I set up an interesting thermal comparison. I made two 0.061" thick aluminum plates that are the same size as the cells, and two that were 2" longer and wider.
I placed the same size plates top and bottom of one cell. and the larger plates so the extra 2"of plate was off the bottom and one side of the other cell. the top and bottom plates form a heat sink area where I can blow air.
As expected, the cell with extra fins was only half as hot as the one with only the plates, it stayed under 85F. What I did not expect was that the cool cell dropped off noticeably quicker than the warm one. will reverse the heatsinks and do another run, to see if things change cells as final confirmation.
**** Results of moving the heat sink to the other cell was as expected, the cool side being changed also changed the cell that dropped out first almost exactly the mirror image of this trace. Temperature matters. Where is the sweet spot between longevity, temperature, capacity