Traction battery pack assembling method

A battery pack assembly method, comprising:

• holding a cell stack with a compression machine, the cell stack including a plurality of battery cells disposed along a cell stack axis, the compression machine engaging a first load plate at a first axial end of the cell stack and a second load plate at an opposite, second axial end of the cell stack during the holding;
• aligning the cell stack relative to an enclosure structure while the compression machine holds the cell stack;
• inserting the cell stack into a cell-receiving opening of the enclosure structure;
• and
• disengaging the compression machine from the first load plate and the second load plate, the enclosure structure maintaining compression on the cell stack after disengaging the compression machine,
• wherein the compressing machine engages the first load plate through at least one first prong received within a cell stack slot of the first load plate, and engages the second load plate through at least one second prong received within a cell stack slot of the second load plate,
• wherein the enclosure structure includes at least one first clearance groove and at least one second clearance groove, the at least one first clearance groove receiving the at least one first prong along the cell stack axis during the disengaging, the at least one second clearance groove receiving the at least one second prong along the cell stack axis during the disengaging.