I just tried the high drain 650mah Olight 14500 in mine and it fit, however this Olight battery has a very low profile button top and I seem to remember other Olight cells with a much more prominent button top that would add more to it's length.
To answer your specific question, I usually use Efest 700 mah IMR 14500 V2(red) or the Efest 650 mah IMR 14500(purple). IMRBatteries has been a reliable source for batteries for me. They have sales quite often(if not on sale the 14500's can be a little pricy $6-$7). Because of a lot of users reporting significant parasitic drain, I always store my EA11 & my EC11 with the tail caps loosened. Not only does it protect from parasitic drain, but when you tighten it before use the flashing red battery indicator always let you know how much juice is left. Good luck!
http://i958.photobucket.com/albums/...ghts/16FA17C0-D8C7-43EA-ADD6-6999269B9429.jpg
