The H05S has a battery polarity indicator works awesome! It turns On when I open the battery cover and turns Off when it's closed. I really wonder how that trick is done. I see no connection-paths that would indicate the cover is open or closed.
After receiving my copy of the H05S, I also became curious. After some looking around, I realized that the + polarity light(s) never shut(s) off, w/ or w/o AAA cells inserted, until some internal charge finally runs down. The AAA cells have been out of my H05S for over 12 hrs, and although the red indicator light is dimming, it is not out, yet.
That red internal light that lights up the + indicators can been observed even when cells are inserted. There are two 'windows' on the left and right side on either side of the LED/lens, above the 'wave' window. An internal red light can be observed looking end on at the correct angle into the window to the right of the lens, IOW, from the right side when viewing from the front/lens. The left window remains dark.
So being further intrigued by this design, I opened up my copy of the H05S light. there are actually two tiny LEDs mounted on a PCB shining up to the + indicators for each cell. There is also a very small rechargeable cell mounted on the underside of the PCB to provide power for those LEDs and possibly more. A micro-switch provides the output switching. The PCB uses surface mount devices and is fitted together with the battery mount as a unit. Very well executed and built light.
I really only have a couple objections to the design:
1. the light has to be cycled thru all levels to off. if the 'wave' feature is not used.
2. the switch covering is quite tough to push on even though a nicely sensitive micro-switch does the switching. I realize that the intent was to avoid any tendency for the light to turn on when dropped into a backpack, but, hmm..
belated correction: The 2 + polarity LEDs do in fact turn off when the cover is fully closed, and when the internal battery is charged. When I was observing the polarity LEDs, the internal battery had been running for over 12 hours w/o cells in the light. obviously not a normal condition