Abstract: Disclosed is a multi-cell battery pack system that includes a plurality of cylindrical cells; a cradle with an interior surface that defines a channel extending through the length of the cradle and an exterior surface that mechanically positions each of the cells radially around and parallel to the channel and exchanges heat with the cells by extending around of the circumference of the cylindrical cell and substantially extending between the two opposing end surfaces of the cell; a heat conductor that resides at least partially within the channel and exchanges heat with the interior surface of the cradle; and a heat exchanger that exchanges heat with the heat conductor, wherein the cradle, the heat conductor, and the heat exchanger cooperate to exchange heat between the cells and the heat exchanger.