Traction battery pack immersion thermal management system with multiple outlet ports

A battery pack immersion thermal management system, comprising:

• a coolant delivery system that communicates a coolant from a coolant supply to a battery case that houses a cell stack, the coolant delivery system including at least one inlet port to the battery case;
• a battery pack enclosure assembly housing the battery case that houses the cell stack;
• and
• a coolant return system that communicates the coolant from the battery case back to the coolant supply, the coolant return system including a plurality of outlet ports and a return manifold, the plurality of outlet ports each separately fluidly connecting the battery case to the return manifold, the return manifold configured such that coolant received from each of the plurality of outlet ports is mixed within the return manifold prior to reaching the coolant supply, wherein the plurality of outlet ports are disposed entirely within the battery pack enclosure assembly,
• wherein the plurality of outlet ports includes a first outlet port extending from the battery case to the return manifold and a second outlet port extending from the battery case to the return manifold separately from the first outlet port,
• wherein the first outlet port is vertically above the second outlet port.