XP-G2 Direct Drive off 1xCR123 or 2xAA?

Hi all.

I managed to source a few XP-G2 on copper sinkpads for a mod, and have some left over.

Would these work fine on a fresh CR123A direct drive, with absolutely nothing to control current or voltage?
Datasheet says 2.8-3.1volts.

Any idea what kind of current the LED may see with this setup? I'm curious with runtime as well.

What I'm planning is to build a moderate/low power dropin to use in a G2 with a dummy CR123. Or maybe two AAs in a G3.

RobertMM said:

Any idea what kind of current the LED may see with this setup? I'm curious with runtime as well.

Click to expand...

Check out current versus forward-voltage graph on page 6 of the datasheet:

http://www.cree.com/~/media/Files/C... Modules/XLamp/Data and Binning/XLampXPG2.pdf

Works just fine, current pretty much limits itself because the battery voltage is way under the spec voltage at say... 700mA, which will require about 3.8V. Put a fuse in between your LED and your CR123A, so that if your LED does fail short [unlikely unless someone forgot heatsinking] your CR123A will not overheat.

You can, but as has already been stateddue to a current causing the battery voltage to drop, if you start with two good 1.5v cells fully charged, they may start off at 2.8v and go down from there, 2.8 I where the xpg stops working. 1.5v 3aaa cells do give a good output not too much current without a resistor, at about 450ma if i remember correctly, its why head torches use that configuration most often, as you do not have to regulate the voltage or current by a great deal leading to great efficiency. Aa will drive more current through for a while, but not lots more, and once they get past 2.8 v the lights go out anyway.