I’m hearing that some of you are experiencing battery life and mesh stability issues with z2m. The first thing I want to make clear is that this is NOT a problem with CORE. While I initially had these issues with z2m on CORE nothing has improved since I moved z2m to one of my servers.
Battery life: Most notably affecting Iris v2 motion sensors, but ST water sensors are also suffering to a much lesser degree. I’ve had a handful of the Iris sensors in my mesh for over 3 years, first on HE, then moved to CORE. The original batteries that came with the sensors I got through eBay had never been replaced until sometime after moving the mesh off of HE. At first I figured they were just old and would have needed replacing anyway so I didn’t think much of it until the new batteries (out-of-the-box open-circuit voltage around 3.25) dropped to 2.7V in less than 3 weeks. They are very close to being useless at that voltage. I tried another round…then another, with the same results. A few weeks ago, after working with the z2m dev for some months (see below), I gave up and moved all of my Iris back to HE where they have been solid, with no drop in battery%, ever since. At the dev’s request, after he made some promising changes, I added a spare Iris to the z2m mesh again and the battery life indeed was some 30% better…meaning it lasted 4 weeks instead of 3. 
I expect few will read the mangled issue cited below so I’ll summarize: I ran numerous zigbee packet captures over a few weeks, both on the z2m mesh and the HE mesh, and compared them (controller/system startup, device pairing, cycles of operations from steady-state and alarm/clear), looking for whatever HE is doing differently in the hopes of identifying what could be done with z2m to remedy the problems. The z2m dev taught me a lot about how the communications are supposed to work and he spent a good deal of time analyzing the packet captures I posted. While some incremental improvements were made they did not have a substantial impact on the cited problems
Stability: Again affecting the Iris most notably but also the ST, I had devices going mute, where they’d still show in the z2m map but hadn’t “been seen” for days/weeks. Oddly, the ST water sensors would still report when wet but remained unseen and no temperature or battery info would be sent. 
The Iris were completely mute. With both devices, they sometimes could be un-zombied simply by pulling the battery and re-inserting it without delay. Other times they needed to be reset, and sometimes they had to be force-removed from the z2m mesh then reset and re-joined to get them to behave. I never did discern a pattern that indicated which of the remedies needed to be employed. Again, no such problems once they were moved back to HE.
It gives me no joy, although a good deal of peace of mind, to have HE be the best option at this time. As we all know, there are other shortcomings of the HE zigbee environment but stability and battery life trump all other issues IMO.
I filed an issue with the z2m dev and we tried several remedies. Unfortunately, and completely my fault, the issue became muddled with unfocused posts but the gist is as I’ve summarized above.
At one point Koen found a misbehaving repeater (ST plug-in switch) and it was removed temporarily from my mesh. Then, for good measure, I temporarily removed the rest of my ST plug-in switches leaving only a dozen of Iman’s Multi-sensors as repeaters and the mesh was in great shape without the ST repeaters. Then I added the ST plug-ins back to the mesh and was a bit surprised that not a single end device chose to connect through any of them, preferring to stay with Iman’s Multi-sensors even through various events like power outages. In my experience Iman’s Multi-sensors are the best repeaters with the caveat that I’ve tried very few others not mentioned above. YMMV and standby for someone to say they are crap and must be disposed of for a healthy mesh in 3…2…1…
I’m still moving zigbee devices back to HE but I had complete stability with great battery life when everything was in the HE mesh before and I expect it will be the same in the near future.
