Thanks! Two of the sensors came to life with new batteries. My NYCE sensor appears to have failed: can't revive it.
If I can't count on reported battery levels to be accurate, then I'm really concerned about the leak detectors under sinks and shutoff valves, Pretty easy to know when contact switches on doors aren't working, but a non-working leak detector is an eye opener!
This is a device issue. I have some devices that stop working at 60% battery, and identical ones that work with battery showing 0%. There doesn't seem to be any rhyme or reason for battery level vs actual state.
One of the things you can do with those is get Device Watchdog (or something similar) and have it monitor their battery. CR123A batteries (lithium in general) stay flat forever and then just suddenly drop. Some devices will report them as 99 or 100% forever and then you get ONE reading below 99% (like in the 60s or 70s) and then they're gone.
So, if your devices are like this then you can have something warn you if they move below 99 because you know they're likely on the way to that giant automated home in the sky.