I was researching a way to have to have a kind of “universal” Arduino node sensor.
When I say universal, I’m talking about connecting to it several sensors type (Temperature, Humidity, Lux, … such as LDR, NTC, PTC, DHT11, DHT22, DS18B20, I2C sensors). I found a lot on the net, some very interesting and fine products such as Moteino, Anarduino miniwireless, Jeenode, but as today, none are especially made for ultra low power with long battery life when using classic battery such as one AAA, CR2450 or CR2032 Cell Coin. So not using Lipo, or any rechargeable batteries.
It can use only one AAA or AA battery and run for years with specific Hardware and software design, it can also run with old batteries until 0.6V
You can read all informations about this project on my blog here