I'm unsure of what battery chemistries can run on the P7's. Matter of fact, I tried doing a Google search for P7's from U.S. vendors and either got some really pricey amazon offerings or the MS900 from Geoman.

Got some of the Rayovac Hybrids for the oldest- so she wouldn't be getting into her mother's Energizers.

What I'll probably end up doing is just getting a cheap Rominsen that has 280 lumens (which is 2x more than what I already have). Then make the leap to more serious "bike specific" lighting systems.