Had a cheap BSA on mine one year till the battery compartment cap decided to fly off and was lost. 2 things I learned:
1) you can't hit a thing with it with the red dot off (be it lost like mine, or a dead battery); and, 2) ended up taping a quarter
over new battery/compartment (which worked, but red dot stayed on) till got thru the weekend hunt. Never again, I went to
a quality, low power variable (Leupold VX-II 1-4x) and never looked back...