I have had really good luck with using Ecowitt weather sensors for this. I have one in every fridge, every freezer, the shed, attic, etc etc. They are cheap, accurate enough, reliable, and use AA batteries. They will also integrate with Hubitat without needing to talk to their own cloud. But, they DO need a LAN to report to the hub.
Another vote for Ecowitt. Cheap, far more reliable than z-wave or zigbee for me, and with a local wifi connection integrates beautifully (locally, with NO cloud dependence) with Hubitiat via @sburke781 driver. The "base"unit draws only about 1 watt and also gives you local temp and humidity on its own. And if for some reason the Hubitat hub goes down, the Ecowitt device can also connect via cloud to an Ecowitt app so you can still monitor the device - you're just not dependent on that cloud connection.
Even a mobile hotspot can handle the wifi/routing. In fact, I currently have an Ecowitt weather system running at an off grid property under construction (no electricity at all on site). Routing is via a Verizon home internet box, and all of it runs for a couple of days on an old marine/RV battery I had laying around.
This thread motivated me to look and see if Centralite Zigbee Temperature/Humidity sensors are still available. Centralite was the OEM for most early SmartThings sensors, as well as for the Lowes Iris v2 sensors. My house is full of these Iris v2 Zigbee devices, which have been extremely reliable and have excellent battery life using CR2 batteries.
Ezlo bought Centralite, and appears to still be manufacturing very similar devices to the old Iris v2 sensors. I have never used their Temperature/Humidity sensors, but do see that you can buy 3 for the price of 2 on Amazon right now. That brings the price down to ~$12 a piece, which is pretty inexpensive. I just placed an order to try them out, as I'd like to see how well they work in my two refrigerators to make sure we don't lose a bunch of food should a failure occur.
What are you using for the network in the RV? Is the RV parked at 1 site for the season or do you travel with it? If using the local Wi-Fi at the site, I always worry if the whole site power goes out I would not get notified.
I have gone with Waggle to monitor power and temperatures when I travel with the pets. It uses the cellular network and has a built-in battery, also if it doesn't check in periodically, I get notified of the network failures.
I think it is worth the 250 dollars a year subscription.
I have found very few site WiFi signals are worth anything so we don't rely on them
We are not full timers but do travel quite a bit and since I work remotely, we do need internet, so we have T-Mobile and Verizon data plans, generally 1 or the other will work.
We have a Pepwave Cellular / WiFi router which runs on 12v so we have battery backup, works pretty well having multiple carriers
Good find, please let us know how they work in the fridge.
(I forgot to mention, another thing that I like about the Ecowitt sensors is that if you choose to use their cloud too, you get good graphs for free, whereas historical data on Hubitat is another project.)
I have one ST branded one in my attic for 8-9 years and it’s worked great. Bought a few more many years back for another attic and crawl space. Batteries last a long time.
I don’t have the temp humidity sensor in my fridge but I do have a Centralite contact sensor in there, same looking device. It has been working well for 5 or so years. Batteries last over a year.
