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Pack Level Shock and Vibration Requirements
1. Objective/Purpose:
The purpose of the testing is to stress a rechargeable energy storage system from both an electrical and mechanical
standpoint to verify that there are no safety issues that arise from mechanical shock, vibration and temperature excursions
in real world applications.
2. Risk areas and Safety needs:
During a normal operation of a vehicle, vehicle’s components are subjected to extreme environments such as vibration,
shock and temperature. The REESS is susceptible to such environments which could develop internal mechanical failures
resulting in a safety event such as thermal runaway. This requirement evaluates the performance of the REESS by
subjecting it to a series of shock tests and vibration under extreme temperature cycling.
3. Performance criteria:
The REESS is subjected to the following sequential tests:
Step 1 Sine Sweep Test
Step 2 Mechanical Shock Test
Step 3 Sine Sweep Test (repeated)
Step 4 Random Vibration Test
Step 5 Sine Sweep Test (repeated)
After each test, the RESS is evaluated under the following criteria:
a. Isolation Resistance: 0.5 Mohm or greater
b. Temperature: Any rise in temperature greater than 10°C
c. Voltage Drift (change in the state of charge): Any change in the state of charge greater than 5% over the course of
the test. This can be up to complete loss of potential.
d. Structural Damage: Any abnormal deformations, cracks, or any other signs of physical damage to the DUT which
can be found through visual examination methods. Any shifts mechanical resonances found between pre and post
test may indicate structural damage and thus any difference greater than 10% in frequency or amplitude level of
found resonance points from sine sweep test performed pre and post random vibration and mechanical shock tests
shall require internal inspection of the device under test.
e. Functional Charge/Discharge Sequence: A change in capacity/discharge duration or charging duration, greater
than 10% when compared to pre-test values shall signify that test criteria is not met.
4. Test procedures: Test procedures included in an appendix.
Test Sequence
Prior to the start of the vibration testing, the thermal cycle profile must be developed. The procedure for this
development is detailed in EVS-06-37. Once the thermal cycle development procedure is complete, a full
charge/discharge cycle is to be performed on the device under test. Where applicable, the charge/discharge cycle as
prescribed from the manufacturer is to be followed. If this information is not available at the time of testing, and then
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a C/3 charge/discharge rate may be used as the default. Upon the completion of the cycle, the State of Charge (SOC)
shall be set to 100%.
The mounting and support structure (fixture) of the DUT shall be as similar as possible to the manufacturer’s
recommended installation requirements for all vibration and mechanical shock tests. The fixture is to keep the DUT
from being in direct contact with any point of the vibration exciter. The fixture shall hold the DUT in a manner as to,
at minimum, have the same level of rigidity as the mounting of the DUT in vehicle. The fixture shall not have any
resonances (as defined in section 7.2) below 50 Hz, the Test Fixture is to be designed and built in a manner as to
allow it to be removed from the vibration exciter in order to reposition the DUT in each of the three orthogonal axes,
without having to remove the DUT from the fixture itself.
The vibration test will be separated into five (5) separate test steps, to be tested sequentially.
The four (5) steps are as follows:
Step 1 Sine Sweep
Step 2 Mechanical Shock Test
Step 3 Sine Sweep (repeated)
Step 4 Random Vibration Test
Step 5 Sine Sweep (repeated)
Step 1: Sine Sweep: The purpose of this test is to find any resonances in the DUT which could lead to potential
mechanical failure under normal operating vibration conditions. As found in IEC 60068 2-64, it is determined that a
resonance point is any excitation of the DUT over two times the input excitation from the Vibration stand. The Sine
Sweep Profile is to be conducted in 3 orthogonal axes, referred to as X, Y, Z. Please refer to Appendix A for
Vibration controller setup. The resolution required for all vibration parameters could not be determined though
examination of other standards thus the value will need to be verified during trial test runs.
Sine Sweep Profile
Tolerance bands: ± 6dB
Amplitude:
Frequency Range:
Sweep Rate:
1G
10-1000 Hz.
1 Octave/min
Excitation of a factor of 2 or greater beyond the input level will be considered a resonance node.
