We asked Darryll Harrison, VW US's manager of brand public relations west, for more information, and he told AutoblogGreen that VW engineers discovered through a lot of testing of the Golf Mk6 EV prototypes, that battery performance was not impacted by temperatures when using the right battery chemistry. That chemistry, it turns out, is lithium nickel manganese cobalt oxide (NMC) in cells from Panasonic. These cells had "the lowest self-warming tendency and the lowest memory effect of all cells tested," Harrison said. He added that VW engineers tested the NMC cells in places like Death Valley and Arizona and found they didn't warm very quickly either through operation, charging (including during fast charging) or through high ambient temps. "The need for a cooling system wasn't there," Harrison said. Since the cells work so well, all the e-Golf needs to keep the battery pack at the right operating temperature is an intelligent thermal control (which regulates the amount of energy expended form each of the cells to keep the heat down) and the ability to dissipate what heat is created into the chassis and away from the pack.
http://green.autoblog.com/2014/03/31/vw-e-golf-will-not-have-active-cooling-system-lithium-battery/
http://green.autoblog.com/2014/03/31/vw-e-golf-will-not-have-active-cooling-system-lithium-battery/