Got mine Wednesday from the good folks at Lighthound, this thing is sweet! And the Solarforce LED head rated .8~4.7V promises some long runtime. But I've got a question concerning batteries. Right now I'm running with Energizer Lithium cells, but is anyone using Lithium Ion cells in an L2r? Say a single cell with a dummy. Ohms law is should work, but there is the real world.