battery presentation dc 9-29-14

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. [email protected]

1

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.

Problem Statement:

• 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.

Objectives:

2

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:

Introduction

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

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.

3

Transportation Mechanical Environments

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

Transient responses experienced on a Bedford 4x4 truck on a good quality road

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

4

REFERENCE Acceleration Pulse Duration Number of

Shocks Pulse Form gn milliseconds

UN38.3 T.4 50 11 18 Half sineSAE 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

>12≤100 kg 25 15 >100 kg 10 20

IEC61373 18 Class A & B

Body Mounted 3.1-5.1 30

Bogie Mounted 30.6 18 Axle Mounted 102 6

LITERATURE INFORMATION

5

Shock ScenarioAcceleration

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

ADDITIONAL DATA COLLECTED BY THE NAVAL RESEARCH CENTER

6

DROP TEST SET-UP

EXPERIMENTAL SET-UP 12/2013

7

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)

8

Computer Monitors (gn, T, V, Pulse, visual)

9

VARIABLES TO BE TESTED

Types of Surfaces Mass of Battery

Height of Battery being Dropped

10

0 200 400 600 800 10000

1000

2000

3000

4000

5000

6000

7000

8000

9000Power Spectrum of Filtered Acceleration Signal

Frequency (Hz)

Pow

er

0 10 20 30 40-10

0

10

20

30

40

50Filtered Acceleration Signal

Time (s)

Acc

eler

atio

n (g

)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.

Time (ms)

11

0 200 400 600 800 10000

1000

2000

3000

4000

5000

6000

7000

8000


Frequency (Hz)

Pow

er

0 10 20 30 40-20

0

20

40

60

80

100

120


Time (s)

Acc

eler

atio

n (g

)

0 200 400 600 800 10000

2000

4000

6000

8000


Frequency (Hz)

Pow

er

0 10 20 30 40-400

-200

0

200

400


Time (s)

Acc

eler

atio

n (g

)

0 500 1000 1500 20000

5000

10000


Frequency (Hz)

Pow

er

0 10 20 30 40-10

0

10

20

30

40


Time (s)

Acc

eler

atio

n (g

)

Various impact surfaces

Height: 11”Surface: 2” plywood + 2 rubber mattes + 1” foam

Height: 11”Surface: 2” plywood

Height: 11”Surface: ½” Steel

Time (ms)

Time (ms)

Time (ms)

12

0 10 20 30 40-400

-200

0

200

400

600

800


Time (s)

Acc

eler

atio

n (g

)

0 1000 2000 3000 4000 50000

0.5

1

1.5

2x 10

4Unfiltered Power Spectrum of Acceleration Signal

Frequency (Hz)

Pow

er

0 10 20 30 40-400

-200

0

200

400

600


Time (s)

Acc

eler

atio

n (g

)

0 500 1000 1500 20000

0.5

1

1.5

2x 10


Frequency (Hz)

Pow

er

0 200 400 600 800 10000

5000

10000


Frequency (Hz)

Pow

er

0 10 20 30 40-50

0

50

100

150

200


Time (s)

Acc

eler

atio

n (g

)

Various Heights




X 10-3

X 10-3

X 10-3

Time (ms)

Time (ms)

Time (ms)

13

SUMMARY OF DATA (16 kg weight battery) Drop Height (inches)

SURFACE TYPE gn

pulse duration

(ms) gn

pulse duration

(ms) gn

pulse duration

(ms) gn

pulse duration

(ms)

Foam 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 Foam = 2" plywood + 2 rubber mattes + 1" foam24 inches = 0.61 m Plywood = 2" plywood 36 inches = 0.91 m Concrete = 48 inches = 1.22 m Steel = 1/2" steel plate

11 24 36 48

14

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.

15

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

16

OBSERVATIONS FROM EXPERIMENTS● Type of Surface: Pulse duration remains about the same for the same type of drop surface even at different heights.

● Mass: As mass increases, gn decreases for a given surface and height.

gn is inversely related to square root of mass.

● 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.

17

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

18

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

Battery Wt (kg)

Drop Ht (cm)

No. of Drops Surface

<45.4 122 26

2" Plywood backed by concrete

45.4-90.8 76 8 "90.8-454 61 8 "

>454 46 5 Concrete

20

QUESTIONS?

battery presentation dc 9-29-14

Documents