS level for discharge driving (preconditioning) before full
charge
Prior to discharge driving (preconditioning), the remaining state of charge (SOC) of the RESS should
be adjusted so that the vehicle can run a distance of up to 50 km at CSS speed. After adjusting the SOC,
soak for 9 h or more at the test temperature condition. The soak time can be reduced by agreement
between the test institute and customer.
For discharging, a constant power discharge of the RESS via the DC fast charging port can replace
running a CSS on a chassis dynamometer (see Annex B, B.4).
If the SOC level is lower than the requested minimum level, the RESS shall first be charged at least to the
requested minimum SOC level before discharging in 8.4.2.2.3.
8.4.2.2.2 Vehicle movement
If it is necessary to move the vehicle, push or tow the vehicle so that it does not regenerate or discharge.
Exposure to temperatures other than the test environment temperature shall be limited to 30 min.
8.4.2.2.3 Preconditioning (discharge running) for full charge of RESS
Discharging the RESS shall be carried out by driving the vehicle at a constant speed defined by CSS on
the chassis dynamometer.
Stop the discharge, if the end-of-test criteria according to Clause 7 are satisfied.
8.4.2.2.4 Application of a normal charge
Soak and charge the vehicle at ambient temperature for 11 h according to 8.4.2.3 (normal charging
procedure), then start the test within a 1 h period. If charging takes less than 11 h, soaking shall be
continued for 11 h. If charging takes more than 11 h, start the test within a 1 h period after charging is
completed.
When charging and soaking are completed, push or tow the vehicle onto the chassis dynamometer.
8.4.2.3 Normal charging procedure
8.4.2.3.1 General
The AC energy measurement equipment shall be placed between the external AC electric power source
and the vehicle inlet.
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.
The AC energy shall be measured after the test termination.
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ISO 8714:2023(E)
For the shortened test, the AC energy can be measured optionally after preconditioning if the discharge
conditions at the test and for the preconditioning are the same. The measured AC energy values can be
used instead of the post-test measurements, see 8.4.3.3.1.
8.4.2.3.2 End-of-charge criteria
The end-of-charge criteria shall correspond to a charging time of 11 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.
8.4.2.3.3 Fully charged RESS
A RESS is fully charged when charged according to the normal charging procedure (see 8.4.2.3.1) and
the end-of-charge criteria (see 8.4.2.3.2).
8.4.3 Application of the designated test sequence and calculation for results
8.4.3.1 General
If the test sequence is performed by CCT only, the total range and the AC energy from the external AC
energy source for charging the RESS shall be measured after the test.
If the vehicle can run more than N times of the selected ADT cycle (see 5.4), the shortened test according
to 8.4.3.3 can be the alternative test procedure instead of the CCT.
If the test sequence is performed by the shortened test, measured DC energy (E ) from the RESS
DC_cycle_n
th
and travelled range (d ) in each n ADT cycle and in the CSS shall be measured.
cycle_n
NOTE n represents the ADT cycle counter, starting with number 1 up to number N, where the last ADT cycle
prior to the CSS is performed.
The total DC energy from the end of initial charge to the end of test (E ) and to the point where the
DC
vehicle stops after end of test (E ) and the AC energy from the external AC energy source for
DC_mes
charging the RESS shall be measured.
Unless otherwise requested by the ADT standard to which the selected ADT cycle belongs to, up to
three interruptions of no longer than 15 min in total are permitted between the test sequences, out of
respect for human needs. In the CSS of the shortened test, interruptions of up to 10 min per 1 h driving
are permitted. During all optional interruption periods, the key or power switch shall be in the “off”
position, the hood shall be closed, the test cell fan shall be off, and the brake pedal not depressed.
In the case of the shortened test, interruption during the ADT cycle delays the completion of vehicle
warm-up and may cause errors in each calculation result. Therefore, interruptions should be made only
during CCS or, if interrupted during an ADT cycle, the interruption time should be minimized.
8.4.3.2 Consecutive cycle test
8.4.3.2.1 Test procedure
The specified test sequence shall start within 1 h after soak and end-of-charge (8.4.2.3.2).
The test sequence shall continue until the end-of-test criterion is reached (see Clause 7).
In any case, the total range, d , travelled up to the end of test and to the final stop of the vehicle shall
ADT
be measured.
The RESS charging according to
...