ISO 8856:2014

INTERNATIONAL ISO
STANDARD 8856
Third edition
2014-01-15
Road vehicles — Electrical
performance of starter motors — Test
methods and general requirements
Véhicules routiers — Caractéristiques électriques des démarreurs —
Méthodes d’essai et conditions générales
Reference number
©
ISO 2014
© ISO 2014
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ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Terms and definitions . 1
3 Test conditions . 2
3.1 Temperature . 2
3.2 Measurement accuracy . 2
3.3 Voltage/current characteristic of starter motor power supply . 2
3.4 Preparation of test samples . 3
4 Test benches . 3
4.1 General . 3
4.2 Type 1 test bench . 4
4.3 Type 2 test bench . 4
5 Test method . 6
5.1 General . 6
5.2 Test procedure . 6
6 Measurement correction . 7
6.1 General . 7
6.2 Correction of torque . 7
6.3 Correction of rotational frequency with temperature . 9
7 Presentation of results .10
7.1 Power output and efficiency calculation .10
7.2 Graphic presentation of starter motor characteristic curves .10
7.3 Change of voltage/current characteristic .10
Foreword
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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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).
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to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 3, Electrical
and electronic equipment.
This third edition cancels and replaces the second edition (ISO 8856:1995), which has been technically
revised. It also incorporates the Amendment ISO 8856:1995/Amd1:1997.
iv © ISO 2014 – All rights reserved

INTERNATIONAL STANDARD ISO 8856:2014(E)
Road vehicles — Electrical performance of starter motors
— Test methods and general requirements
1 Scope
This International Standard lays down test methods and general requirements for the determination of
the electrical characteristics of DC starter motors intended to start internal combustion engines of road
vehicles.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
lock torque
torque of starter motor at the pinion with the armature shaft locked (no rotation)
Note 1 to entry: It is expressed in Nm.
2.2
nominal power
P
nom
power declared by the starter motor manufacturer corresponding to the maximum power output at the
reference temperature when determined in accordance with this International Standard
Note 1 to entry: It is expressed in W.
2.3
power output
P
power derived from measurements of torque and rotational frequency of the motor pinion shaft
Note 1 to entry: It is expressed in W.
2.4
power supply
battery or battery simulation device which delivers a voltage/current characteristic as defined in this
International Standard
2.5
reference temperature
temperature at which the performance curves and nominal power shall be reported
Note 1 to entry: Reference temperature is expressed in °C.
Note 2 to entry: It is equal to 20 °C.
2.6
total resistance of starter motor
R
S
resistance value of the terminal voltage, see Figure 2, divided by the starter motor current (steady state
current of solenoid included)
Note 1 to entry: It is expressed in Ω.
2.7
total resistance of power supply at starter motor terminals
R
BL
sum of power supply and external line resistance
Note 1 to entry: It is expressed in Ω.
3 Test conditions
3.1 Temperature
3.1.1 Test method A — Continuous mode method
Ensure that all parts of the starter motor are at the same, registered temperature.
To avoid temperature corrections, the starter motor can be preconditioned at (20 ± 2) °C.
3.1.2 Test method B — Discrete point method
Ensure that all parts of the starter motor are at the same, registered temperature.
To avoid temperature corrections, the starter motor can be preconditioned at (20 ± 2) °C.
3.1.3 Test method C — Continuous mode method at cold cranking temperature
The starter motor shall be preconditioned at a specified cold cranking temperature as agreed between
starter motor manufacturer and engine manufacturer (e.g. −25 °C ± 2 °C).
3.2 Measurement accuracy
The overall capability of the test equipment shall enable the parameters to be measured within the
accuracy shown in Table 1. This requirement shall be respected through the whole test procedure. The
target accuracy should be used for new test equipment.
Table 1 — Measurement accuracy
Parameter Accuracy Target accuracy
Current ±1 % ±0,5 %
Voltage ±1 % ±0,5 %
Rotational frequency ±2 % ±1 %
Torque ±2 % ±1 %
Temperature ±2 K ±2 K
3.3 Voltage/current characteristic of starter motor power supply
The voltage/current characteristic of starter motor power supply is a sloping straight line (see Figure 1).
The line is defined at 20 °C either by two pairs of values [(U , I ) and (U , I )], or by one pair of values (U,
1 1 2 2
I) and the internal resistance of the starter motor power supply.
The voltage values (U and U ) shall be measured at the starter motor terminals.
1 2
The voltage/current characteristic shall be selected from Table 2 without exceeding the values stated by
the starter motor manufacturer.
If required, other voltage/current characteristics can be used as agreed between the starter motor
manufacturer and the vehicle manufacturer.
2 © ISO 2014 – All rights reserved

