A lithium-ion battery module, comprising: - a terminal block assembly that defines a major terminal of the battery module and that is secured to a polymer housing of the battery module, the terminal block assembly comprising: - a terminal post having a post portion and a base portion that extends outward from a central axis of the post portion; - a bus bar physically coupled to the base portion of the terminal post without welding to form an electrical assembly, wherein the bus bar is electrically coupled to a first plurality of cell terminals of a plurality of lithium-ion battery cells disposed within a water-tight interior volume of the polymer housing, and wherein the bus bar includes a U-shaped trough near the terminal post, and a hairpin bend disposed adjacent to the trough, wherein the hairpin bend extends in a direction opposite the trough; and - a polymer portion having a substantially rectangular cross-section and overmolding at least the trough and the hairpin bend of the bus bar such that, when overmolded, the trough forms a drainage channel near the terminal post, and wherein the trough is disposed near an interface between the polymer portion and an exposed base of the bus bar surrounding the terminal post, wherein the exposed base of the bus bar is not overmolded by the polymer portion. - a terminal block assembly that defines a major terminal of the battery module and that is secured to a polymer housing of the battery module, the terminal block assembly comprising: - a terminal post having a post portion and a base portion that extends outward from a central axis of the post portion; - a bus bar physically coupled to the base portion of the terminal post without welding to form an electrical assembly, wherein the bus bar is electrically coupled to a first plurality of cell terminals of a plurality of lithium-ion battery cells disposed within a water-tight interior volume of the polymer housing, and wherein the bus bar includes a U-shaped trough near the terminal post, and a hairpin bend disposed adjacent to the trough, wherein the hairpin bend extends in a direction opposite the trough; and - a polymer portion having a substantially rectangular cross-section and overmolding at least the trough and the hairpin bend of the bus bar such that, when overmolded, the trough forms a drainage channel near the terminal post, and wherein the trough is disposed near an interface between the polymer portion and an exposed base of the bus bar surrounding the terminal post, wherein the exposed base of the bus bar is not overmolded by the polymer portion. - a terminal post having a post portion and a base portion that extends outward from a central axis of the post portion; - a bus bar physically coupled to the base portion of the terminal post without welding to form an electrical assembly, wherein the bus bar is electrically coupled to a first plurality of cell terminals of a plurality of lithium-ion battery cells disposed within a water-tight interior volume of the polymer housing, and wherein the bus bar includes a U-shaped trough near the terminal post, and a hairpin bend disposed adjacent to the trough, wherein the hairpin bend extends in a direction opposite the trough; and - a polymer portion having a substantially rectangular cross-section and overmolding at least the trough and the hairpin bend of the bus bar such that, when overmolded, the trough forms a drainage channel near the terminal post, and wherein the trough is disposed near an interface between the polymer portion and an exposed base of the bus bar surrounding the terminal post, wherein the exposed base of the bus bar is not overmolded by the polymer portion.