A thermally conductive base member for battery packs (20, 22, 24, 26), comprising: a first metal base member having a first bottom plate, first and second female coupling portions (130, 132), and first and second rib portions (134, 136, 138, 140, 142); the first female coupling portion being coupled to a first end of the first bottom plate; the second female coupling portion being coupled to a second end of the first bottom plate; the first and second rib portions (134, 136, 138, 140, 142) of the first metal base member being coupled to and extending from a top surface of the first bottom plate and being spaced apart from one another, the first and second rib portions (134, 136, 138, 140, 142) of the first metal base member being disposed between the first and second female coupling portions (130, 132); a second metal base member having a second bottom plate, a first male coupling portion, and first and second rib portions (244, 246); the first male coupling portion being coupled to the second bottom plate proximate to a first end of the second bottom plate; the first and second rib portions (244, 246) of the second metal base member being coupled to and extending from a top surface of the second bottom plate and being spaced apart from one another; the first male coupling portion of the second metal base member being disposed in and coupled to the first female coupling portion of the first metal base member; a top plate being disposed on and coupled to a top surface of the first female coupling portion, a top surface of the second female coupling portion, and the first and second rib portions (134, 136, 138, 140, 142) of the first metal base member such that a first flow channel (406, 408, 410, 412, 414, 416) is defined between the first and second rib portions (134, 136, 138, 140, 142) of the first metal base member and the top plate; the top plate being further disposed on and coupled to the first and second rib portions (244, 246) of the second metal base member such that a second flow channel (418, 420, 422) is defined between the first and second rib portions (244, 246) of the second metal base member and the top plate; a first inlet port member being coupled to a top surface of the top plate that fluidly communicates with the first and second flow channels (412, 414, 416, 418, 420, 422); and a first outlet port member being coupled to the top surface of the top plate that fluidly communicates with the first and second flow channels (412, 414, 416, 418, 420, 422). a first metal base member having a first bottom plate, first and second female coupling portions (130, 132), and first and second rib portions (134, 136, 138, 140, 142); the first female coupling portion being coupled to a first end of the first bottom plate; the second female coupling portion being coupled to a second end of the first bottom plate; the first and second rib portions (134, 136, 138, 140, 142) of the first metal base member being coupled to and extending from a top surface of the first bottom plate and being spaced apart from one another, the first and second rib portions (134, 136, 138, 140, 142) of the first metal base member being disposed between the first and second female coupling portions (130, 132); a second metal base member having a second bottom plate, a first male coupling portion, and first and second rib portions (244, 246); the first male coupling portion being coupled to the second bottom plate proximate to a first end of the second bottom plate; the first and second rib portions (244, 246) of the second metal base member being coupled to and extending from a top surface of the second bottom plate and being spaced apart from one another; the first male coupling portion of the second metal base member being disposed in and coupled to the first female coupling portion of the first metal base member; a top plate being disposed on and coupled to a top surface of the first female coupling portion, a top surface of the second female coupling portion, and the first and second rib portions (134, 136, 138, 140, 142) of the first metal base member such that a first flow channel (406, 408, 410, 412, 414, 416) is defined between the first and second rib portions (134, 136, 138, 140, 142) of the first metal base member and the top plate; the top plate being further disposed on and coupled to the first and second rib portions (244, 246) of the second metal base member such that a second flow channel (418, 420, 422) is defined between the first and second rib portions (244, 246) of the second metal base member and the top plate; a first inlet port member being coupled to a top surface of the top plate that fluidly communicates with the first and second flow channels (412, 414, 416, 418, 420, 422); and a first outlet port member being coupled to the top surface of the top plate that fluidly communicates with the first and second flow channels (412, 414, 416, 418, 420, 422).