Step 2: Mechanical Shock Test: The purpose of this test is to subject the DUT to shock levels to ensure proper
Isolation measures between the energy cells, DUT enclosure, and any other devices placed within DUT. The
Mechanical Shock profile is to be run in three orthogonal axes, referred to as X, Y, Z. While performing the shocks,
allow a minimum of 30 second dwell period between pulses to allow the DUT to return to a steady state condition.
Refer to Table 6.5.5 for details of the Mechanical Shock profile.
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Mechanical shock profile
Acceleratio Du ration
n
G
mS
Pulse Type
Number of P ulses
25
Half Sine
3/axis both positive and negative
directions for a total of 18
15
Tolerance of +/- 5G (20% of peak acceleration) within the 15ms nominal pulse duration.
Step 3: Sine Sweep (repeated): The purpose of this test is to ensure that resonances in the DUT documented during
the Step 1 Sine Sweep test have not changed as a result of the Random Mechanical Shock test, indicating a potential
mechanical change or damage within the DUT. These profiles are to be the same as used for step 1.
Step 4: Random Vibration Test: The purpose of this test is to subject the DUT to a level of vibration to ensure that
the DUT can be considered safe for use in a typical light vehicle transportation scenario. Temperature profile is to be
run in conjunction with the Random Vibration test. The Random Vibration profile is to be run in three orthogonal
axes, referred to as X, Y, Z. Refer to Table 6.5.3 for the random vibrations profile, and Table 6.5.4 for the
companying Temperature profile. The duration of the random vibration test will be dependent upon the stabilization
time of the DUT which is to be found through the use of the thermal cycle profile development procedure which is
detailed in Section 6.4.
Random Vibration profile
Segment Length Elapsed Time
0
0
1 Hour
1 hour
ST+1 Hour
2+ hours
1 Hour
3+ hours
ST+1 Hour
4+ hours
1 Hour
5+ hours
ST+1 Hour
6+ hours
1 Hour
7+ hours
Temperature
25
(°C)
-40
-40
85
85
50
50
25
Humidity (%RH)
NA
NA
NA
45
45
85
85
NA
Temperature Cycling
Step 5: Sine Sweep (repeated): The purpose of this test is to ensure that resonances in the DUT documented during
the Step 1 Sine Sweep test have not changed as a result of the Random Vibration test, indicating a potential
mechanical change or damage within the DUT. These profiles are to be the same as used for Step 1.
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During all steps of testing the vibration and shock excitation is to be monitored through the use of accelerometers.
Size and type of accelerometer can be determined by test facility based on size of the DUT or general availability.
Temperature compensated accelerometers are recommended, however at minimum the accelerometers utilized are to
have an operating range suitable to guarantee the accuracy of the sensor. For all outlined tests, a minimum of four (4)
accelerometers are to be used per DUT and placed in the following manner:
-Two (2) accelerometers to be placed on the upper rigid corners diagonally across
from one another in opposite corners
-One (1) on fixture mounting support as far from exciter as possible
-One (1) on centerline axis of the test mounting plate or shaker slip table where
applicable.
Both the accelerometer on the mounting support and the centerline of the mounting plate or slip table are to be used
as the control accelerometers, controlled as an average of the two locations. The locations of the accelerometers are
to be recorded and photographed in order to facilitate test repeatability. If it is unfeasible to place accelerometers in
these positions, alternate locations maybe selected, recorded and explained as to why the original locations were not
utilized.
5. Pass/fail criteria:
a. Isolation Resistance: 0.5 Mohm or greater
b. Temperature: Any rise in temperature greater than 10°C
c. Voltage Drift (change in the state of charge): Any change in the state of charge greater than 5% over the course of
the test. This can be up to complete loss of potential.
d. Structural Damage: Any abnormal deformations, cracks, or any other signs of physical damage to the DUT which
can be found through visual examination methods. Any shifts mechanical resonances found between pre and post
test may indicate structural damage and thus any difference greater than 10% in frequency or amplitude level of
found resonance points from sine sweep test performed pre and post random vibration and mechanical shock tests
shall require internal inspection of the device under test.
e. Functional Charge/Discharge Sequence: A change in capacity/discharge duration or charging duration, greater
than 10% when compared to pre-test values shall signify that test criteria is not met.
