Does disabling mobile data when I'm connected to wi-fi conserve battery? I always do this out of habit, but it recently occurred to me that Android might be clever enough to automatically turn it off when I've got wi-fi access. Is it?
Connecting to WiFi automatically disables mobile data on most phones, so turning it off manually does not save your battery. There are some phones which have a "turbo download" mode, that uses both WiFi and data to download files faster, however most phones don't have it.