TonyWilliams wrote:So, how do we know these are "B" cells, and more importantly, how do we even know they are the same 3100ma cells that Model S uses?
I'm not sure there is such a thing as a "B" cell. It is a "B" pack on the Model S. For all we know A,B,C and D packs all use the same cells. Some theorize that the B and newer packs have cell improvements, but other doubt that and just think is is some other limitation related to pack construction. Personally I think they may both be correct. I doubt there have been 4+ chemistry changes in the pack, so at least some of the changes are probably due to just improvements in pack construction. Some are potentially performance improvements, but I'd bet some are just improvements that shorten the time to construct a pack. Tesla is working hard to improve the production line, and the speed of these pack builds is one of the main components.
As far as knowing what is inside a Tesla Model S pack versus what is inside a Rav4EV pack, you'd have to open the packs remove some cells and test them. Or you could ask Tesla if they were willing to give an answer. I doubt they would tell you (not specifically you, but anyone), and not many folks willing to have the pack opened and then have individual cells removed for testing and comparison.