I have seen people refer to using Lithium AA in their Fenix L2P. Has anyone had trouble with this, the paper that came in the box with mine says do not use lithium because the higher voltage could cause damage.
3.7 volt Li-Ion is the issue I believe. Energizer and Battery Station Lithium AA cells are a little higher than alkaline cells (by about .2 volts based upon my voltage meter) but shouldn't present a problem.