Single battery would mean a change to a different regulator. Buzz has a really, really, good regulator now, good control, good run time (efficient), higher max power than the boost-only single-battery units out there (Pretty sure the Provari maxes at 12.5W output, while notcigs units go to 15). It has thousands of operating days now, since it's the same core in the IPro, BP, and VVPV.