Method for cooling a lithium-ion battery pack

A battery module comprising:

• a module housing and a cooling system configured to receive heat from the module housing via conduction;
• and
• wherein the cooling system comprises a cooling surface being generally rectangular in shape and formed from a conductive material, the cooling surface having a cooling route created within a cold plate, and wherein the cooling system comprises two headers disposed at least partially external to the cold plate, at least partially internal to the cold plate, and parallel with one another;
• and
• cross flow branches of the cooling route, wherein the cross flow branches are in fluid communication with the two headers, wherein the cross flow branches extend between and perpendicular to the two headers, wherein each cross flow branch comprises an elliptical cross-sectional shape having a major diameter and a minor diameter smaller than the major diameter, and wherein each cross flow branch comprises an approximately 90° twist proximate to each header such that the major diameter of the elliptical cross-sectional shape of each cross flow branch is substantially parallel with longitudinal axes of the two headers between the approximately 90° twists and substantially perpendicular with the longitudinal axes of the two headers outside of the approximately 90° twists.