I finally found out why my battery only lasted 12 hours and some times less..

My cell provider dosen't have full 3g coverage, wich meant my phone switched alot between 2.5 and 3g/3.5.

So i took the step of switching from double network to only gsm. This keeps my phone on the 2.5 network all the time. And keeps my phone from searching for 3g everytime it switched over to 2.5.

Now i can have half a battery left once i go to bed at night, where it used to atleast be completly drained.

Another weird thing this fixed for me is that its more reliable at finding webpages when surfing the web.