This thread by tecmo kept me busy: 100klux in a pocketable light, is it possible? I thought for a while about good hosts, suitable leds, Sinkpads, right amperage, but what still would be a sensible and usefull flashlight (I'm not scaru I'm afraid, I'd love to be scaru but Im just not him ) and decided on the following build:
This is as small as I could made it and still have a usefull flashlight:
It is the Uniquefire UF-T20 aspheric. It is a relatively small 18650 aspheric, but is it really pocketable? For me it is not, but for some others it is.
The stock light is well build, but comes with a XM-L led. Some claim that it is a good thrower, but I think the throw of the stock light is pathetic, I did not have one by hand, but I'm sure it is out-throwed by the Sipik sk68, even though the light I received ($20,97 Manafont) runs the XM-L properly at 3A (it did give off the weird smoke that some others have described fot this light by the way, don't think it is the lube, rather the heatsink glue).
You just don't want an XM-L in your aspheric thrower!
But apart from the wrong led and the initial smoke this light is nice: everything is solid, it can dissipate the heat from a led at 3A (unlike most (all?) other XM-L zoomies), the glass (some have said it is plastic, but it actually glass) aspheric lens has a decent curvature (=short focal length=>still close to the led when fully zoomed in=>so still cathes a good portion of the light when zoomed in) the actual used diameter of the aspheric lens is a solid 32mm (bye bye Aleto ), and it looks to me much better than any inflated version of the Sipik sk68.
I still had the XP-G2-3C at hand that I accidently had dedomed (living for a while quite nicely in a Romisen RC-G2, sorry Romisen..), and I really like the tint of it (~4000K), even for an extreme thrower I want my tint right . I reflowed it on a 20mm copper Sinkpad, had to sand the sides a bit (the UF-T20 pill has only room for 19mm) and decided not to use thermal paste but just reflow the whole thing onto the brass pill; good for heatsinking and it saves me the trouble of screwing down the board:
As you can see at 1.05 minute the solder paste melts and the board sinks in a bit. Unfortunately not really level, so after this video I heated the pil up once more and while still hot I pressed the board down on the pill with a forceps. I added a 3.05A Nanjg 105C driver, a blob of solder between driver and pill for electrical contact (brass pills are nice to work with!) and the flashlight was good to go:
beamshots: resp. flood at 2m, zoomed at 2m, zoomed in at 5m, outside tree=30m, outside grass=100m
You can see the clean pencil beam. I did not have to blacken the area around the led because the led was dedomed, so no light is scattered backwards to the board via the dome. Sorry for the hasty outside shots, I think my neighbours find me weird enough for now.
And now for the numbers:
The estimated output in lumens (calculated from ceiling bounce readings), with a freshly charged Panasonic CGR18650CH inside:
flood 440 lumens, zoom 280 lumens (=a decent 63% of the flood output)
I did a 10 minute testrun, after 10 minutes the light did not become any hotter anymore, so heat production/dissipation had balanced out, it was hot but still not too hot to touch.
Throw is a lux-measurement of the hotspot at exactly 1 meter from the top of the lens. (I also tested at exactly 2 meters and those readings were a precise 4 times less (I measured 27.000 lux at start), so I decided measuring at 1 meter give correct numbers ).
I have the impression (I don't know why) that my luxreadings are on the low side (luxmeter: Tondaj LX-1010B). I have never been able to calibrate it to a known light source. (Fun: this luxmeter claims on the housing to measure up to 50.000 lux, but the actual reading goes over 100.000 no problem)
The tailcap reading at start was 2.97A, battery loaded to rest voltage 4.21V
throw at start: 108 klux
throw at 30 seconds: 107 klux
throw at 2 minutes: 105 klux
throw at 5 minutes: 101 klux
throw at 10 minutes: 101 klux
The tailcap reading after 10 minutes 2.62 A, battery rest voltage 3.87 V
It appears that this build is indeed able to throw over 100.000 lux@1meter, jeehaw! And the light is still kept usefull: runtime on 1 18650 will be about an hour on high (depending on battery type), the light can indeed run on high for longer periods while maintaining output (so the heatsinking is good), and whenever you don't want a pencil beam (this may just happen occasionally ) there's always a nice 440 OTF lumen flood option.
I have almost forgotten the beam of this light when it had the XM-L in it .
Thanks for reading!