Soon after I got my FM (42 years ago) I started using the lithium batteries. For the FM, as long as there is enough battery left to get the meter to work, it is supposed to be right. Though less conveniently, the low-battery indication is when it doesn't work. March last year (just before ...) I was out with an FE2, when the shutter stopped working on the 36th exposure. It seemed a good time to rewind, but then I remembered why it stops working. Yes the battery was low. OK, reminded me to get out my (not black) F2AS.