I am using a little USB -> 3.7V board to charge my battery. It has a jack for a battery, and also through-holes to solder to. The through-holes are directly connected to the battery, so I'm using them to connect the battery to the NBv2. Bonus, I can run the saber with a dead or missing battery straight from USB. This has been great for testing things.

Anyway, here's the wiring-diagram without a kill switch.
WD.jpg
A kill switch would go on the negative (black) wire before it Ts off to the momentary switch. Correct?