At the Battery Safety 2012, on December 6-7 in Las Vegas, Nevada, Mr. Erik Spek, Chief Engineer at TÜV SÜD Canada presented on "An Approach to Robust, No Surprises Design Verification Testing."
Test Plan Development using Physics of Failure: The DfR Solutions Approach
An Approach to Robust, No Surprises Design Verification Testing [Presentation Slides]
1. Battery Safety 2012
A New Approach to
Robust, No Surprises Design Verification Testing
Erik J. Spek
Chief Engineer
TϋV SϋD Canada
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 1
2. Battery Safety 2012
The end user of battery driven cars expect the
same if not better than conventional cars.
Is this possible?
Do the normal engineering tools work?
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 2
3. Battery Safety 2012
Background Note:
The material for this presentation comes from
experience with many programs to develop and
launch automotive products both in the
traditional automotive products and battery
operated vehicles including 12 volt safety
components and the Ford/ABB Ecostar
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 3
4. Battery Safety 2012
Discussion Areas:
1.Background
2.The normal DVP (Design Verification Plan)
3.The differences between normal cars and
electrically driven cars
4.How do the risks of battery systems influence
the DVP
5.Some ways to address the differences and
examples
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5. Confidence ???
The acid test of
how well a product
meets customer
expectations.
“Probe of GM's Volt Fires May Be Lengthy”
What gives us
“Nissan Electric Cars May Lose Range In Hot confidence in the
Climates” product?
“Tesla Motors’ Devastating Design Problem”
“Consumer Reports review details flaws in
Fisker Karma sports car”
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 5
6. The Attention You Don’t Want
If the product fails,
as the design
engineer you will
receive plenty of
attention
$$$
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 6
7. Expectations
• The vehicles we buy, drive and
maintain today are considered to be:
• predictable,
• reliable,
• robust against abuse
• and afford the occupants a
measure of survivability in
accidents.
• Automotive product development
process:
• proven method to ensure end
product meets customer wants and
needs.
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 7
8. Verification of Expectations
• Design Verification Plan (DVP) with a
variety of tests:
• Shake and drop
• Hot and cold
• Altitude
• Water showers and immersion
• Corrosion
• Fire exposure
• Impacts
• Humidity
• Controls
• 12 volt source
• etc
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 8
9. Guaranteed Verification ???
• DVP uses the best available information on
abuses that can be imposed.
• Not a guarantee of no risk
• Unforeseen abuse conditions may occur in 12v
components leading to loss of function
• Aged components
• Humidity and dust
• Abnormal uses
• Salty air
• Example: major recall on Chrysler minivan
sliding door cable abrasion & short circuit
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10. Consequences of Failed DVP
• DVP may take multiple passes-usually do!
• Methods and equipment are well established
• Costs are known and managed
• Timelines are weeks to months after parts made
• Product level is usually ‘cut and weld’
• Program managers are trained to ‘make it
happen’ ON TIME and ON BUDGET through:
• Extraordinary measures as needed
• War room approach
• More budget if needed
• VEHICLE LAUNCHES MUST HAPPEN ON TIME
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 10
11. Are Electric Vehicle Batteries Different?
• High voltage – hundreds of volts
• Dangerous power levels
• High level of stored energy – for
extended power delivery
• Common implied expectation is
‘batteries not as hazardous as gasoline’
• Even 12 volt batteries can burn
• An invitation to product liability lawyers
• Noxious fumes
• Electric shock
• Survivable vs unsurvivable accidents
• Product liability
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12. How Does This Affect The DVP?
• 4 levels of product involved:
• individual cells,
• 10s of cells in modules,
• 10s of modules in a pack,
• pack in a vehicle
• Each level contributes to overall robustness verified by DVP tests
• The final product (pack) is the last line of defense against abuse.
