how many lumens does the L5 put out?. What power are the other four settings? Can you get a second battery pack?

Hey greg, There are 4 settings Hi ~ 80-100 lumens.. Med ~ 45-60.. Low ~ 10-20, and strobe ~ 80. These are just estimates! I did not use any instrumentation or calculations these are simply personal estimates (I do own rated 220/30 lumen LED, 3,500 lumen HID, 60 lumen incandescent and many others!). The battery back lasts a very long time even at high setting. I have used it extensively and have not had an issue with step down voltage to conserve power. I am not sure what happend to Cowboy but other reviewers and gear junkies like myself did not experience these issues. The actual headlamp is 4 oz! Incredibly light no batteries on head or anything, the battery pack does come close to a pound, but you can put it on your belt or the belt that comes with the lamp. You wont need an additional battery pack! If you really wanted too (not be worth your time) you could modify this light and add a slightly more powerful LED and two battery packs, but not for the average joe. Now my only real critique is the housing of the battery pack it is not water-tight. So make sure you have it under your waterproof layer just in case, but the headlamp is water-resistant/easily survive rain and snow, not for scuba or diving! Hope that helps, honestly it is a pretty beast headlamp, if you find it on sale go for it you'll be stoked and your friends will be jealous.