If it turns on in your pack then you might not be turing it off "hard/firm" enough.
Taking the batteries out while transporting the light to/from the cave is another option. That's even an option for in the cave.
But yeah...like Scott already said...check out some of the newer lights. I know with my Zoom Zora I used to change batteries ever 2-3 hours but with these new Apex's (as low as $55 according to
Froogle) you get a constant light level (cause it's regulated) for 12+ hours (on NiMH's or 17 on Lithiums).
Bryan