UN/SCETDG/
COMMITTEE OF EXPERTS ON THE TRANSPORT OF
DANGEROUS GOODS AND ON THE GLOBALLY
HARMONIZED SYSTEM OF CLASSIFICATION
AND LABELLING OF CHEMICALS
Working Group on the Transport of
Large Format Lithium Batteries
3rd Session
Washington, D.C. USA, September 2014
LISTING, CLASSIFICATION AND PACKING
Testing of Large Lithium Batteries and Lithium Battery Assemblies
Transmitted by the Council on the Safe Transportation of Hazardous Articles (COSTHA)
Introduction
1. Among COSTHA’s membership is a group identified as the North American Automotive
HAZMAT Action Committee (NAAHAC). Participants in this committee include 12
automobile manufacturers from around the world but operate in the United States. Additionally,
COSTHA counts five (5) additional members who are direct suppliers to the automotive
industry, providing numerous materials and devices for production support.
2. The Sub-Committee has recognized the need to review the UN Manual of Tests and
Criteria, specifically Section 38.3 as they relate to the transport of large lithium batteries and
assemblies. COSTHA supports the efforts of the Sub-Committee in this endeavour and would
like to present data to further the discussion.
Discussion
3. The concern over the testing of large format lithium ion batteries was discussed at length
during the UN Informal Working Group on Batteries held in 2008-2010. During this meeting,
COSTHA and member organizations provided presentations detailing the concerns facing the
gasoline-electric hybrid vehicle, hydrogen fuel cell hybrid-electric vehicle, and pure battery
electric vehicle manufacturers and suppliers with regards to the testing of these “large” batteries.
Specifically, the UN Test T4 was identified as posing significant design issues for the battery
manufacturers yet was not modified as a result of the previous Working Group conclusions.
4. In May of 2010, COSTHA presented a paper discussing the physics of the T.4. The paper
was well received but no formal proposals resulted directly from the effort. This document
recounts much of the technical data presented in that paper. However, based on discussions
since May 2010, including discussions at the first session of the UN Working Group on the
Transport of Large Format Lithium Batteries, COSTHA has been proposing changes to the T.4
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test based upon a sliding scale of mass vs. acceleration. This concept was discussed and
development was encouraged at the October, 2013 UN Lithium Battery Working Group meeting
held in Washington, D.C.
5.
Test 4 currently requires cells and batteries to be subjected to a half-sine shock of peak
acceleration of 150 gn and a pulse duration of 6 milliseconds. The shock test includes 3 shocks
in the positive and 3 shocks in the negative direction in 3 mutually perpendicular mounting
positions of the cell or battery for a total of 18 shocks per battery. For large format batteries
(mass greater than 12 kg), the peak acceleration shall be 50 gn and a pulse duration of 11
milliseconds.
6.
Gasoline-hybrid vehicle traction batteries typically range today between 14 kg and 80 kg
with full-electric vehicle batteries often exceeding 100 kg mass. Their capacity is typically 300
Wh to 2,500 Wh for hybrid batteries and in excess of 6,200 Wh for full-electric vehicle batteries,
with Plug-In Hybrid Electric Vehicle (PHEV) batteries occupying any capacity and mass in
between.
Applied Forces for Different Masses
7.
Current Test 4 force and acceleration conditions are inappropriate for these hybrid or
electric vehicle (HEV) battery assemblies as well as other large format batteries, and most
importantly, the forces required for HEV battery assemblies during the testing are well beyond
any forces that would be encountered during transport.
8.
The T4 Shock Test is an impact test, with the governing equation:
F = m*a
This formula can be further manipulated:
F = m * dv/dt
F * dt = m * dv
Where:
F = applied force measured in Newtons (N)
dt = time the force is applied (s)
m = mass of the test part (kg)
dv = change in velocity of the test part while the force is applied (m/s)
a = acceleration (m/s2)
9.
It is apparent that both the maximum acceleration and mass are fixed, this results in
varying the force on the test mass. However, larger batteries may not actually be subjected to
higher impact forces in transportation.
10.
A graph of the current UN 38.3 T4 graph of Force vs mass is shown in Figure 1:
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Figure 1 Curent UN T4 Test Forces
11. Concerns about this curve include the following:
a) The force necessary to test a large lithium ion battery is significantly higher than for
smaller batteries.
b) As shown in previous COSTHA presentations, the force applied to larger lithium
batteries is not proportional. i.e. 10x mass results in >10x Force.
c) Is it rational to test an 11.99 kg battery at 17k N (150 gn) and a 12.01 kg battery at ~6k N
(50 gn)?
