Originally Posted by furious duck
Up until 3 weeks ago I worked in an office where I could only get a 2G signal and found my battery drained very quickly. I had to set the network mode to "GSM only" otherwise I'd be out of battery before I got home. It looks like the phone uses the juice trying to find a 3G signal. No problems since moving though. I don't use mine excessively and have done all the battery optimising tasks (reducing syncing etc) but I'm usually down to 25% - 40% at the end of the day. So not fantastic but I've been charging my phones overnight for years now so it's fine for me. No idea how people are making there's last 3 days though!
Yep, when on auto (2G/3G) it actually 'prefers' a 3G connection so will always (constantly) try to switch to it, thus using battery... Only solution as you realised was to set it to 2G only...
Surely it would be better for handsets 'auto' mode to be strongest signal preferred?! Why have 1 bar of 3G when you can full bars of 2G?!