jdcbomb wrote:What actual temp (F) is considered high and "detrimental" for the life of the 40 kWh battery. Greater than 90? Greater than 120? Assuming a 12 hr period here as it appears the battery doesn't drastically dissipate the heat once it is gained.
"Detrimental" isn't really how it works.
Li ion batteries have side reactions that remove active Lithium and otherwise degrade the anodes and cathodes.
These reactions happen in any Li ion battery at any operational temperature. Like most chemical reactions, these reactions seem to follow an Arrhenius relationship, going faster at higher temperatures. A temperature higher by 10C or a bit less would double the rate of capacity loss.
So if your "normal" battery temperature is 25C, a day trip that raises that to 35C will roughly remove an extra day of battery life. A day trip that raises battery temperature to 45 C would remove roughly three extra days of battery life.
This is a crude back of envelope type calculation. A better calculation could be done by considering the warmup time and the cooling time, and using the roughly 8C best fit for the Arrhenius relationship. The results wouldn't be much different.
If you do a trip that adds 10C once a year, I doubt if you can observe the faster rate of capacity decline, even with multiple cars driven exactly the same. If you do a trip that adds 30C three times a week, different story.