ISO 23308-1:2020

INTERNATIONAL ISO
STANDARD 23308-1
First edition
2020-05
Energy efficiency of industrial
trucks — Test methods —
Part 1:
General
Efficacité énergétique des chariots de manutention — Méthodes
d'essai —
Partie 1: Généralités
Reference number
ISO 23308-1:2020(E)
©
ISO 2020

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ISO 23308-1:2020(E)

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© ISO 2020
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Published in Switzerland
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ISO 23308-1:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 Test conditions . 3
4.1 General . 3
4.2 Test equipment . 3
4.2.1 Test area . 3
4.2.2 Test track . 3
4.2.3 Test load and / or towing capacity . 3
4.3 Truck conditions . 3
4.4 Environmental conditions . 4
4.5 Truck maintenance . 4
4.6 Battery condition . 4
5 Measurement procedure . 5
5.1 General . 5
5.2 Operating sequence . 5
5.3 Electric trucks . 5
5.3.1 General. 5
5.3.2 Truck measurement . 5
5.3.3 Battery efficiency . 6
5.3.4 Charger efficiency . 7
5.4 Internal combustion (IC)-trucks . 7
5.5 Hybrid trucks . 7
5.6 Measurement accuracy . 7
5.7 Calculation . 8
6 Documentation . 8
6.1 Test report . 8
6.2 Declaration . 9
6.2.1 Truck energy consumption . 9
6.2.2 Battery efficiency . 9
6.2.3 Charger efficiency . 9
Annex A (normative) Determination of battery efficiency by using the synthetic discharge cycle .10
Annex B (normative) Simplified procedure to calculate the battery and charging efficiency
for lead-acid batteries .15
Annex C (informative) Calculation of the carbon dioxide equivalent.17
Bibliography .20
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ISO 23308-1:2020(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 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 110, Industrial trucks, Subcommittee
SC 5, Sustainability.
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.
This document is intended to be used in conjunction with ISO 23308-2 and/or ISO 23308-3.
A list of all parts in the ISO 23308 series can be found on the ISO website.
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ISO 23308-1:2020(E)

Introduction
The ISO 23308 series deals with the energy efficiency of industrial trucks including batteries and
battery chargers.
This document contains the procedures to determine the efficiency of trucks, traction batteries and
battery chargers. The other parts provide a specific test cycle for different truck types.
NOTE The test cycles are based on the VDI 2198 guideline. This guideline is widely accepted by industry
and is used to measure the energy consumption of electric industrial trucks and internal combustion (IC)
industrial trucks. The guideline has been in place since 1996 and it is used broadly. This approach provides for
the evaluation of the energy efficiency of trucks by comparison.
The content of this document is of relevance for the following stakeholder groups:
— machine manufacturers (small, medium and large enterprises);
— market surveillance authorities;
— machine users (small, medium and large enterprises);
— service providers, e.g. for consulting activities.
The stakeholder groups above have been given the opportunity to take part in the drafting process of
this document. The machines concerned are indicated in the scope of this document.
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INTERNATIONAL STANDARD ISO 23308-1:2020(E)
Energy efficiency of industrial trucks — Test methods —
Part 1:
General
1 Scope
This document specifies general test criteria and requirements to measure the energy consumption for
self-propelled industrial trucks (hereinafter referred to as trucks) during operation. For electric trucks,
the efficiency of the battery and the battery charger is included.
The truck specific requirements in ISO 23308-2 and ISO 23308-3 take precedence over the respective
requirements of ISO 23308-1.
This document is applicable to the in-use phase of the product life cycle.
It applies to the following truck types according to ISO 5053-1:
— counterbalance lift truck;
— articulated counterbalance lift truck;
— reach truck (with retractable mast or fork arm carriage);
— straddle truck;
— pallet-stacking truck;
— pallet truck;
— platform and stillage truck;
— pallet truck end controlled;
— order-picking truck;
— centre-controlled order-picking truck;
— towing, pushing tractor and burden carrier;
— towing and stacking tractor;
— side-loading truck (one side only);
— variable-reach container handler;
— counterbalance container handler;
— lateral-stacking truck (both sides);
— lateral-stacking truck (three sides);
— multi-directional lift truck.
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ISO 23308-1:2020(E)

