Offline Hub cannot keep accurate date time


Sorry, when I say "RTC" i mean a "real" Real Time that has battery backup. Like the one in your PC does. Your PC has a little button cell battery on the motherboard for keeping the time set when the power is disconnected.


I think there is a misunderstanding on what RTC means.
RTC is a real-time clock on the board of your computer that keeps the clock running even though the machine is turned off.

On Hubitat, there is no RTC, so hubitat gets the time on boot from the internet and software keeps counting the time. Once Hubitat turns off or reboots, that software gets stopped so nothing can count the time anymore. That’s why you need an internet connection on boot to get the current time.

The time will be correct as long as hubitat keeps running.


I stand corrected ....


Nobody said you were wrong :rofl:


My thinking was... My wife says I'm always wrong..:grin:


So, is there no bug in


Support says yes. It will be fixed in next release.


I don't know that piece. I would believe them more than me if support told you that there was a bug. Have they told you in which release the bug was squashed? if not, you could just ask them


Not that this does anything for the hub ability for keeping proper date and time, but people using a traditional UPS would be better served if they used a usb battery pack instead. For a few dollars you can keep your Hubitat hub running for days. I run a 30,000 mAh pack that keeps my hub and a Netgear LB2120 Cellular modem going for more than a day if power fails. If I was only powering the hub I could keep in going for several days.


Which one are you using? Reason I ask is most USB batteries don't charge and provide power at the same time. It might be helpful for others if you can give the brand model you are using, this way they know what to get


I have an older anker usb pack that has three usb ports and a barrel plug plug for 12v. They don't make that one anymore but I assume they have other models. Yes it charges while powering devices. I also have a Mobile power MP-30000. It too powers devices while charging. Then there is my large Krisdonia NJF-5X that also powers devices while charging.

I have heard people talking about usb battery packs not being able to being used while charging but I haven't ever wound up with one.


Let's just clarify a few things.

  1. The hub has an internal clock. It works without an internet connection

  2. The hub needs a source of time on bootup, so either NTP via an internet connection, or set time via browser in settings, hub info.

  3. If the hub is rebooted, it restores time based on what it was last, if internet is up and NTP is available, it will set itself correctly. Otherwise, it will need to get updated manually.

  4. If the hub loses power, it should restore time based on what it last knew the time was, this is not 100% and will most likely require an update to time (either NTP or user via update time via browser)

  5. All clocks drift, so you may need to update time manually, or NTP and other means are used when connected to the internet

So, the hub can and does work locally, offline. Just need to set the time via the browser on each reboot to be 100% and from time to time, double check time via browser on a local network.


Adding to this, one thing that people may not realize that all three of my usb packs are charging and I plug in a device I have to press and hold a button (the one that is used for the higher voltages) before the pack sends power out. Also, the device must draw a certain load or the usb charge port turns off. So charging my wireless earbuds draws so little current the power pack disconnects. Hubitat draws enough that this doesn't happen.


I agree as I have used my hub offline as a test and found the clock only drifts a few seconds a day. Not any better or worse than an average PC RTC with a battery.


I have 5 usb power packs, one of them an Anker which is a good brand. When charging a device if I plug them in, the device stops charging. This is more common with newer "power packs".


When everything is connected, how often does the hub check ntp?


All the packs I ever bought have a power out jack that can change voltages so I don't know if those type of packs are different than just a plain old usb battery pack. I think if you look for usb power packs where their chargers are 12 volts or higher you may have a better chance of getting one that works the way you want.. All of the ones I have are charged using a 19 volt wall wart. Perhaps the usb packs you are seeing aren't powerful enough to charge and power devices at the same time?


Then I wouldn't consider that a usb powerpack. A USB power pack is alsow chargeable from USB (5v).


You wanted a solution and I provided multiple. Call it whatever you want, jeez louise


I don't know the specifics, but I believe its on boot and at least once a day.