A heat exchanger for battery thermal management applications is disclosed. The heat exchanger has at least one internal, two-pass flow passage, the at least one internal, two-pass flow passage having an inlet end and an outlet end and at least a first flow passage portion and at least a second flow passage portion interconnected by a generally U-shaped turn portion. An inlet manifold is in fluid communication with the inlet end of the internal flow passage for delivering an incoming fluid stream to the heat exchanger while an outlet manifold is in fluid communication with the outlet end of the internal flow passage for discharging an outgoing fluid stream from the heat exchanger. A bypass passage fluidly interconnects the incoming fluid stream and the outgoing fluid stream.