1
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@dot.gov
2
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.
3
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
4
Transportation Mechanical Environments
Transient responses experienced on a
Bedford 4x4 truck on a good quality road
Responses were measured on the vehicle’s 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
Number of
Shocks
Pulse Form
REFERENCE
Acceleration
gn
Pulse Duration
milliseconds
UN38.3 T.4
SAE J2464
50
25
11
15
18
18
Half sine
Half sine
RTCA DO-160F Airborne
Equipment
20
11
6
Saw tooth
USAF ASD-TR-76-30 December
1977 FAA 14CFR 25.561
9
ISO/DIS 12405-1
50
10
17-28
25
80
15
Crash data
Annex 8 to Regulation No. 100,
02 Series of amendments
UL2580
UL 2271
≤ 12 kg
>12≤100 kg
>100 kg
IEC61373
Class A & B
Body Mounted
3.1-5.1
30
Bogie Mounted
Axle Mounted
30.6
102
18
6
6
6
Single step
18
Half sine
50
25
10
11
15
20
18
6
ADDITIONAL DATA COLLECTED BY THE NAVAL RESEARCH CENTER
Shock Scenario
Typical wooden
packages impacting a
wood load platform
during carriage over
rough roads
Landing-fixed wing
propeller aircraft
Rail-Switching
operations
MIL-STD-810G,
Method 516.6
Acceleration Pulse Duration
gn
milliseconds
Number of
Shocks
Pulse Form
40
Not provided
Not Provided
Not provided
2
Not provided
Not provided
Not provided
15
Not provided
Not provided
Not provided
Not provided
Drop heights
range from 18"48" depending
on weight.
The number of
drops ranges
from 5 to 26
depending on
weight.
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EXPERIMENTAL SET-UP 12/2013
DROP TEST SET-UP
8
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
11
50G 11ms Drop Test
Impact Surface: 2” plywood + 2 rubber mats + 1” foam
Filtered Acceleration Signal
Power Spectrum of Filtered Acceleration Signal
9000
8000
40
7000
30
Power
Acceleration (g)
50
20
10
6000
5000
4000
3000
2000
0
1000
-10
0
10
20
30
0
0
40
Time
Time(ms)
(s)
200
400
600
800
1000
Frequency (Hz)
•
•
•
Battery temperature and voltage remained constant
during the test.
No venting or leakage was observed.
No mechanical deformation was observed.
12
Various impact surfaces
Filtered Acceleration Signal
Power Spectrum of Filtered Acceleration Signal
9000
8000
Height: 11”
Surface: 2” plywood
+ 2 rubber mattes +
1” foam
40
7000
30
Power
Acceleration (g)
50
20
10
6000
5000
4000
3000
2000
0
1000
-10
0
10
20
30
0
0
40
Time
(ms)
Time
(s)
Filtered Acceleration Signal
600
800
1000
Power Spectrum of Filtered Acceleration Signal
10000
120
8000
100
80
Power
Acceleration (g)
400
Frequency (Hz)
140
60
40
20
6000
Height: 11”
Surface: 2” plywood
4000
2000
0
-20
0
10
20
30
0
0
40
Time (ms)
(s)
200
400
600
800
1000
Frequency (Hz)
Filtered Acceleration Signal
Power Spectrum of Filtered Acceleration Signal
600
15000
400
Power
Acceleration (g)
200
200
0
10000
Height: 11”
Surface: ½” Steel
5000
-200
-400
0
10
20
Time (ms)
(s)
30
40
0
0
500
1000
1500
Frequency (Hz)
2000
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Various Heights
Filtered Acceleration Signal
Power Spectrum of Filtered Acceleration Signal
15000
200
150
Power
Acceleration (g)
250
100
50
Height: 24”
Surface: 2” plywood
10000
5000
0
-50
0
X 10-3
10
20
30
0
0
40
200
Time
Time(ms)
(s)
Filtered Acceleration Signal
2
600
800
1000
4
Spectrum of Filtered Acceleration Signal
xPower
10
Height: 36”
Surface: 2” plywood
600
1.5
400
Power
Acceleration (g)
800
200
0
1
0.5
-200
-400
0
X 10-3
10
20
30
0
0
40
500
1000
1500
2000
Frequency (Hz)
Time
(ms)
Time
(s)
Filtered Acceleration Signal
1000
2
4
Unfiltered
Power Spectrum of Acceleration Signal
x 10
Height: 48”
Surface: 2” plywood
800
1.5
600
Power
Acceleration (g)
400
Frequency (Hz)
400
200
0
1
0.5
-200
-400
0
X 10-3
10
20
Time
Time(ms)
(s)
30
40
0
0
1000
2000
3000
4000
Frequency (Hz)
5000
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SUMMARY OF DATA (16 kg weight battery)
11
Drop Height (inches)
24
pulse
duration
(ms)
gn
gn
36
48
SURFACE
TYPE
Foam
gn
pulse
duration
(ms)
50
11
77
11
93
11
127
10
Plywood
149
0.6
358
0.95
789
0.53
993
0.55
Concrete
548
0.5
1335
0.35
Steel
666
0.16
11 inches = 0.28 m
24 inches = 0.61 m
36 inches = 0.91 m
48 inches = 1.22 m
pulse
duration
(ms)
gn
pulse
duration
(ms)
Foam = 2" plywood + 2 rubber mattes + 1" foam
Plywood = 2" plywood
Concrete =
Steel = 1/2" steel plate
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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.
18
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
>45
Height
(cm)
81
65
49
39
33
28
24
22
22
19
20
Comparison to the US Military Standard (MIL-STD-810G, Method 516.6)
Battery Wt
(kg)
Drop Ht
(cm)
No. of
Drops
<45.4
45.4-90.8
90.8-454
>454
122
76
61
46
26
8
8
5
Surface
2" Plywood
backed by
concrete
"
"
Concrete
QUESTIONS?