No, I'd like to shut it down when the network rack UPS is getting low (via the USB connection on the UPS).
Putting a power bank on the hub is just going to extend the time it runs, but won't shut the hub down gracefully when it runs dry.
I don't care so much about keep the hub running during a power failure as there's very little it could do anyhow if there's no power. Of course, extending the runtime will handle longer power outages before the hub does an uncontrolled power down. As a practical matter, maybe that's all that can be done.
FWIW, the Cisco unit I used for testing has a nominal power rating of 195 watts. During testing, the unit had 20 watts in use, leaving 175 watts of head room for the splitter under test. The peak power consumption of all the splitters tested was 2.6 watts, and most peaked below 2.5 watts. That's really a trivial load.
I cannot speak to everyone's configuration. However in my case, I am fairly confident in saying that available switch power was not a factor.
I looked but was never able to find a solution for that. I ended up getting a used SMT1500 with network card and @kahn-hubitat's driver to do what you want. Thread is here: APC SmartUPS Status Device
You can definitely use the NUT driver to do this. You just need something to run the NUT server on. If you have an always on PC available in the rack, then that's easy enough. If not, you can always setup a Raspberry Pi Zero 2 W with it. I just set this up like two months ago. Raspberry Pi Zero 2 W, power supply, SD card, micro USB OTG cable, and (optionally) a case. Hook the UPS USB to the OTG cable.
I have the UPS plugged into a USB port on my NAS, which is the most important thing in my rack as far as shutting down cleanly goes. Perhaps I could run NUT in a container on the NAS, but I sense a rabbit hole opening up here...
It's from the same company as the power pack @snell mentioned; hopefully it is always-on as well, and it's certainly going to be able to keep the hub powered for a lot longer than the rack's UPS will. Doesn't help with a clean shutdown, but the power seems pretty reliable here (so far).
You are already running NUT on your NAS and do not need a container. Synology uses NUT to manage the UPS.
If you are running DSM 6, there is nothing you need to do to enable a remote client. If you are running DSM 7, you need to allow the remote client's IP address. To do this, go to Control Panel -> Hardware & Power -> UPS -> Permitted DiskStation Devices
and add the IP address of your hub to the allowed access list.
Then install the NUT driver on your hub, and configure it like so:
@dennypage - Great work at getting to the root of the issue. Even though I do not use Z-Wave typically, I decided to compare my C8 hub's Z-wave performance using my old UTRONICS PoE splitter versus the Procet Gigabit Pt-PTC-AT PoE splitter you recommended. Both were used with a UniFi 8 PoE 60W switch.
While Z-Wave, connected to a single GE Switch, worked with both, the old UTONICS caused some small, random delays between the hub sending the command, and the switch acting upon it. With the Procet splitter, the results were consistently quick and reliable.
Just another data point! Thank you for the extensive testing and for publishing your findings!
