Just wondering how these would impact the battery life? Ideally I'd like Wifi to be on all the time so that it automatically switches to my known networks (home/work etc.) when I get there. And equally, I'd like bluetooth on all the time so that it connects with my car handsfree when I set off, automatically. Would leaving these both on constantly seriously degrade the battery life though (bluetooth won't actually be active most of the time, just on so it's discoverable)?