If you wish to make by yourself a powerful lamp for your night bike rides, as some beautiful lights
you can buy, the best choice in my opinion is to build it with a commercial LED lamp. Since some of these lamps work with 12V AC current, I decided to use as power source a 12V DC Li-po battery. The lamp has an included rectifier which converts current from AC to DC, so using a DC source works good here.
NOTE: I made this projects specifically to have a powerful lamp to mount for a night ride. All the connections, the meter, the lamp pins, the battery terminals, are NOT waterproof, neither water-resistant. For the same reason I don't need any power switch, and I need a fast to plug lamp support. Pay attention to use a so much powerful battery pack with rain or wet hands!