Buck puck is a buck driver (drops voltage).. it's entire purpose is to drop the voltage from the source to the voltage required by the LEDs.. it is an incredible driver i like it a lot and used it in two of my mods.. one that uses 13 NiMH batteries in series and one that uses 18 NiCD in series.. i actually haven't tested a driver yet that has higher efficiency and more stable current output.. something like 1% variance in current during a 6 1/2 hr full-power test... it actually was outputting like 10mA more when the batteries were at the cut-out voltage and my low-volt ckt shut it down than with full charge.
The buck puck DC model needs 1V overhead.. so you need at least 12-14V from the batteries to get full power to the LEDs.. hope you got or are getting the buck puck with the control pin.. you can dim it with very high efficiency... i can run my tri lux light for about 4-5 days continuously when i dim it down.
The one issue with your setup is low voltage cutout.. it's not built in to the buck puck... i don't know what happens if the overhead is not met, but it's coincidentally very near that will be the low voltage cut out you will need so it might be a moot point.. however i would build in a low-voltage cutout circuit.. i have a schematic on cpf specifically tailored for the buck puck.. do a search for +andrewwynn +low +volt and you should find it. (make sure you search far enough back)
Find a place to put a potentiometer.. you can get a nice 10kohm audio pot from RS with a switch that may actually fit into the normal switch hole of a maglight.. this is the switch i use on megasonic:
http://rouse.com/mega
Good luck and have fun; flashlight modding is addictive as you have figured out.. and though you meant 'addictive'.. addicting is also applicable in your case as you are in the process of being sucked in /ubbthreads/images/graemlins/grin.gif
I'm surprised by the relative lack of mention of the importance of low volt cutout with boost or buck driver circuits.. i do see people mention 'it's important' but i don't see many circuits or solutions.. i would have loved to have had a 'canned' solution vs build my own... i used a pretty crappy op-amp so i had to re-design it since i couldn't bias it to zero without a negative power supply, but i built two based on the ckt i posted on cpf and they work perfectly with the buck-puck.. they are designed to output 5V when the battery is low.. that voltage is fed back into the control pin on the buck puck which is high=off.
you can email me:
[email protected] with specific questions that wouldn't be useful to the forum.
-awr
