I just replaced the batteries in my two multipurpose sensors. They were completely dead - one read 0.01v, the other 0.2v!
Neither of my multipurpose sensors getting open/close events – they are just using the stock DTH and I’m logging the reported temperature, which I’m pretty sure is a passive activity (it wakes, reports). As I said, one made it 6 months, the other 9 months, which is I suppose is pretty decent. But they kept reporting 66% battery even when there were no events coming in anymore.
I use several things to monitor devices (Device Monitor, Simple Device Viewer, Battery Monitor) and I didn’t pick up on when these stopped reporting events, which really sucks.