How to configure ESP8266 to connect to different password protected networks | ESP8266 Wi-Fi Module | Forum

I would work with the wifi examples and use the "scan" function and the "deepsleep" function to look around say each 30 seconds or so because battery use will be a big factor .I use a remote control airplane battery on mine .
(5000 mAh 7.4... 2 in series LiPo and use the charging port to get about 3.6V and that can be used directly or through a diode to further reduce it )

You would need a screen I suppose to see whats happening but it will just register any network it sees . You can't connect unless you have the password and you will need some way to enter a password?

If there are only say 10 known wifi's you will connect to then you could code an if..then statement to try each one and join the one found.

Then its a matter of what you want to do there
Known passwords could be stored on the chip and applied as needed.
You don't need the Arduino board specificallyl as the ESP8266 has 5 times as much memory capacity and works 5 times faster than a ATMega328P