Wow..I had no idea that leaving a lithium-ion battery in a hot car for a few hours could reduce its output permanently by 50%. Yikes.
That would explain the SLIDS (Sudden Lithium-Ion Death Syndrome) that a couple of my laptop batteries experienced a couple of years ago. Laptop left in flaming hot car multiple times, neglected because it was obsolete. After second battery I decided to retire it to a desk job. Amazing that the multiple 140degree heat conditions didn't fry anything else on it.
One problem with getting trustworthy data on Lithium-Ion batteries is that it's a moving target. No one knows how the latest technology is going to handle every conceivable condition, as it takes a year to accurately measure a year. It appears the technology is changing every six months. Here is a good link for charts and info:
http://www.batteryuniversity.com/parttwo-34.htm
Hopefully pretty soon we'll all have ability to power our very own Ironman suits.