The full review is available here
English review at BudgetLightForum
German review on my website
Summary
When you first see the Nitecore EDC31, it may not appear that special. But a closer look reveals its special secrets. A compact EDC flashlight with a touch of tactical flair, a rather unusual LED with nine dies and a super simple control scheme with a two-stage electronic switch. While most modes are optimized for throw, the “Lumin Shield” mode impresses with a bright and floody wall of light. I also like lockout with a slide switch, called “Rapid Lock”.
Given the compact design, it is not surprising that the flashlight heats up quickly and cannot maintain the high brightness for long. In the lower levels however, the constant current driver keeps the brightness pretty constant. Unfortunately it is not possible to choose freely between the wide and narrow beam for each brightness level. The permanently installed rechargeable battery can also be seen as a disadvantage.
Yeah, I'm a fan of Nitecore, and the lockout switch is really nice, but I can't forgive them for using a non-removable battery.
Flashlights, of all things, have no reason to use permanent batteries.
There's a battery for every flashlight form factor imaginable. Inexcusable!