Gabe,
For what it's worth, I posted several long posts on batteries on the old forum. I will do an all inclusive one here when I get the time. I use Eveready 2500 Mah NIMH AA cells in my Explorer II. I get about 14/15 hours with intermittant backlight use. Before changing to another set of the same cells. I have never run to the low battery alarm. I carry my spare fully charged cells in my toolbelt just in case. NIMH cells can be topped off anytime without any "memory effect", and should be stored fully charged. After a hunt, I switch cells and recharge the ones I have just used, thus giving balanced use to both groups. The difference of "in use time" is dependant upon the capacity of the cells in Mah. The increasing capacity of the rechargeables is now surpassing the alkylines. The rechargeables will drop off quickly at the end of their charge, the disposables will slow down a little more gradually. I don't know of too many people who detect for more than 8 hours at a time, and I'm one of them.
Bill