[luv-main] Disabling wifi on laptop

Hi, I've recently purchased a Dell vostro 3350 laptop, and to save battery, I was planning to disable wifi, when it wasn't required. On my old laptop I could use the rfkill package like so: rfkill block wifi But it seems to have no effect on my Dell. The wifi hot key on the laptop does not seem to work either (from the console). Does anyone have any other ideas? If I do ifdown eth1 to bring down wifi, is it likely the wifi will still be consuming significant battery? Thanks for any help, Dan