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 3691-1:2011, Industrial trucks — Safety requirements and verification — Part 1: Self-propelled
industrial trucks, other than driverless trucks, variable-reach trucks and burden-carrier trucks
ISO 3691-2:2016, Industrial trucks — Safety requirements and verification — Part 2: Self-propelled
variable-reach trucks
ISO 5053-1, Industrial trucks — Terminology and classification — Part 1: Types of industrial trucks
ISO 15500-1, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 1: General
requirements and definitions
ISO 23308 (all parts), Energy efficiency of Industrial trucks — Test methods
IEC 60254-1, Lead acid traction batteries — Part 1: General requirements and methods of tests
IEC 62620:2014, Secondary cells and batteries containing alkaline or other non-acid electrolytes —
Secondary lithium cells and batteries for use in industrial applications
EN 589, Automotive fuels — LPG — Requirements and test methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5053-1 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 http:// www .electropedia .org/
3.1
battery
electrical power source consisting of battery cells, connectors of cells, battery controller (if applicable,
e.g. controller for Li-Ion batteries) and battery enclosure that is ready to use in a truck
3.2
battery state of charge
measured capacity (in Ampere hours [Ah]) of the battery divided by the maximum rated capacity [Ah],
expressed as a percentage
3.3
carbon dioxide equivalent
CDE
quantity that describes, for a given mixture and amount of greenhouse gas, the amount of CO that
2
would have the same global warming potential (GWP)
3.4
charging factor
ratio between amount of Ah recharged into the battery and the prior discharged amount of Ah from
the battery
Note 1 to entry: Typically, the charge factor for lead acid batteries is in the range of 1,02 to 1,25.
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ISO 23308-1:2020(E)

3.5
power battery factor
PBF
factor that gives the ratio between the battery capacity and the electrical power taken from the battery
3.6
synthetic discharge cycle
typical battery discharge profile that mirrors the actual energy consumption of electric trucks during
a test cycle
4 Test conditions
4.1 General
The following test conditions ensure that the measurement of power consumption is performed in a
similar and comparable way.
4.2 Test equipment
4.2.1 Test area
The test area shall be a flat and smooth area with a hard, clean and dry surface made of concrete,
asphalt or equivalent. The test course shall have no more than 2 % slope in any direction of travel.
4.2.2 Test track
For truck type specific information, see the relevant part of the ISO 23308 series.
4.2.3 Test load and / or towing capacity
Unless it is otherwise stated in the specific part of the ISO 23308 series, the test load shall be
equal to 70 % of the rated load and standard load centre distance of the truck, in accordance with
ISO 3691-1:2011, A.2, or ISO 3691-2:2016, A.1 and A.3.
Tractors shall tow with a force according to 70 % of the rated drawbar pull, as defined in
ISO 3691-1:2011, A.3.
Burden-carriers shall be laden with 70 % of the maximum payload, as defined by the manufacturer.
4.3 Truck conditions
The truck to be tested shall be a sample that is representative of series production. For all parts of the
truck, with effect to the energy consumption, a run-in time of up to 100 h is permissible. The run-in
time shall be documented.
The truck to be tested shall be in a safe and functional state. All equipment attached shall be in
accordance to the specification of the manufacturer of the truck.
The set-up of the truck (e.g. software parameters) shall be available as per the manufacturer's
specification. This requirement means that the truck performance as specified is achievable (e.g. driving
and lifting speed, acceleration) and all software settings are commercially available to the customer.
NOTE For instance, the test driver can adapt the maximum driving speed to achieve the number of cycles
per hour.
The test truck shall be fitted with new tyres (maximum 10 % of tread wear) which shall comply with
the specifications of the manufacturer of the truck. Pneumatic tyres shall be inflated to their correct
pressure specified by the truck manufacturer or by default from the tire manufacturer.
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ISO 23308-1:2020(E)

