A heat exchanger for thermal management of battery units made-up of a plurality of battery cells or containers housing one or more battery cells is disclosed. The heat exchanger has a main body portion formed by a pair of outer plates and an intermediate plate defining a primary heat transfer surface on either side of the heat exchanger for contacting a corresponding surface of at least one of the battery cells or containers. The intermediate plate together with the outer plates forming a plurality of alternating first and second fluid flow passages the flow direction through the first fluid flow passages being generally opposite to the flow direction through the second fluid flow passages. The first and second fluid flow passages are formed on opposite sides of the intermediate plate and are fluidly interconnected at corresponding ends creating a counter-flow arrangement through the main body portion of the heat exchanger.