The Phoenix heat and batteries - Leaf

Logical fallacy.
The statement was "...parks it outside in 140 degrees..." not your statement of "If you park it in the sun at work".
That may be the same for you, but not necessarily everyone.

While some will use this a an issue to ding all EVs, I suspect this doesn't affect most EVs nor the PiP due to different design choices.
Passive battery management doesn't work well in extreme temperatures.

 

is there a scientific way for nissan to diagnose battery degradation as caused by parking outside in 140 degree temperatures for prolonged periods?

 

I am sure there is.
My understanding is Nissan did a large amount of hot weather testing in Arizona.
I suspect they focused too much on air temperatures and lab results rather than asphalt parking lot temperatures.
They are gathering a half a dozen real world vehicles from people that have experienced capacity loss.
The problem may not be the parking of the car on 140 asphalt as much as charging the car in the evening and having it sit fully charged in a garage that doesn't cool below 90.
Or starting the charge before the batteries have had a chance to cool down.
I hope Nissan will release full details about what they discover.
I have seen reports of Arizona Leaf owners hat have had no problems as well. So at least some part of this is affected by user behavior.

 

The 90 degree number was just an educated guess, pure coincidence
As for the Model S, you really don't need to worry nearly as much as Leaf owners. Tesla uses an active battery management system which does a lot of the things Leaf owners are tring to do manually, automatically.
Plug the car in at anytime, the management system will cool or warm (which is what I worry about more) to make it safe to charge the batteries.
Standard charge setting is available and is the default setting for charging (80% vs 100% charge).

Basically, I have always thought an active battery system made much more sense than a passive one.

 

I very much wanted to read up on EV technology before buying one. And have been driving electric for a couple of years now. So a mix of ongoing research, and living the dream
When the news came out about the Az leafs, I started doing more digging.
News blurbs rarely give you the whole, or unbiased picture. They were awful with the Volt battery fires, awful with the Toyota unintended acceleration, and I suspect they will be just as bad with the Az Leaf battery issues.