I made one of these a long time ago because I got sick of purchasing so many C cell batteries and only getting an hours worth of ride time out of em..
Heres what I did..
I got an old water bottle..
I went on Ebay for an old Cateye HL-500 (2 C cell headlight) $6.99 shipped
I bought this because I like the beam pattern..
Then I went to Radio Shack for a 7.2V R/C car 2000mAh ni-cd battery /charger combo
Model: 230-0322 $24.99
R/C car wiring harness w/crimp connectors
Model: 23-444 $4.99
7.2v 700 mAh bulb (sais 600mAh on site tho?) fits right in place of the factory bulb.
Model: KPR118 $1.39
I had some misc 18 guage aug outdoor wiring/speaker wire..
I modded the internal housing of the headlight to run wiring back to a water bottle where the 7.2v r/c car battery is..
So for less than 40 buckswith this setup I get a solid 3+ hours worth of run time and its rechargable..
If I could find this style of bulb in a Xenon, I'd be set..
Heres some pictures.
Inside the headlight housing..
I have it wired so that the stock switch is used to actuate.
housing mounted on bars
backside of housing showing whre the wiring exits the housing..
Wiring passes through the drinking part of the water bottle to the battery (niterider style?)
Light output.. (its not aimed directly at the camera, its just how it looks..
there ya have it, just thought I'd share..