I'm not sure where the best place for this is... It applies to smartphones in general, but I ask it because of a problem I'm having on my Galaxy S3. Does keeping mobile data on (when connected to/using wifi) waste battery power? I have AT&T and I updated my Galaxy S3 to Jelly Bean last night. It seems that in the AT&T Jelly Bean update people, such as myself, are losing the mobile data toggle in the notification panel. In the past, I have toggled my mobile data off when I turn the wifi on, and vice versa, to save battery. Both of the toggles were right there and there's no reason to have both on at the same time. But now that turning mobile data off requires a maze of menus I'll have to change that habit... I figure the easiest fix would be to simply leave mobile data on all the time. Just toggle wifi on/off when I need it. I did some research and it sounds like mobile data only uses up your battery when it's being used (that it doesn't waste battery just by being on- compared to wifi, which uses up battery searching for networks even when it's not being used). So I can turn on my wifi when a network is available and I won't be wasting power having the mobile data on. And when I leave that network, I just turn wifi off and carry on. Unfortunately, I can't find a solid answer to the question. If it does waste battery by being on then I'll have to find an app that automates things, or perhaps a toggle widget. I know there's plenty out there. But I'd prefer to avoid that. Thanks!