Hot and cold cells compared.
hot and cold cells compared
I charged both cells, then put one in the sun, and one in the freezer, and then once the temperatures stabilized, as quickly as I could, placed them in the test fixture and ran a medium 50A discharge to see what happened. The cold cell had a much bigger voltage drop that got better as the cell self heated, and the hot cell actually dropped in temperature before turning around and rising towards the end.
Looks like the cells like between 90-110F as their best performance zone.
Ran another run where I let the cells drop right out, and we see evidence that the self heating gets worse as the cells start dropping that last 2V.