Proposal 1
12. COSTHA proposes the Working Group consider the following changes to the T.4 test:
13. COSTHA recommends revising the conditions of the T4 test to address the significant
amplification of force in testing large format batteries. Instead of setting the acceleration (gn) as
a constant (150 gn for <12 kg batteries and 50 gn for >12 kg batteries), we recommend that the
shock acceleration be scaled for larger batteries. One concept would hold force constant from
50gn /12kg. COSTHA proposes that the peak acceleration be varied based on the mass of the
battery and the force of the 12kg, 50 gn shock profile per the formula below:
𝐹𝑜𝑟𝑐𝑒
Peak Acceleration (gn) = 𝑚𝑎𝑠𝑠 =
50 𝑔𝑛 ∗12 𝑘𝑔
𝑏𝑎𝑡𝑡𝑒𝑟𝑦 𝑚𝑎𝑠
=
600 𝑔𝑛 𝑘𝑔
𝑏𝑎𝑡𝑡𝑒𝑟𝑦 𝑚𝑎𝑠𝑠 (𝑘𝑔)
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14. To offset the change in peak acceleration for the mass correction noted in 13 above, the
pulse duration should be adjusted such that the total energy expended during the shock pulse is
equivalent to the energy of the 12kg, 50 gn shock. The following formula approximates the
energy for the 50 gn pulse at 12.0 kg.
1
Energy = 2 𝑚𝑣 2
Change in Velocity for Acceleration Pulse =
𝐸𝑛𝑒𝑟𝑔𝑦 = 2 𝑥 𝑚𝑎𝑠𝑠 𝑥 (
2 𝑥 𝑃𝑒𝑎𝑘 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 ∗ 𝑃𝑢𝑙𝑠𝑒 𝑇𝑖𝑚𝑒
𝜋
𝑃𝑒𝑎𝑘 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 ∗ 𝑃𝑢𝑙𝑠𝑒 𝑇𝑖𝑚𝑒 2
)
𝜋
For 50 gn, 12 kg:
𝐸𝑛𝑒𝑟𝑔𝑦 = 2 𝑥 12 𝑥 (
50∗9.81 ∗ .011 2
) = 70.8 Joules
𝜋
When the peak amplitude is changed the pulse duration must be adjusted to maintain the total
energy of the pulse. The pulse duration is based on the 50 gn, 12 kg shock profile and calculated
per the formula below:
𝐸𝑛𝑒𝑟𝑔𝑦 (𝑗𝑜𝑢𝑙𝑒)
𝜋
𝑃𝑢𝑙𝑠𝑒 𝑇𝑖𝑚𝑒 = √(
)𝑥
𝑚
2 𝑥 𝑚𝑎𝑠𝑠 (𝑘𝑔)
𝑃𝑒𝑎𝑘 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 ( 2 )
𝑠
For example, a 15 kg battery would require a 40 gn shock. The acceleration pulse duration
necessary to maintain the 50 gn, 12 kg shock energy is:
70.8
𝑃𝑢𝑙𝑠𝑒 𝑇𝑖𝑚𝑒 = √(2 𝑥 15) 𝑥
𝜋
40∗9.81
= 12.3 mSec
15. Testing labs have requested to constrain the pulse duration to a maximum of 25 milliseconds
to support their testing capabilities. In order to support this request of the test labs, the minimum
peak acceleration should be held at 10 gn (at approximately 60 kg). The pulse time calculation
will maintain the constant energy of the shock pulse.
16. The resulting accelerations vs. mass for UN 38.3 T4 concepts are shown in Figure 2. The
resulting forces vs. mass for the concepts are shown in Figure 3. Figure 4 shows the Energy of
the corresponding shock pulses using the formulas described above. As can be seen in these
figures, the current discontinuity between large and small batteries (reference paragraph 11 c.)
can be eliminated following the energy relationship to a battery mass of approximately 4 kg.
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Sliding Scale Proposal for UN Shock Test
160
Current T4 (g)
New Proposal
140.0
Duration (mS)
140
120.0
120
100.0
80.0
80
60.0
60
40.0
40
20.0
20
0
0.0
0 4kg
20
40
60
80
100
mass (kg)
Figure 2 - Shock Test Proposal
Figure 3 - UN Shock Test Forces Comparison
120
140
Time (mS)
Acceleration (g)
100
UN/SCETDG/
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Figure 4 - Energy of Shock Pulse
17. For the proposed shock profile, peak acceleration is based on the battery mass and the force
achieved at 50 gn, 12 kg threshold is held constant through the testing. As the peak acceleration
varies for battery mass, the duration of the shock pulse shall be adjusted such that the same
energy expended in the 50 gn , 12 kg shock pulse is uniform throughout. The maximum
acceleration shall be 150 gn and the maximum pulse width at 150 gn shall be 6 mSec at
approximately 4 kg.
18. The text of T.4 would be modified to reflect these changes:
PROPOSAL 1 – Uniform Shock Energy for Lithium Batteries
This proposal is intended to address consistency of the shock energy pulse
38.3.4.4 Test T.4: Shock
38.3.4.4.1 Purpose
This test simulates possible assesses robustness of cell and battery against
cumulative impacts during transport.
