I just took the Tadrian lithium thionyl chloride 3.6V cell out of my Tektite Micra Lithium, and popped it into my Arc AA. I expected the Arc to be about the same brighness, but it was DIM DIM DIM!!! /ubbthreads/images/graemlins/icon15.gif I could look directly into the LED without discomfort. /ubbthreads/images/graemlins/frown.gif When I put a regular AA back in, the Arc was back to its good old bright self. /ubbthreads/images/graemlins/smile.gif
If I remember, the Micra Lithium only draws 9.6mA off a brand new Tadrian cell, which is much more appropriate for that battery than what the Arc AA needs.