mobile

I'm guessing a lot of people on here know this already but I recently discovered how to massively increase my Moto X's battery duration. Namely by switching off Mobile Data, I can then go a full 14 hours only dropping down to around 75% by the end. So now as soon as I get into work or any place where I'm on Wifi I switch off mobile data.

Makes me wonder why having mobile data switched on is expending so much battery power?