maniacbug:
Running ATMEGA328P-PU, which is pico power, right?
From the datasheet...
Speed Grade:
– 0 - 4 MHz@1.8 - 5.5V, 0 - 10 MHz@2.7 - 5.5.V, 0 - 20 MHz @ 4.5 - 5.5V
Yup. Bear in mind that the maximum recommended processor speed at that voltage (2*1.2=2.4V) is <= 4 MHz. I haven't had any problems running ATtiny85V processors (similar specifications) at 8 MHz / just over 1.6 volts.
For one, an nRF24L01 radio. It's rated for 1.9-3.6. So I guess if I went with straight batteries, I could stack 3 as far as that guy is concerned.
1.2 * 3 = 3.6. That gets you nicely into the 10 MHz band allowing you to reliably run the processor at 8 MHz. If you can, running the processor at 1 MHz will significantly increase the battery life.
For temp, I had been looking at MCP9700 which can go down only 2.3V.
I can't provide any help regarding sensors.