38.3.4.4.2 Test procedure
Test cells and batteries shall be secured to the testing machine by means of a
rigid mount which will support all mounting surfaces of each test battery. Each cell or battery
shall be subjected to a half-sine shock of peak acceleration of 150 gn and pulse duration of 6
milliseconds. Large cells and large batteries shall be subjected to a half-sine shock of peak
UN/SCETDG/
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acceleration of 50 gn and pulse duration of 11 milliseconds. Each cell or battery shall be
subjected to three shocks in the positive direction followed by three shocks in the negative
direction of three mutually perpendicular mounting positions of the cell or battery for a total of
18 shocks.
However, large cells and large batteries shall be subjected to a half-sine shock of peak
acceleration of 50 gn and pulse duration of 11 milliseconds. Each cell or battery is subjected to
three shocks in the positive direction followed by three shocks in the negative direction of each
of three mutually perpendicular mounting positions of the cell for a total of 18 shocks.
However, batteries shall be subjected to a half-sine shock of peak acceleration depending on the
mass of the battery. The pulse duration should be adjusted for the change in peak acceleration
such that the total energy of the shock pulse remains consistent. (Note: The peak acceleration
can be increased to minimize the pulse duration to accommodate specific test equipment
capability such that the total shock pulse energy remains consistent). The formulas below are
provided to calculate the appropriate peak acceleration and corresponding pulse width.
600 g kg
𝑛
Peak Acceleration (gn) ≥ 𝑏𝑎𝑡𝑡𝑒𝑟𝑦 𝑚𝑎𝑠𝑠
(𝑘𝑔)
0.32
35.3
Pulse duration (s) = 𝑃𝑒𝑎𝑘 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 𝑥√𝑏𝑎𝑡𝑡𝑒𝑟𝑦 𝑚𝑎𝑠𝑠
The minimum peak acceleration for any battery shall be 10 gn.
The maximum peak acceleration for any battery shall be 150 gn and the pulse duration at 150 gn
shall be 6 milliseconds.
The minimum peak acceleration for any test shall be 25 gn.
Each battery shall be subjected to three shocks in the positive direction followed by three shocks
in the negative direction of three mutually perpendicular mounting positions of the battery for a
total of 18 shocks.
Cells and batteries meet this requirement if there is no mass loss, no leakage, no venting, no
disassembly and no fire and if the open circuit voltage of each test cell or battery after testing is
not less than 90% of its voltage immediately prior to this procedure. The requirement related to
voltage is not applicable to test cells and batteries at fully discharged states.
PROPOSAL 2 – Uniform Shock Energy for Large Format Batteries Only
38.3.4.4
Test T.4: Shock
38.3.4.4.1 Purpose
This test simulates possible assesses robustness of cell and battery against
cumulative impacts during transport.
38.3.4.4.2 Test procedure
Test cells and batteries shall be secured to the testing machine by means of a
rigid mount which will support all mounting surfaces of each test battery. Each cell or battery
shall be subjected to a half-sine shock of peak acceleration of 150 gn and pulse duration of 6
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milliseconds. Large cells and large batteries shall be subjected to a half-sine shock of peak
acceleration of 50 gn and pulse duration of 11 milliseconds. Each cell or battery shall be
subjected to three shocks in the positive direction followed by three shocks in the negative
direction of three mutually perpendicular mounting positions of the cell or battery for a total of
18 shocks.
However, large cells and large batteries shall be subjected to a half-sine shock of peak
acceleration of 50 gn and pulse duration of 11 milliseconds. Each cell or battery is subjected to
three shocks in the positive direction followed by three shocks in the negative direction of each
of three mutually perpendicular mounting positions of the cell for a total of 18 shocks.
However, large batteries shall be subjected to a half-sine shock of peak acceleration depending
on the mass or battery. The pulse duration should be adjusted for the change in peak
acceleration such that the total energy of the shock pulse remains consistent. (Note: The peak
acceleration can be increased to minimize the pulse duration to accommodate specific test
equipment capability such that the total shock pulse energy remains consistent). The formulas
below are provided to calculate the appropriate peak acceleration and corresponding pulse width.
Peak Acceleration (gn) ≥
600 g𝑛 kg
𝑏𝑎𝑡𝑡𝑒𝑟𝑦 𝑚𝑎𝑠𝑠 (𝑘𝑔)
0.32
35.3
Pulse duration (s) = 𝑃𝑒𝑎𝑘 𝐴𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 𝑥√𝑏𝑎𝑡𝑡𝑒𝑟𝑦 𝑚𝑎𝑠𝑠
The minimum peak acceleration for any large battery shall be 10 gn.
Each large battery shall be subjected to three shocks in the positive direction followed by three
shocks in the negative direction of three mutually perpendicular mounting positions of the
battery for a total of 18 shocks.
Cells and batteries meet this requirement if there is no mass loss, no leakage, no venting, no
disassembly and no fire and if the open circuit voltage of each test cell or battery after testing is
not less than 90% of its voltage immediately prior to this procedure. The requirement related to
voltage is not applicable to test cells and batteries at fully discharged states.