The Ruuvi is a complete beast. It'll last for years on a single coin battery. I got them from the initial Kickstarter and replaced batteries last year.
You _can_ read them with just a cell phone or hack a Raspberry Pi as a BLE listener, and It'll work just fine most of the time. Even ESP32 has a system for reading the tags with esphome I think.
The antenna on that thing is completely ridiculous. My Raspberry Pi had to hang from the ceiling to get even 10% of the readings from my sauna (lined with foil to keep the heat and moisture in as per Finnish building code).
I got a the Gateway, quickly powered it up at my desk and boom, it found the sauna tag immediately, zero packet loss.
I've got one in both my fridges and freezer, zero issues. Sauna goes up to 80C normally and is MOIST, no problems. People even float them in pools, just cover the moisture sensor hole with tape and double bag it in ziploc.
You can get similar BT devices from china, but they eat up batteries like candy and the signal strength isn't that good.
You _can_ read them with just a cell phone or hack a Raspberry Pi as a BLE listener, and It'll work just fine most of the time. Even ESP32 has a system for reading the tags with esphome I think.
But for the best results I recommend getting their official Gateway: https://ruuvi.com/gateway/
The antenna on that thing is completely ridiculous. My Raspberry Pi had to hang from the ceiling to get even 10% of the readings from my sauna (lined with foil to keep the heat and moisture in as per Finnish building code).
I got a the Gateway, quickly powered it up at my desk and boom, it found the sauna tag immediately, zero packet loss.
I've got one in both my fridges and freezer, zero issues. Sauna goes up to 80C normally and is MOIST, no problems. People even float them in pools, just cover the moisture sensor hole with tape and double bag it in ziploc.
You can get similar BT devices from china, but they eat up batteries like candy and the signal strength isn't that good.