As I reported yesterday, I just noticed I had 2 Multipurpose sensors with dead batteries; one died at 6 months and the other at 9 months. However, both were still reporting they were at 66% battery. The response from @csuk(SmartThings) was really valuable.
BTW: I don’t believe I have “weak meshes”. I have an Iris outlet (which repeats both Zigbee and Z-wave) near one, and both an Iris and SmartThings outlet near the other.