I read that someone here reached 2000mA with a Cree XR-E led...

Well, I need to obtain the best brightness, even for short time, from a Cree XR-E Q5 (or other top-class) led necessarily using 2x AAA lithium batteries (those of my laser pointer!).

I read that for obtaining the highest current (mA), and therefore the highest lumen, I need to use "direct driver". What does it mean? that I have to connect the batteries directly to the emitter? what mA value can I expect from 2xAAA lithium batteries?