Acebeam H15 18650 xhp70.2 headlamp issue

Got this guy in the mail yesterday. Tried it outside and it worked fine. Once inside in a room with zero light I noticed a very very faint light coming from the led while it is turned off. If I unscrew the tail cap this faint light goes out. Tighten it back up and it comes back on. This happens with various unprotected 18650s. This also happens with the protected 18650 it came with but it’s even fainter.

It’s so pale that I have no problem looking directly at it in the dark. Must be a fraction of a lumen. I noticed it’s only coming from one of the four sections of the led too.

Also noticed that if the battery is low this doesn’t happen. I think it was about 3.2-3.3v no load when I stopped noticing.

Sounds like a parasitic drain issue

Just measured the parasitic drain to be 0.11ma with a fluke 179 dmm. While that is low in the grand scheme of things taking years to drain cells, it seems high vs normal doesn’t it? I get parasitic drain from the control circuitry, but not from current running through the led.