I feel like BuM doesn't rely on the limited input current. I'm positive that there are other brands that do rely on it. I should know, but that project is on the list.

I feel like battery powering dyno lights should work in most cases, with the caveat that you are losing a diode drop in voltage. I think I have seen circuits that use a capacitor for voltage doubling and that wouldn't work with a battery. Been a while, they might not block all current.