A battery assembly may include a cooling system assembly having first and second battery modules and a coolant manifold in fluid communication therewith. The first battery module may include a first coolant flow path and the second battery module may include a second coolant flow path. The coolant manifold may include first and second ports and a main body portion to provide expansion and contraction between the first and second ports. The first port may be in communication with the first flow path and the second port may be in communication with the second flow path.