I just bought a dell inspiron 5537 (which already comes with ubuntu 12) and I removed the ubuntu and installed Ubuntu 14.04 alongside a windows 8.1.
After struggling with the system is running low on graphics error I got it fixed by installing AMD Radeon HD driver. However I noticed that before (when I had the Ubuntu 12 that came with the device) the battery life was up to 6 hours and now it's no longer than 4 hours. So now I think I should disable the AMD card (since the built-in intel HD card will work fine on Ubuntu), maybe that will extend the battery's life?
But, is there a trusted way to do that without returning to the low graphic mode?