A battery cell stack connector assembly includes a plurality of busbar modules. Each of the busbar modules has a module frame with a first side with a first connector and a second side with a second connector. Each module frame defines a module axis that extends from the first side to the second side. Each of the busbar modules also includes a busbar attached to the module frame. The plurality of busbar modules are connected to form a connector frame that defines a connector axis that extends from a first assembly side to a second assembly side. The module axes of the plurality of busbar modules are aligned with the connector axis. Also, the first connectors and second connectors are adapted so that each of the plurality of module frames is mated with and attached to respective adjacent module frames.