[copied from my post in r/flashlight on Reddit]
I purchased three of Wurkkos’ new Golden WK03 flashlights for some relatives, so I can perform side-by-side comparisons of their brightness with charged and partly depleted cells to see if any of the output levels are regulated.
I held two flashlights side by side, one with a full cell and the other with a cell depleted to 3.3V, and compared their beams at short range. I do not have a light meter, but the Low through Turbo modes with the depleted cell are unmistakably (though not dramatically) dimmer than the same level on the full cell.
Moon mode, however, appears to my eyes to be exactly the same brightness with both cells. I even swapped the cells and made the same comparisons of each level. I also noticed that, as the cell depletes further, the step up from Moon to Level 1 becomes very small, which again indicates that Moon is maintaining its output while the next level is diminishing.
So it seems this light is unregulated, but maybe Moon mode is regulated? I don’t know enough about flashlight drivers to conjecture as to why only Moon mode maintains its output.
If anyone would like me to perform any other experiments while I still have these, let me know. I don’t have a good place to photograph beamshots, though, or a proper camera to do it with.
I can say that the beam is not great. It has a large, sharply-defined hotspot with a yellowish tint shift into the corona, and a spill consisting of three sharply-defined brightness zones. The spill is also fairly dim and narrow, providing poor peripheral vision. Boaz’s DC-Fix diffusion film made the beam profile perfect.