Robatman said:
hey sfCyclotourist
I'm getting close to taking the plunge on this, but i'm not sure on whether to go with 2 or 3 cree's. Whats your run time like?
Having done it (and assumed ridden with it) would you do 2 or 3 if you did it again?
Also did you use a lense (eg ledil) or just reflector and cover?
Robert
I haven't done extensive/serious run-time testing yet, but I should get at least a couple of hours on the higher settings, and I'm hoping a lot more on the lowest setting.
Whether or not you use 2 or 3 Crees depends on what battery you have or are planning to get. I used 8xAA's because I already had 'em and I wanted to minimize costs and size/weight. One of my design goals was to clone the Dinotte lights, which use 4xAA NiMH (and a custom boost/buck driver circuit, I think). If you already have a bigger battery (14.4 LiIon, for example) then go w/as many LEDs as you can, I'd guess.
Add up the forward-voltages of the LED(s) and driver circuit and see what battery voltage you need.
I haven't ridden with my light yet, actually! I hope to try it out on the commute home tonight.
My next light will probably be a single hi-bin Cree in an ultra compact housing. I originally wanted to make my light modular, with a primary housing containing one Cree+optic, the bFlex, the main DC power jack, and the control button, with a secondary housing containing only a Cree+optic optionally plugging into the primary unit via a second switched DC jack -- that way I could use either 2 LEDs for brightness or a single LED for long run times, but at the last minute decided against it due to the complexity -- and also because you can simply run the (multiple) LEDs efficiently at less current for extended runtimes.
I didn't use a reflector, I used a collimating optic similar to the Ledil (mine's an L2, slightly larger and round).
see
http://yojimg.net/bike/equipment/lights/led_lights.php#parts for a rough parts/source list.
