- Fri Apr 28, 2023 3:17 am
I don’t want to bore you but just so you have a very high level understanding of what I have.
I have 6 temperature sensors. A mixture of hard wired, Bluetooth, and zigbee. They all are monitored by a home assistant instance which does run on a Raspberry pi. All are double battery backup, whole home generator. There is a smart switch which is plugged into another smart switch. The first one is main power. The second is power to the freezer compressor. I won’t even get into the light situation, which is itself in another smart switch.
The mistake I made had everything to do with the built in thermostat on the freezer, which I didn’t modify from the start. Which means when power was continuously applied, it did what it’s designed to do. Freeze.
So, long story short, the 6 temperature sensors are averaged. Home assistant creates a virtual thermostat. When sun comes up, it’s target is set to 75F and it basically commands the smart switch to the compressor to turn on, which cools the freezer to 75, as needed, and then when it gets to 80, it kicks back on, etc… when sunset happens, the target is 55 and it cools to that, then stops, etc…
What happened was some some my esp32 controllers that talk to the Bluetooth thermometers hung up, and was reporting the (incorrect) warm 72 temp to the home assistant. So when the device was calculating the average, it was skewed by these “stuck” temperatures. The temp was actually in the 50s but the controller thought it was hotter, and kept cooling. Until below freezing. I have a rule that says when the average temp goes below 45 for more than 2 minutes, cut power to the whole thing (via that first smart switch).
My logic was flawed because that rule was based on the mean temp, which was skewed. The skewing wouldn’t happen if the Bluetooth battery dies and the unit doesn’t report back. But because the esp32 controller kept sending the wrong high temp, it failed.
So now I have these rules to monitor each of the thermometers and if any of them get below 45F it will kill the power for an hour and then start up again.
In addition I modified the built in thermostat in the freezer so the coldest it chilled was 40F even if let it run all night. In the end I will replace this with a wine cooler thermostat so the unit will not get below 50.
So hope that helps you all understand why I’m not going with any alarms or other additional things. The system I have sends me text messages to the phone and Apple Watch, so I can be away and know. I can also manually kill any power to anything remotely….from anywhere.
It was just a simple logic mistake that cause me to lose my favorite Nepenthes. It’s only money, and time. I hope one day to get another of these ones I lost. In the near future, I will just keep hoping that something survived… I’ll keep the forum updated if they do.