Focus Slide

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Focus Slide
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Why did they recall my laptop battery?

• ASSE HOA Chapter
• Monday, April 14, 2008

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• Agenda
• Electrical Basics
• Battery Basics
• Benefits of Lithium Ion Batteries
• Hazards of Lithium Ion Batteries
• Conclusion

Concise Overview of Li-ion Technology
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What is the voltage of this battery?
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7.2 Volts
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6 Ways to Generate Electricity

• Magnets (electromagnetics)
• Friction / static (triboelectrics)
• Light (photovoltaics)
• Pressure (piezoelectrics)
• Heat (thermoelectrics)
• Chemical (batteries / fuel cells)

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Battery Limited to Chemicals
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Why Use Lithium in a Battery?

• Atomic 3
• Soft alkali metal
• Lightest metal and least dense solid element
• 33rd most abundant element
• Not as hazardous (lead / mercury / acids)
• Unstable
• Reacts and corrodes

Pros and Cons
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Uses

• More and more consumer electronic devices move to
  using lithium-ion (Li-on) batteries
• Laptops
• Cell phones
• Digital cameras
• Flashlights
• I-pods
• Calculators
• High end power tools
• Electric vehicles
• Etc.

Widespread Use
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Benefits

• Lithium-ion batteries are relatively new and
  offer these advantages over other rechargeables
  (like nickel-cadmium (NiCd) and
  nickel-metal-hydride (NiMH))
•         o  holds a longer charge
• (low self-discharge rates)
•         o  withstands more recharge cycles (300
  500)
•         o  lower cost-per-energy ratios
•       o  higher energy densities
• (energy-to-weight ratios energy-to-size
  ratios)
•         o  higher voltages per cell (usually
  3.7v versus 1.5v)
•         o  has little or no "memory effect"
• (lazy battery effect)

Great Advantages
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Hazards

• Failures occur either because the battery pack (a
  connected unit) is faulty or the individual cell
  is faulty (contaminated)
• When a fault occurs, the following may happen
•        
• o  the equipment may not operate  (battery
  "deep discharge")  BEST
•      o  the battery may overheat / melt
  (thermal runaway 200oC)
•        o  the battery may rupture / explode  
  WORST  

Wide Range of Possible Outcomes
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Failure Modes (Contamination)

• An ultrathin separator membrane provides
  electrical insulation between the battery's
  cathode and anode
• o a metal particle pierces the separator
• o multiple particles accumulate (plate) onto
  an electrode
• o multiple particles form dendrites that
  grow through microscopic pores in the separator
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All Bad Situations
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Reasons

• Explosions occur when contamination creates a
  chain thermal reaction -- reaction occurs in a
  fraction of a second  
• (a massive, instantaneous discharge with
  energies of explosive force)

Event Could Be Catastrophic
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Reasons

• To explode, the battery is either
• unvented or "dumb"  
• Newer Li-on batteries are designed with
• pressure relief vents and/or are "smart" --
  meaning they have an internal voltage monitoring
  circuit to shut the battery down if a problem
  exists

Safety Features Evolving Over Time
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Examples
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Examples
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Examples
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9v Lab Tests
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Precautions

• If you have and use lithium-ion batteries, here
  are some things you can do
•         o  do not keep them for prolonged periods
  in hot or cold environments
•         o  minimize storage in flammable
  containers
• (purses, drawers, pockets, etc.)
•         o  keep them away from flammables when
  charging
• (don't lay on carpeting, etc.)
•         o  keep them away from your body unless
  essential
• (like keep device in a holder versus directly
  in a pocket)  

Common-Sense Approach
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• QUESTIONS / COMMENTS
• Who ?
• What ??
• Where ???
• When ????
• Why ?????
• How ??????

Use a "Common Sense" Approach