This is a small project I have done to connect my tiny whoop batteries to my B6AC charger. It connected batteries in a serial manner and then allow me to connect cells to the charger. Those extra pins also allow me to switch easily between 1-6 batteries.

While that's a clean solution, I am worried about those wires! They are not rated for conducting large amount of current (might get overheat)... might be wise and safer to use thicker wires...

Thanks. Yes. That's right. However, I checked several times them during charging and they were ok. I think the reason is that they use 0.2mah and so don't get hot.