The present disclosure relates generally to the field of batteries and battery modules, and more specifically, relates to a system and method for manufacturing terminal assemblies for lithium-ion battery modules. A disclosed battery module includes a terminal block assembly that is secured to a polymer housing of the battery module. The terminal block assembly includes a terminal post having a post portion and a base portion that extends outward from a central axis of the post portion. The terminal block assembly also includes a bus bar coupled to the base portion of the terminal post without welding, wherein the bus bar includes a trough disposed near the terminal post. The terminal block assembly further includes a polymer portion overmolding at least the trough of the bus bar to form a drainage channel near the terminal post.