and a metal cell holder that I soldiered a micro switch to. I then attached it to a Pelican brand replecment Xenon lamp module for a 3 C cell flashlight
Screwed a strip of metal to the module and stuck some sticky back velcro to it and my helmet.
Its a ultra light wieght very bright and last for about 2 hours head light. The battery sits in a vent of my helmet..lol I hope thats safe..lol.
You could run 3 AAA or AA cells in a holder and velcro it to the back of your helmet or put it in your back pack or jersey pocket.
Or this $1.50 3 AA cell holder with built in switch