I was just planning on making a homemade led lantern and have been messing around with the direct driving the xm-l led. I used 4 eneloop nimh batteries totaling 5.6 volts. I measured 3.3 amps of current going to the led. Is this too much for the xm-l led to handle? I know that the xm-l is rated to handle 3 amps of current. Also what is the led Vf? Can anyone explain that to me and how it would effect my direct drive setup? Also the led is mounted on a cpu heat sink so I am pretty sure that should be adequate cooling even though I have not done any long term test.
Pushing it a bit but it ought to be OK.
Vf ought to be around 3.3V or thereabouts.
Cooling ought to be adequate.
I'd try it on three cells and see what the current draw is then or try a 3x2 setup with two sets of three batteries in parrallel as that would reduce the load on the batteries.
The current should be quite a bit lower at the lowever voltage, 3.6v would be the nominal voltage but check what you actually get underload.
And post some pics when you're done if you want.