Thanks for the feedback. I checked my solder joints to the pill and one was cold and already came loose. I re-did them using flux + rosin core solder and soldered it in 4 spots, making sure they wetted out. Should hold up now.

Paired with the 18650GA cell, really pleased with the light thus far.

Could I use non-protected cells or is it generally a good idea to just always use protected cells (for this NCA chemistry at least) ? I was not sure if the driver would cut out with the guppydrv firmware, but it does at 2.8v based on my tests.

A few more pics: