ISO 8714:2023

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 2023
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ii
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
iii
Foreword
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
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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— deletion of the former Annexes A, B and C (regional tests) because their information is obsolete.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.
iv
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).
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.
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.
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.
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.
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
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