6. Justification:
Purpose of this test is to simulate potential degradation of the REESS from in-use:
Step 1, 3 and 5 - Sine sweep: A Sine sweep test is required as it is the common method used in automotive
testing to quickly determine resonances within a DUT. Mechanical resonances are the tendency of a mechanical system to
absorb more energy when the frequency of its oscillations matches the system's natural frequency of vibration than it does
at other frequencies. It may cause violent swaying motions and even catastrophic failure in improperly constructed RESS
resulting in very dangerous and life threatening situations. The parameters were selected upon guidance from ISO 167503 and EC60068 2-64:2008. The selection of parameters are a result of prior experience as it is found to be common
practice in automotive testing based on previous test experience. It is determined that a resonance point is any
excitation of the DUT over two times the input excitation from the vibration stand.
Upon completion of the random vibration profile and mechanical shock, the sine sweep profile is to be repeated.
This allows for comparisons to be made of the condition of the DUT as a result of the other vibration/shock profiles.
This allows for a change in the mechanical resonances to be measured, thus changes to the structure of the DUT
which cannot be visually identified may be found. The rationale for the level at which the fixture is to be free of any
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resonances below 50 Hz. was derived from SAE J2464, this standard is intended to test the same type of devices,
thus it was considered a reasonable level to eliminate unintended excessive mechanical stress to the DUT.
Step 2 - Mechanical Shock Test: The parameters were selected to emulate the test parameters found in the
standards listed in Table 7.1, specifically GMW 3172, ISO 16750- 3:2003, and SAE J2464. the parameters selected, 25g
at 15 ms and 18 total pulses, were selected as the levels in GMW 3172 and SAE J2464 simulate the levels required for
automotive testing, and is considered to be a more common industry standard. Purpose of this test is to simulate potential
degradation from in-vehicle use. Within the standard GMW 3172 there are also higher shock levels but these are to
simulate collision shock which was considered to be unreasonable for testing the long term effects of vibration and shock
on the DUTs.
Step 4 - Random Vibration Test + thermal cycling: the parameters for this profile were created using the
following standards as guidance: ISO 16750-3, GMW 3172, and ISO 12405-1, in order to simulate what would
reasonably considered long term degradation effects.
The overall amplitude levels were reduced to from those found in ISO 16750-3, The reduction of the profile levels
are to bring the profile in line with common road profiles performed for specific test requests and as the standards
referenced are themselves derivatives of conglomerate road inputs.
The purpose of including temperature and humidity stress into the test procedure is to create accelerated degradation and
thermal fatigue to further expose potential problem areas with the DUT as well as to better evaluate the device’s resistance
to the imposed vibration profile while being stressed to described temperature/humidity extremes and gradients. Vehicle
vibration stress can occur together with extremely low or high temperatures, thus it is reasonable to include this stress type
when evaluating the safety of the device. The three temperature levels along with the corresponding humidity levels, of 40°C, 85°C, and 50°C /85% were selected based on levels from the test standard GMW 3172 which references these
temperatures for devices which would be in any location in/on the vehicle, (shielded from conventional engine heat, if
applicable). These values were specifically selected for this specification as this is a common set of levels used in the
automotive industry.
In certain cases, the maximum operating limit of the DUT may be exceeded at 85°C, however the DUT is not actively
charged / discharged during the Temperature cycling portion of this test; the maximum limit of that device should be used,
as a safety precaution. In order to ensure proper thermal loading during the vibration testing, independent on the
mass and shielding of a specific device under test, a thermal cycle profile development procedures included. This
development procedure was created with guidance from similar tests specified in ISO 16750-4, as well as GMW 3172.
The stabilization temperature tolerance of 3% was utilized based on the tolerances found in these specifications. As a
DUT with smaller mass will exhibit faster temperature transitions, the thermal shock will be higher the smaller the
thermal load of the DUT. A larger DUT however, will exhibit slower temperature transitions, thus will experience a
longer vibration duration. This trade-off allows for any size DUT exposure to vibration throughout the temperature
transitions, with a minimum guaranteed duration at each temperature extreme.
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