Electric arcs or internal shorts that can potentially occur inside Lithium-based batteries are extremely hot and very energetic – inner cores of arc plasmas can reach peak temperatures as high as 35,000 degrees F or ~19,427 C. Such arcs can be triggered by massive separator failures and are very damaging --- physical effects can extend well beyond the battery cells in which they begin and may be instrumental in causing some worst-case catastrophic thermal runaway events. Some of these energetic collateral effects of internal shorts are called “arc flashes” and “arc blasts”; the following describes some of the potential consequences of an arc blast in a failing battery system: Quoted from the following source = http://www.arcadvisor.com/faq/arcblast.html Arc blast pressure: Electric arcs produce some of the highest temperatures known to occur on earth - up to 35000 degrees Fahrenheit or 19500 degrees Celsius. This temperature is four times higher than the temperature on the surface of the Sun. The intense heat from an arc causes sudden expansion of air resulting in a blast. Copper expands during an arc flash event at a factor of 67,000 times within a few milliseconds. Because the chest and face area for most workers make up nearly half a square meter of surface area, a worker could easily be blown off his feet or somersaulted during an intense arc flash explosion. As an example, a 50kA arc would provide enough pressure to propel a person standing 2 feet away from the arc source and weighing 75kg (170 lbs) with acceleration of approximately 100 meters (330 feet) per second. The arc flash blast energy or pressure is not currently addressed in IEEE 1584 or NFPA 70E. Ralph Lee's IEEE paper Pressures Developed by Arcs addresses arc blast phenomenon and provides the formula for calculating initial impulse force: P = 11.58 x Iarc / D0.9 Where: P is pressure in lbs/ft2 ; Iarc is arcing current in kA; and D is distance from the arc plasma in feet. While arc blasts in batteries are likely to be extremely rare events, their untoward consequences would assuredly be violently catastrophic.

1. Lattice Energy LLC
Electric arc discharges inside batteries are hot and energetic
Lattice Energy LLC, copyright 2013 All rights reserved , May 15, 2013 1
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“NTSB reports indicate very high temperatures”
Technical Discussion (51 MS-PowerPoint slides)
Lewis Larsen, Lattice Energy LLC, May 7, 2013
http://www.slideshare.net/lewisglarsen/lattice-
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