The fuel tanks of internal combustion engine trucks shall be filled to the maximum specified level prior
to the warm up period. All other tanks shall be filled to their correct operating levels, if applicable.
If the test is to be performed on a sample that is representative for a range of trucks with the same
rated capacity but different lift heights, the test shall be carried out on the truck with the specification
according to ISO 3691-1:2011, A.2.1. For trucks covered by ISO 3691-2, the specific requirements of the
applicable part of the ISO 23308 series shall apply.
For trucks covered by ISO 3691-1, the specified lift height shall be at least the standard lift height
according to ISO 3691-1:2011, A.2.2. The truck’s specified lift height shall allow the measurement
procedures as defined in the specific part of the ISO 23308 series.
If the test is to be performed on a sample that is representative for a range of trucks with the same
rated capacity and the lift height is lower than the lift height that is specified in ISO 3691-1:2011, A.2.1
and A.2.2, the test shall be carried out on the truck with the greatest lift height.
If the test is to be performed on a sample representative of a range of electric trucks with the option
of different battery capacities, the test shall be carried out on the truck with the standard battery/
batteries according to the data sheet of the manufacturer.
4.4 Environmental conditions
The measurement shall be carried out at an environmental temperature range between 5 °C and 35 °C.
The truck in test configuration shall be at operating temperature.
A minimum warm-up period of 10 min is required for the laden truck, before the test starts.
4.5 Truck maintenance
IC-trucks with emissions control systems that can require cleaning or regeneration of the emission
control device shall remain within manufacturer recommended parameters throughout the test. It is
allowed to block automatic regenerating of the emission control device during the test.
Engines with other emissions control systems utilizing additional reagents/materials shall remain
within the parameters recommended by the manufacturer throughout the test.
4.6 Battery condition
Battery efficiencies are influenced by many factors, e.g. cell technology, cell type, cell design and
geometry. Therefore, the battery efficiency as stated in 6.2.2 is representative for the tested battery
type/battery manufacturer.
If the battery technology requires any energy consuming auxiliary device, e.g. battery management
system, controller, cooling or heating, this shall be included in the test.
The battery shall be charged to the rated capacity prior to the respective test. When tests require
discharging to the rated minimum capacity of the battery, this shall be determined by one of the
following methods.
a) Lead-acid batteries voltage: the battery is discharged if the voltage is less than or equal to 1,6 V/cell
(according to IEC 60254-1 for discharge current I1).
b) Lead-acid rated capacity: the battery is discharged if 80 % of the rated capacity is taken from
the battery during the test. Recuperation may be considered by calculating with 75 % of the
recuperated current over time.
c) Other technologies: discharge criteria are defined by the battery manufacturer. This criterion shall
be consistent with all other specification provided with the battery type, e.g. identical life time and
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ISO 23308-1:2020(E)

life cycle characteristic based on endurance tests. A discharge value given in energy (Wh) may be
used depending on the technology.
5 Measurement procedure
5.1 General
Subclauses 5.2 to 5.7 describe the measurement procedure that is applicable for trucks in general. For
specific information for different truck types, see the relevant part of the ISO 23308 series.
5.2 Operating sequence
Trucks shall operate according to the manufacturer's instruction handbook and the test specification
defined in the specific part of the ISO 23308 series with the load according to 4.2.3. Unless otherwise
stated in the specific part of the ISO 23308 series, pick- and place-cycles may be simulated without
depositing the load.
NOTE The test load can be secured.
The speed shall be so adapted as to obtain the specified number of cycles per hour. Unless otherwise
stated in the specific part of the ISO 23308 series, simultaneous operations are not permissible, all load
handling and travelling functions shall be operated separately.
For truck types that are not covered exhaustively by a specific part of the ISO 23308 series, an
appropriate sequence of operations shall be selected depending on the design in accordance with the
intended use of the truck.
5.3 Electric trucks
5.3.1 General
To determine the overall energy consumption of electric trucks the test shall consider:
— the overall efficiency of the truck, including motor (s), controller(s) and electrical installation;
— the efficiency of the battery/batteries;
— the efficiency of the battery charger.
Because the equipment of trucks with batteries and battery chargers is versatile, it is generally
necessary to differentiate between these elements.
Subclauses 5.3.2 to 5.3.4 define the procedure to determine the elements of the system efficiency.
5.3.2 Truck measurement
The battery of the truck shall be charged to the rated capacity prior to the warm-up period.
The measurement of the energy consumption shall start at the first test cycle. The warm-up period
shall be excluded from the measurement.
The energy consumption shall be given in terms of the electrical energy that is required for 1 h
performing the operating sequence, in kWh/h. This measurement can be done by continuous
measurement of voltage and current during the test [see Formula (1)].
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ISO 23308-1:2020(E)

