Why not order a flexdrive buck/boost from DTR? It’s a great driver for case neg diodes as it is cont negative itself. I have a couple pens using this driver w/ neg diodes and set to low currents. So low they’ll run on AAAs.Just a linear for a mitzi 660 at ~350ma
What driver would you suggest running on a 18650 Batt ??I suspect the diode you are trying to drive is the ML101U29. It has a very low Vf. If you were to use a linear driver with one or two Lipo cells, it wouldn't be very efficient as much of the excess voltage would not help in driving your diode. The current the diode pulls would also be expended as heat in your driver too.