Pipeline and Hazardous Material Administration

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• Pipeline and Hazardous Material Administration
• (PHMSA)
• Department of Transportation
• EXPERIMENTAL SHOCK TEST DATA ON
  LARGE LITHIUM BATTERIES
• Presented at second UN informal working group
  on large lithium batteries
• September in Washington, DC
• Steve Hwang, Ph.D.
  steve.hwang_at_dot.gov

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Problem Statement
The design type tests specified by the UN manual
of Tests and Criteria require large format
batteries to be subjected to a half-sine shock of
peak acceleration of 50 g and pulse duration of
11 ms. The force required to generate the test
conditions may not be indicative of transport or
reasonable abuse conditions for large format
batteries some of which may exceed 400 Kg.
Objectives

• Study the dynamic loads experienced by large
  format batteries during transportation and
  evaluate whether the current UN/DOT 38.3 T4 shock
  test accurately represents transportation
  environments
• If the study found the current test not to be
  valid, propose criteria and methods for
  conducting shock test on large format batteries.

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Introduction
Batteries during the four modes of transportation
(road, rail, air, and sea) experience a variety
of dynamic forces. In general, these forces can
be divided into two categories
The first group encompasses the forces that are
experienced due to vibration and repeated shocks
due to road surface imperfections. These forces
result in dynamic deflections of battery
components. Dynamic deflections and associated
velocities and accelerations may cause or
contribute to structural fatigue and mechanical
wear of battery components.
The second category covers relatively infrequent,
non-repetitive shocks encountered in handling.
The most severe mechanical aspects of handling
are usually associated with the shocks and
transients arising from rough handling, and
particularly from the materiel being dropped
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Transportation Mechanical Environments
Transient responses experienced on a Bedford 4x4
truck on a good quality road
Responses were measured on the vehicles load bed
over the rear axle
The amplitude of transients experienced by
restrained cargos is significantly lower than
that likely to occur as a result of any
mishandling i.e. being dropped
Propeller transport aircraft landing shock

• Transient excitations (shock) are only
  experienced during landing and peak in the case
  of fixed wing propeller aircraft.
• The amplitude of the transients can attain a two
  g experienced during air transportation will be
  less severe than that likely to occur as a result
  of any mishandling i.e. being dropped

The maximum reported acceleration for switching
operations is 15 g for traditional loose coupled
wagons. The amplitude of the transients
experienced during rail transportation will be
less severe than that likely to occur as a result
of any mishandling i.e. being dropped
In sea transportation the payload experiences
mainly quasi-static loading rather than dynamic
motions. The quasi-static inertia loadings are
usually of such low magnitude as not to cause any
concern
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LITERATURE INFORMATION
REFERENCE  Acceleration Pulse Duration Number of Shocks Pulse Form
  gn milliseconds    
UN38.3 T.4 50 11 18 Half sine
SAE J2464 25 15 18 Half sine
RTCA DO-160F Airborne Equipment 20 11 6 Saw tooth
USAF ASD-TR-76-30 December 1977 FAA 14CFR 25.561 9     Crash data
ISO/DIS 12405-1 50 10 6 6
Annex 8 to Regulation No. 100, 02 Series of amendments 17-28 80   Single step
UL2580 25 15 18  
UL 2271       Half sine
12 kg 50 11    
gt12100 kg 25 15    
gt100 kg 10 20    
IEC61373     18  
Class A B Body Mounted 3.1-5.1 30    
Bogie Mounted 30.6 18    
Axle Mounted 102 6    

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ADDITIONAL DATA COLLECTED BY THE NAVAL RESEARCH
CENTER
Shock Scenario Acceleration gn Pulse Duration milliseconds Number of Shocks Pulse Form
Typical wooden packages impacting a wood load platform during carriage over rough roads 40  Not provided Not Provided Not provided
Landing-fixed wing propeller aircraft 2  Not provided Not provided Not provided
Rail-Switching operations 15  Not provided Not provided Not provided
MIL-STD-810G, Method 516.6 Drop heights range from 18"-48" depending on weight. The number of drops ranges from 5 to 26 depending on weight. Not provided

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DROP TEST SET-UP
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EXPERIMENTAL SET-UP 12/2013
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Drop Test Set Up

• An accelerometer was placed on the base plate to
  measure the input acceleration.
• Two accelerometers were placed on the battery to
  measure the battery top plate response.
• Battery voltage and temperature were measured.
• The first set of drops were used to iteratively
  find the drop height and surface type that result
  in a 50 g, 11ms, half-sine input acceleration
• Next the battery underwent drops from 24, 36,
  and 48.
• Other impact surfaces were tested besides the
  surface required for 11ms pulse (2 wood plate,
  concrete and 1/2 steel plate)

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Computer Monitors (gn, T, V, Pulse, visual)
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VARIABLES TO BE TESTED
Types of Surfaces Mass of Battery Height of
Battery being Dropped
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50G 11ms Drop Test Impact Surface 2 plywood 2
rubber mats 1 foam

• Battery temperature and voltage remained constant
  during the test.
• No venting or leakage was observed.
• No mechanical deformation was observed.

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Various impact surfaces
Height 11 Surface 2 plywood 2 rubber mattes
1 foam
Height 11 Surface 2 plywood
Height 11 Surface ½ Steel
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Various Heights
Height 24 Surface 2 plywood
X 10-3
Height 36 Surface 2 plywood
X 10-3
Height 48 Surface 2 plywood
X 10-3
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Discussion of T4 Shock Test
 

• Pulse width of transients depends on material
  characteristics of the impact surface and the
  dropped object.
• The spectral content of the excitation energy has
  periodic peaks and notches in the frequency
  domain. All modes that coincide with the peaks
  of the frequency response function (FRF) will be
  preferentially excited, while the modes that
  coincide with the notches in the excitation FRF
  will not be excited.

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Summary/Discussion

• Testing Indicated that that the fixed
  acceleration and pulse duration parameters
  defined in the current T4 shock test could induce
  responses in test items that are not
  representative of abuse conditions during
  transportation.
• Our data suggest that drop testing is more
  representative of worst case transportation
  conditions.

Drop Test 50G 11ms Shock
Encompasses all the dynamic forces experienced during transportation Not universally representative of transportation environment for every battery design
Simpler test apparatus Economically impractical for large format batteries
Repeatability is an issue Repeatability makes it more attractive from a regulatory stand point
Further research is needed to define proper test parameters such packaging and drop height
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• OBSERVATIONS FROM EXPERIMENTS
• ? Type of Surface Pulse duration remains about
  the same for the same type of drop surface even
  at different heights.

? Type of Surface The harder the surface, the
higher the gn and the shorter the pulse duration.
? Height As the height increases, gn
increases for a given surface. gn is
directly proportional to the drop height.
? Mass As mass increases, gn decreases for a
given surface and height. gn is
inversely related to square root of mass.
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• Handling Scenario at 24 inch drop on 2 Plywood
  backed by concrete for a 16 kg battery with a
  0.95 ms pulse duration and 358 gn

Weight (Kg) 12 15 20 25 30 35 40 45 gt45
Height(cm) 81 65 49 39 33 28 24 22 22

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• Comparison to the US Military Standard
  (MIL-STD-810G, Method 516.6)

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QUESTIONS?