The measurement of voltage and current shall be performed at the connector of the truck and the
traction battery.
T
EU= ()tf∗∗It()∗dt (1)
truckb∫ attbatt
0
where
E is the energy taken from the battery during the test in Wh;
truck
U is the battery voltage in V;
batt
I is the battery current in A;
batt
dt is the differential (measurement over time);
T is the test duration;
f is the discharge/charge factor with f = 1 for I ≥ 0; and f = 0,75 for I < 0.
batt batt
NOTE 1 I < 0 represents recuperation. The factor f = 0,75 refers to the majority of traction batteries, namely
batt
lead-acid batteries.
NOTE 2 The factor f differs for other battery technologies.
If the power consumption is determined by measuring electric charge in Ah, the power consumption
shall be calculated by multiplication with the nominal battery voltage.
If the determination of the battery efficiency should be included in the truck measurement procedure,
the measurement cycle shall start with a battery charged to its rated capacity and shall continue until
the battery is discharged to the rated minimum capacity (see 4.6).
5.3.3 Battery efficiency
The battery efficiency consists of two elements that generate power loss:
— the energy flow to the truck (energy taken by the truck from the battery);
— the energy flow from the charger to the battery (energy for complete recharging of the discharged
battery).
NOTE The efficiency varies depending on the battery charging status, the current when discharging, the
current and method when charging, the battery temperature and the battery type.
The overall efficiency of the battery shall be determined by:
— direct measurement of current and voltage during discharging the battery by performing the truck
measurement according to 5.3.2 until the battery is discharged to the rated minimum capacity (see
last paragraph of 5.3.2 and 4.6), and during recharging the battery (see 5.3.4);
— direct measurement of current and voltage during discharging the battery by performing the
synthetic discharge cycle (in accordance with Annex A), until the battery is discharged to the rated
minimum capacity (see last paragraph of 5.3.2 and 4.6) and during recharging the battery (see
1)
5.3.4 ); or
— using defined battery specific values that are verified to be suitable to determine the battery
efficiency for lead acid traction batteries used in a truck (in accordance with Annex B).
1) The synthetic discharge cycle can be used to determine the efficiency of all kind of batteries.
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ISO 23308-1:2020(E)

5.3.4 Charger efficiency
The overall efficiency of the charger shall be determined:
— in combination with the truck measurement according to 5.3.2;
— after the battery efficiency evaluation according to 5.3.3; or
— by taking into account information of the charger efficiency operating at its optimum operating
point (see Annex B).
If a test is performed, the current and voltage at the charger's terminals shall be continuously measured
against time to allow calculation of the charger efficiency.
From this test, the charger efficiency is calculated with Formula (2):
E
ch
η = (2)
ch
E
grid
where
η is the charger efficiency;
ch
E is the energy delivered to the battery in Wh;
ch
E is the energy withdrawn from grid supply in Wh.
grid
In addition to the efficiency value, information regarding the power factor should be given in the data
sheet and on the type plate of the charger.
The power factor shall be determined for the rated operating point. If this is not possible, the power
factor may be determined at 80 % of the rated power. In this case, information should be given in the
data sheet.
5.4 Internal combustion (IC)-trucks
The measurement of the energy consumption shall start at the first test cycle. The warm-up period
shall be excluded from the measurement.
The energy consumption of diesel and gasoline driven trucks shall be given in fuel per hour (l/h) or, for
trucks powered by gas (LPG) or natural gas (CNG), in gas consumption per hour (kg/h).
The LPG quality shall be in accordance to EN 589.
The CNG quality shall be in accordance to ISO 15500-1.
3
Diesel fuel shall be determined by weight, calculated for 15 °C. The density of the fuel of 830 kg/m
shall be used, which corresponds with the average as defined in EN 590.
5.5 Hybrid trucks
Hybrid trucks shall be tested according to 5.4.
After the test, the energy stored in accumulators (e.g. electrical, pneumatic or hydraulic) shall not be
less than before starting the test.
NOTE Starter batteries are not subject to this requirement.
5.6 Measurement accuracy
Suitable measurement equipment shall be selected.
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ISO 23308-1:2020(E)

The following tolerances or accuracies of the measurement equipment shall be taken into consideration.
All measuring equipment shall have an accuracy of ±2 % maximum. The time measuring
...