Automatic WiFi reconnect without using too much power.

[WiPhone]

In a battery powered application, mobile, with multiple known networks (it's a mobile phone).

Currently if we are disconnected we continuously try to reconnect to the last network. Trying to connect uses more energy than maintaining a connection. This results in poor battery life when not connected.

We are preparing to upgrade this approach. Ideally we want the ability to move around between known networks or no network at all and automatically handle re-connects, but not burn through the battery doing it.

Has anyone implemented a system like this before that basically works like a modern phone? Is there a known practical approach with an ESP32?

Does anyone know the relative energy expenditure for scanning vs. just trying to reconnect to the last network?

When trying to reconnect, what's a reasonable amount of time to leave the process going? If we cut it too short I'd imagine some access points won't have time to finish connecting.

Thanks for your input!