• Pack subjected to variety of tests:
• Mechanical
• Electrical
• Thermal
• Each level has risks NOT NORMALLY FOUND IN USUAL
AUTOMOTIVE PARTS
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13. DVP Surprises
• The aim of the DVP is:
• Successful outcome of tests
• No damage or injury to people, equipment and facility
• NO SURPRISES
• DVP is hard enough and costly without surprises
• What surprises can occur:
• Accidents in testing
• Known defects in product heading into testing compromising
outcome
• Incorrect design level of component
• Unpredictable outcome
• SHOW STOPPERS …. Slows or stops the program
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 13
14. Risk of getting it wrong
Everything is great until an electric car is in an accident or fire
……………… then:
Product Liability Lawyers circling looking for:
• Incomplete documentation
• Holes in the DVP test plan
• Stranded tests – exposed risks
• Evidence of haphazard approach
• Unnecessary and or misleading data
• Accidents during testing
• Uncontrolled approach
• Lack of engineering discipline
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15. The Unavoidable
• Batteries including cells and modules are always on – inside
• Laws of physics and chemistry are always present
• Mechanical parts will break
• Liquids will leak
• Current carrying parts will overheat
• Plastic parts will become hot and soften
• Tests will cause failures
• Incorrect parts will be made and used
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16. Know the Risks
• Accepted risks for any 3rd party test house or
inside test lab
• Electric shock:
• Current path to touchable surfaces
• Can happen at any time during testing or
use
• Hundreds of volts (safe handling level is <
60Vdc)
• Dangerous gases and fumes (HF, soot, etc
• Fire
• Explosion
• Combinations of different tests introduce
compound hazards
• Shake and bake and cycle
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 16
17. Exploratory vs Confirmatory Testing
• DVP is not an R&D exercise or taking unnecessary risks
• DVP should report confirmation of a successful verification test
• If the outcome of the test is in doubt or has not been tried:
• Do the R&D work first as EXPLORATORY
• Stage the work:
• Simplest level first –controlled and unpowered
• Apply power from a controlled source
• Repeat with battery cells installed
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18. Survivable vs Unsurvivable Accidents
• Abuse tests may not show latent defects unless careful post test
analyses are conducted
• Semi-broken or fatigued bus high voltage components
• Effect of a lifetime of dust, humidity leading to isolation
degradation in ohmic value
• Increased hazard from aged cells
• Unsurvivable accident: clear catastrophic result
• Survivable accident: occupants pinned waiting for extraction only to
be hurt by a battery hazard
• Subject to possible product liability action
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 18
19. Example: Water Immersion
• Some vessels can tolerate a bit of salty water
on board
• Keeping the ship afloat can be achieved by
bailing and bilge pumps
• Ship electrical bus systems can tolerate the
presence of conductive water
• BATTERIES ARE DIFFERENT-NO
WATER ALLOWED!!!!!
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20. Example: Water Immersion
• Test: immerse pack in 5% salt water solution or
salt fog – some call fro hot pack into ice cold water
• Objective: determine consequence if water leaks
into pack
• Consequence: conductive water in high voltage
pack:
• Uncontrolled dissociation
• Cl2 and H2 – both dangerous
• Pack leaks= high risk & SURPRISE
• Solution: verify pack leak worthiness
• Staged approach:
• 1-EXPLORATORY: No cells
• 2-EXPLORATORY: Cycler powering high
voltage bus
• 3-CONFIRMATORY: complete pack test
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21. Example: Vibration & Shock
• Test: vibrate packs and shock to known profiles
• Objective: primarily verify no parts become loose, fatigued or broken
• Consequence on failure:
• High voltage bus compromised immediately or later
• Pack leaks= high risk & SURPRISE
• Solution: verify pack hardware structural integrity
• Staged approach:
• 1-EXPLORATORY: dummy cells
• 2-EXPLORATORY: cycler powering high voltage bus
• 3-CONFIRMATORY: complete pack test
TÜV SÜD 13/12/12 Battery Safety 2012 Slide 21
22. Example: Fire Resistance
• Plug In Hybrid Electric Vehicles (PHEV) carry gasoline on board
• Substantial batteries also on board
• A fuel fire is a possible event
• Test: subject pack to fuel fire
• Objective: verify response to external fire
• Consequence of failure:
• Aggravated risk of fire or explosion
• Solution: verify pack fire resistance
• Staged approach:
• 1-EXPLORATORY: dummy cells
• 2-EXPLORATORY: pack with active module
• 3-CONFIRMATORY: complete pack test
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23. Appropriate Facilities
Be Able to Contain Reactions up to Explosions
(EUCAR 7)
TÜV SÜD 13/12/12 Slide 23
24. Closing
DVPs for Battery Operating Cars:
1.Show only confirmation of tests for records
2.Keep exploratory tests as pre-DVP
3.Ensure that the tests in the DVP encompass all
reasonable abuse that could be encountered
4.Use a staged approach in R&D stage to build
success in hazardous tests
TÜV SÜD 13/12/12 Slide 24