Key
1 at 20 °C
Figure 1 — Voltage/current characteristic of starter motor power supply
3.4 Preparation of test samples
For new starter motors, it is necessary to perform a run-in procedure in order to ensure a stable
performance. One example for such a run-in procedure is described below.
Starter motor should be run-in with 40 cycles as follows:
a) 2 s running at a torque equal to 25 % of the lock torque value;
b) 13 s rest.
Cooling is permitted during this preparation. The lock torque shall be measured using an appropriate
power supply (see Table 2).
Other preparation test conditions can be used if equivalent or better effect on stabilization of starter
performance is confirmed.
4 Test benches
4.1 General
There are two types of test bench which can be used.
On either type, torque shall be measured either directly as the reaction torque of the starter motor, or
at the drive gear shaft.
4.2 Type 1 test bench
The test bench in Figure 2 allows performance measurements to be taken by engaging the pinion with
a drive gear, either the ring gear assembly or suitable alternative. The backlash between the pinion and
the drive gear teeth shall be in accordance with the starter motor manufacturer’s recommendations.
Key
1 starter motor
2 brake/variable load
3 solenoid
4 starter motor terminals
5 starter motor power supply
6, 7 torque measurement
8 rotational frequency measurement
9 drive gear
Figure 2 — Type 1 test bench
4.3 Type 2 test bench
The test bench in Figure 3 permits direct measurement of the starter motor at the pinion or armature
shaft. The starter motor shall be coupled to the test device coaxially through a suitable coupling. The
drive end shield of a nose-type starter motor can be replaced by a special bearing bracket to permit
coupling to the starter motor shaft.
4 © ISO 2014 – All rights reserved

Key
1 brake/variable load
2 coupling
3 starter motor
4 solenoid
5 starter motor terminals
6 starter motor power supply
7, 8 torque measurement
9 rotational frequency measurement
Figure 3 — Type 2 test bench
Table 2 — Voltage/current characteristic of starter motor supply for starter motor testing
Voltage/current characteristic
Voltage/current Nominal at 20 °C Suggested nominal power of
characteristic voltage starter motor
U I U I R
1 1 2 2 BL
number V kW
V A V A mΩ
1 400 15 P ≤ 1,7
nom
2 600 10 1 < P ≤ 2,5
nom
3 800 7,5 1,5 < P ≤ 3,4
nom
4 1 000 6 1,5 < P ≤ 4,2
nom
12 12 0 6
5 1 200 5 2,5 < P ≤ 5
nom
6 1 500 4 3 < P ≤ 6,3
nom
7 2 000 3 3,8 < P ≤ 8,4
nom
8 3 000 2 P > 5
nom
9 600 20 P ≤ 5
nom
10 800 15 3 < P ≤ 6,7
nom
11 1 000 12 4 < P ≤ 8,4
nom
12 1 200 10 5 < P ≤ 10
nom
24 24 0 12
13 1 500 8 6 < P ≤ 12,6
nom
14 1 700 7,06 7,5 < P ≤ 14,3
nom
15 2 000 6 8,3 < P ≤ 16,8
nom
16 2 400 5 P > 10
nom
5 Test method
5.1 General
Test method A or B shal
...