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!
Step 1: The Lamp
I bought in a shop a 4 cree leds 6W lamp, but of course I can change it whenever I wish with a more strange or powerful LED spotlight. You can determine your best choice also referring to the beam angle. You can find an angle from about 30° to 60°, remember that a narrow beam will light further, but street sides will remain in darkness, the same as road signs.