How long should they last in use?

I got a night vision monocular for Christmas that uses these batteries. I have bought 2 packs of them since then. I only used my monocular a max of 10-15 minutes each time and I turn them off each time I lay them down and use my regular binoculars. Since the first pair went dead after 2 uses, i pulled the second pair out of the monocular after use thinking it woukd help, but it didn't. These batteries are very expensive, why do they not last longer? Do you make a battery this size in rechargeable?