Well let’s do a little bit of maths here.

The XP-G2 emitter, as tested by Match requires 1800mA just to get to 500 lumens. And that’s the emitter. Factor in a 80% reflector loss and to get 500 lumens out the front, the emitter would need to be pumping 625, a theoretical impossibility unless one bumps the current to 2100mA and uses a copper star.

But we’ll assume the seller means emitter lumens. So that’s 1800mA the emitter needs. At 1800mA the forward voltage requirement of the XP-G2 is 3.2V. Multiply current by voltage and to put out 500 lumens the emitter needs 5760mW. Two standard Eneloop AA’s have 1900mAh each and a nominal voltage of 1.2V. In series, a pair of them have a total capacity of 4560mWh.

So the emitter consumes 5760mW per hour, and the batteries can only supply 4560mWh. Total runtime on high, as I calculate here, is just over half of what they claim.

And either way, the driver, if it can supply 1800mA at 3.2v for the emitter, will be sucking 2.4A off of a pair of Eneloops. Pretty harsh even for those tough suckers.