It's one of many things I like about the SensorPush suite of products.So, the power went off for 8 hours last night, imperiling a fridge full of groceries. The CDC says food is safe for up to 4 hours without power, but I disagree.
Does anyone wanna take bets on the quality of some pork chops? How about the Ranch dressing?
The sensors themselves (about 1.75" square and 0.75" thick) are continuously logging, for up to 30 days, and can be setup to pair with the phone app via Bluetooth, or WiFi (if you add the WiFi gateway to the setup). The sensors internal batteries last about a year in the freezers.
The phone app allows me to setup alarms with maximum and minimum temperatures and even humidity, if desired (they have various sensors available. The basic one just logs temperature and relative humidity, but they also offer sensors that can also log barometric pressure etc.).
In my case, with the WiFi gateway, as long as the gateway and router have power, and the internet works, I can receive alarms (or check all the sensors in real time) anywhere my phone can receive data, i.e. I can literally receive an alarm on my phone while traveling out of state, and see that the refrigerator temperature has been rising steadily for the past hour, and text, "Hey, someone didn't close the fridge/freezer door fully".
In a power outage, since the sensors continue logging on the internal battery, even without WiFi, I can read the logs on my phone via Bluetooth (and the alarms will sound on my phone if the sensors are within Bluetooth range), which allows me to see
1) how warm the freezers/fridge got
2) how quickly they warm up
3) for folks like me without a whole house backup genny, it allows me to prioritize cycling the power to various things, as I can see how quickly the fridge/freezers warm up, AND how quickly they cool back down when powered.