Patent ID: 8361642

Claim:
A battery pack thermal management system, comprising: a battery pack enclosure configured to hold a plurality of batteries, wherein said battery pack enclosure is comprised of a high temperature material; and an enclosure failure port assembly integrated into a wall of said battery pack enclosure, wherein said enclosure failure port assembly remains closed during normal operation of said battery pack, and wherein said enclosure failure port assembly opens during a battery pack thermal runaway event and provides a flow path for exhausting hot gas from within said battery pack enclosure, wherein said enclosure failure port assembly directs said flow path at an angle away from a normal of said wall of said battery pack enclosure, and wherein said enclosure failure port assembly further comprises: a substantially circular region of said wall, wherein a transition region is interposed between said substantially circular region and a surrounding portion of said wall, wherein said transition region completely encircles said substantially circular region of said wall, wherein a first portion of said transition region encircling a first portion of said substantially circular region is scored by scoring of a first depth and wherein a second portion of said transition region encircling a second portion of said substantially circular region is scored by scoring of a second depth, wherein said second depth is greater than said first depth, wherein said second portion of said transition region fails before said first portion of said transition region during said battery pack thermal runaway event and allows hot gas from within said battery pack enclosure to exhaust through said substantially circular region at an angle away from said normal of said wall of said battery pack enclosure.