Abstract: A battery pack assembly having a casing enclosing stacks of cells. The casing defines a plurality of air intake chambers for receiving a flow of air and a plurality of slots diametrically opposite of the air intake chambers for dispensing the flow of air, and the air flows circumferentially through a gap around the cell walls to cool the cells. A plurality of circumferentially and radially spaced flow interrupters are disposed on at lest one of the cell wall and the casing for disrupting the flow of air to increase the heat transfer coefficient of that air.

Abstract: A battery pack assembly including a plurality of cells surrounded by a spacer for creating a radial space between the cell and cylindrical sections defining a casing. At least two of the cylindrical sections are conical or in different radial positions to define differing volumes between the respective two cells. Each of the cylindrical sections may be eccentrically offset from the respective cell to define a greater radial space adjacent the air inlet chamber and a lesser radial space adjacent the respective exit to increase the velocity of the discharging air adjacent the respective exit. Each of the cylindrical sections may have a casing undulating surface extending circumferentially and/or each of the walls of the cells may have a similar cell undulating surface to increase the cooling capacity of the cooling air.

Abstract: A battery pack assembly comprising a plurality of battery packs each including a plurality of cells and a plurality of blocking pieces. Each battery pack defines an air path therethrough and each of the air paths includes an air inlet chamber extending the length of the respective battery pack for supplying air. Each air path is defined on one side by the cylindrical walls of the cells. Each of the cells has an exposed portion being the portion of the respective cell adjacent and exposed to said air inlet chamber. The blocking pieces are disposed in the air inlet chamber. Each blocking piece extends longitudinally along the length of one of the cells and each blocking piece is associated with one of the cells. Each of the blocking pieces reduces the size of the exposed portion of the respective cell to meter the flow of air around the respective cell.