Headway Series Threaded Connector Rod
These little threaded rods allow you to screw headway cells together in series without using a busbar. One side even has a little hex end if you wanted to tighten it before connecting the other battery. What we do is hand thread it halfway on one cell then line up the next cell and twist them together. If you can utilize this type of design you will save a lot of money on busbars and also cell to cell is the best connection you can have. We recover these rods out of the super beast Headway battery modules so they are made specifically for Headway cells.
You can make a 4s 12v Headway battery with 4 cells and 3 of these series connectors. An 8s battery you only need 7 of these, one in between each series connection. You can also add ring terminals to your BMS balance leads and slide that in between the cells for your balance lead connections.