So I've been replacing a cell on my hybrid battery and had a stubborn nut. Like an idiot, I over-torqued it and broke the bolt. My question is, anybody know a way to ensure a proper connection here without replacing the cell? If not, do you think with the surrounding nuts there's enough contact to trust this with one broken bolt? I appreciate any advice you've got.
This depends entirely on what you're actually talking about. If you are talking about snapping off the threaded stud that fastens the busbar, then you need to replace the module. If you're talking about the mounting bolt that is under the module, fastening the module to the steel case, then no, it will have no effect on the integrity of the battery.
A strong hybrid pack will deliver 150 amps during a full throttle acceleration, from a dead stop. All modules/connections MUST be able to support this. Your broken stud has rendered that module as "toasted". PS: Purchase a proper torque wrench before working on your pack.
You also might want to completely clean or replace those bus bars. Any corrosion or high resistance will cause problems. Check the battery ecu connections for corrosion as well. If you are "just" replacing some modules (no charge/discharge cycling), then good luck.