""hub that has not come back after power outage""...we hear it time and time again!

Running Linux under EXT4 with journaling pretty much got rid of corrupted filesystems on power loss.

I hope you are looking good when your operation is over :grinning:



Thanks mate, I’m hoping this is that last medical issue for a a decade or two :rofl:

Here's hoping everything goes smoothly tomorrow!

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Just for fun, my system is running on an APC UPS650 that i pulled out of a dumpster about 2 decades ago. ?3? Batterys later, 2 ring repeaters shut the system down on power failure after a half hour of no power.
And on the other hand, had a corrupted database reported on a C8, during a normal low memory reboot the other day.
No telling...

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Thanks mate, it’s a fairly straight forward and common operation, so I’m expecting a good result.


I run UPS’s too, but they are only good for short duration outages.

If you rely on Hubitat for your security system, 8+ hours is much better. All my door locks, sensors and sirens are all battery powered, so keeping my hub online during a power outage is ideal.

I use the below and have had a positive experience thus far. 3 of them cover one of my C8s (the other one is covered by a more powerful/commercial UPS), the AT&T fiber<->Ethernet transceiver in my garage, the Z-Wave power meter in my exterior Generac electrical box, one of my satellite Orbis and my cable modem (some obviously collocated). So far, nothing but praise wrt/ eliminating Florida power norms that include spikes, brownouts, etc.

For longer-term outages, of course, my Generac kicks in fairly quickly so tough to say what their longevity is depending on draw so value/mileage may vary per your scenario.

Amazon.com: Shanqiu Mini UPS Battery Backup Uninterruptible Power Supply for Router, Modem, Security Camera with Input DC Output USB 5V DC 5V 9V 12V 3A (74Wh) : Electronics

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The LTC4040 UPS design is costly because the LTC4040 IC is really expensive. When @dJOS made the original boards I think the LTC4040 was in the $12 range. Now its down to $8.50, still expensive.

The reason I originally became interested in a design using the LTC4040 was because it is the only Battery IC I found that could be set to charge to a voltage below the 4.2Volts that is "standard" for Li-ion batteries. However floating a battery at a constant 4.2 volts is bad for battery life. The LTC4040 also supports LiFePO4 batteries which are a better choice for a UPS.

Commercial supplies want the most watt- hours as they can get (aka advertise) they don't have much incentive to reduce the watt-hour rating for longevity.


And it also let us set the min/max SoC - in our case I configured it for 20/80% to ensure maximum longevity for the LFP / LiFePO4 cells.


My ASUS router does not even have an option to shut it down, you want it off you just click the power button or yank the plug out. Most of what it does is committed to NVRAM and lots of stuff runs in tmp files which are wiped when it restarts, but it does have some persistent JFFS storage. Not sure what file system the main OS runs on but my USB stick attached to it is formatted EXT4.

Never heard of anything getting corrupted on one of these routers :person_shrugging:
Maybe due to the file system or maybe just by design with the NVRAM.


@dJOS @JohnRob good on you guys for taking on the challenges, pulling this together, and not compromising. It's a great thing to see when Design, Engineering, and the Customer come together WITHOUT Marketing mucking up the deliverable or speeding up the timetable in the race to be 1st.

Best wishes on the health front. The real challenge we all face these days.


It's probably running a version of BusyBox- which is a 100% in-RAM version of Linux.

Yes, the ASUS routers run off BusyBox.

I read in another thread somewhere that HE may be based off BusyBox as well, but it was just from another user so that may not be correct.

Unifi Cloud Key (gen 2 plus) has become my limiting factor. It has a graceful shutdown that takes perhaps 30 seconds. It is anything but graceful when our backup generator kicks on.

Adding a CyberPower CP350SLG to the network cabinet this weekend. Even this is overkill, as I just need to bridge tiny transients. I had a Konnected UPS keeping our modem/router and C7 happy, so I will repurpose that somewhere else.

If the problem is database corruption then a stable filesystem won't really help.

Not trying to suggest DB corruption isn't real, however I think you are ignoring the negative effects on other electronics.

My PC = I unplug power and all my on screen info is lost and only restored to the last automatic backup for that program.
My NAS, printers, scanners etc all restart from some previous state loosing all in process data. 90% of my digital clocks have to be reset (probably the most painful for me).

So the equivalent to these would be for the Hub to automatically restore to some previous state. Would this be acceptable to you? I guess the Hub could run some sort of a parity check on the DB upon starting and only change it if found to be corrupt.

I sprung for a small UPS for my Hub and I have a larger one for my PC. These are only recent additions as it seems our normally reliable local grid has been experiencing more and more short term power losses.

#1 Priority is SHUTDOWN, quickly shutting down radios, Ethernet, and other high power consumers ought to leave enough room to get things done even within a pretty modest power budget, no?

Before purchasing my Hub UPS I looked closely at short term power storage. Although I can only work with the power the complete hub draws (i.e. cannot shutdown the radios etc) It turned out battery's needed to be used. No supercap etc could maintain the energy needed to hold the Hub up for a internally controlled shutdown.

the problem is most extenders switches are not so you mesh may not work well during an extended power outage even thoughg hub is up.

i use a couple of ring for zwave just for this reason so i still have hopefully some repeaters to keep the mesh marginally up.

for zigbee i put 2-3 sonoff dongles on battery backups for same reason.. but who knows i haven't turned off the whole house for extended times to try (would not garner very much waf)

just recently had the hub freeze totally after successful backup (another thread so far no reply from support) and one of those zigbee extenders is now offline even though it has a battery backup...
assume it went into panic mode as hub was hung for 4 hours before i noticed.

and i am not at the house, so now i have to put a usb switch on the extender so i can remotely reboot that as well.. always something..

I have a similar situation with our whole home generator. The gap between a grid outage and the generator coming on is relatively small but significant. Like you, I'm bridging the gap with (2) of these. One is for my study with my PC, Hubitat Hub, a 16-port switch, (4) external cameras w/recorder and an internal camera. The second is for my equipment closet with the modem, router, controller, another 16-port switch and a 10-port POE switch that feeds (4) of my five AP's throughout the house.

So far, the UPS units are working well with the generator - including a power out age as recently as last week.

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That’s not really an issue for me. :sunglasses:

And I do have a Tesla Powerwall + Solar system, so it’s fairly unlikely that I’ll be without power for very long.

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