What kind of features would you want to see in a quality rendition of a wind up light?
I've modded a cheapo wind-up light to get it as close as I could to my ideal; it's not quite there, but building the ideal one would entail spending big bucks for a custom body, custom electronics and all, so I'm leaving that project for a distant future.
I got one of
these, then made the following mods:
1) swapped the generic LEDs with Jeled 55cd (would have used Nichia GS, but I don't have enough to justify using up three in a cheap emergency light). This yielded an impressive boost in brightness (and a corresponding drop in beam quality, but I don't much care about that)
2) added a JST connector to the little 3xNiMH pack inside, so that I can charge it from outside using my bench power supply, and only use the crank if I actually need it; this allows me to use the cranking mechanism a lot less (actually I haven't had to use it at all after the mod... yet), which in turn ensures that the plastic gears in it will last much longer.
3) swapped the original resistors with less restrictive ones; it used to drive the three LEDs at about 15 mA each, but now gives them 35 (IIRC) from a fully charged battery. This has given the light another increase in brightness.
4) swapped the switch with a three-stage one, and changed the connections so that the other stage routes the circuit through much more restrictive resistors, that feed about 20mA to all three LEDs (6.7 mA per LED).
I'm pondering swapping out the tiny NiMH battery with a LSD AAA pack; there should be enough space to shoehorn the AAAs inside the light's body. That would give it much better runtime, and the bigger cells would be less bothered by the rough charging they get from the DC motor.
So this is my crank light. I don't think you can make a better one without spending a lot of money on quality components.
As for my ideal crank light, I'd want it with:
1) a waterproof, floating body made of metal or damage-resistant plastics, with some sort of magnetically coupled crank
1a) reed switches for operation
2) a brushless generator
3) a solar panel
4) internal circuitry to control charge level and maximize the life of the battery
5) A123 LiFePO4 cell for power; as far as I know, it's the most durable chemistry that you can actually buy
6) underdriven Cree R2 for improved efficiency
7) multimode driver, with power controlled by one switch and modes by another; neither switch should be easy to move by mistake
8) being an emergency light, I'd like to have strobe and SOS modes on it, but they'd have to not get in the way of normal operation. Also, SOS should be made to work properly; real SOS morse code is much faster than what we're used to see in multimode lights.
9) external charging contacts in the form of magnetic pads (think Photon Rex); they could also be used as power sources for small gadgets, though there should be some form of short-circuit protection in that case
10) A low-power green laser diode, as the beam's high visibility at night would be useful for signaling your position
Such a light would be lasting. You could charge it quickly with an external power supply, the solar cell would keep it charged indefinitely as long as there was light (or it could charge it slowly if an external power supply wasn't available), and if neither external power nor light were available you could just crank it. It'd have no openings for water to leak into, the A123 cell would last many years and would give it great runtime and the interface would be easy to master.
I'm pretty sure it'd end up costing several hundred bucks though...
. It was an OK light electrically, but mechanically the gear drive mechanics STANK!! soft plastic gears that softened and slipped after ~15 seconds of turning. Eventually I ripped out the gears and hard soldered some alkaline AAAs, threw it away once they died.
