@JohnRob and I have started a new project to design and build a USB-C UPS specifically for Hubitat.
This project will be fully open source - it’s heavily based on the design by Beyond Logic.
This is the place for discussion on this project.
First draft of the schematic;
Design goals:
Feedback on these goals is very welcome, we fully intend to try and keep costs down as much as possible, so expensive suggestions may not get added to the list.
Ps this is the Existing shutdown method - hopefully we can remove the guess work.
Thanks mate, I’m grateful that John is involved as my knowledge of EE is at hobbyists levels.
Can we have a spot for this on the top of the hub ?
@njanda sure, let’s get the eCad design locked down, then I’ll take a swing at case designs.
Just keep in mind that the light pipes are 3D printed from transparent PETG, so they do have more limitations than injection molded plastic.
They’re Friday night ideas and you know, I’m sure some of the best ideas were Friday night ideas.
Unfortunately most get thrown out with the empties 
I might keep that Harmony photo as nostalgia, for when they are no more, and I'm buried beneath a pile of remotes in my Living room
Harmony, dude, harmony remotes aren’t in the same league as my URC MX-980’s + MRF-350’s RF Base Stations .,.,
… And because I’m cheap, I bought them 2nd hand for a 1/10th of their retail price.
very cool idea.
I've seen some projects where power failure triggers a safe shutdown routine on the hub.
would the power failure monitor have enough juice to run a tiny relay output to drive external contacts? That way you could hook up an external Zigbee/Zwave contact, without having to build it into the device.
A solid state relay could certainly do that, John and I have just started down the rabbit hole, so we’ll have to see what we can come up with.
Ahh my bad. I'll have to take a look at those...
All good, I’ve just polished off half a litre of JD 40 Vol so I might be less comical than intended. 
PS the loss of harmony sucks, that’s why I’ve been buying URC remotes from the used market.
Need more than a relay. Need some kind of battery life reporting so hub can be shutdown gracefully before battery expires.
Quite true, currently you need to guess how long the batteries will last, there’s also the shutdown time for the hub which can be around a minute or so.
We’ll certainly see what is possible without making this drastically more expensive than the OG version.
Interested also. Plus, I would be even more interested if you plan on an expandable/modular design.
I have more ideas but I think the 1st of these is problematic enough but also the most important in my book.
EDIT:
For the casing, feel free to look at my thingiverse Hubitat wall mount or such. The OpenSCAD file is posted there so it has dimensions and other information that might be useful.
Just a word about the UPS controller for this project.
The core "brains" of the UPS is an full ups system IC PN: LTC4040 from Linear Technology/Analog devices.
This device is the "Cadillac"** of UPS controllers.
What I appreciate most is the ability to limit battery charge voltage. By reducing the charge voltage a little power is lost but is much better for the battery life. All the other battery charge IC's charge Li-on to the battery max of 4.2 volts. Then they hold it there for basically forever (as long as input power is present). This is a worst case operation for a Li-ion battery.
Other leading particulars:
** this may be a dated reference 
John
Even "down under", we get the reference. 
Not for this audience.
Download the Hubitat app
