Yeah I was thinking that if I got 1300 lumens from it I'd be happy ...It puts out a lot of light....I will be content to change out batts.
I would think 1300 is an accurate guess.
If you allow much more than 4amps (@4.2V) to the light head - I think it will overheat and burn out. Using a higher voltage battery with many cells in series will give unpredictable results.
I guess i could look around the CP forums to find out what a 3 led torch will draw with the manufacturers recommended batteries. Then you could predict true brightness. But for bicycling - this is a bit of overkill.