My multiple firsthand testing with what I use is:
#1 - 8AAs  will easily last me 2 trips ~5hrs a day so.. 100+ hours.
#2 - Forget to turn it off at night in an overturned canoe and I consider myself lucky to hear the low battery warning in the morning.

A favor Magic? Can you test the bonehead current draw when forgetting to turn 'em off and pinging the Milky Way all night?

Since I'm the weakest link. For me that means 16 LI AAs per trip so about a half pound of batteries... plus FISH LO-K-TOR.