Why did my battery usage on 3G grow with the Android 2.3 update? There were different nice features followed by the official update of Xperia X10 to Android 2.3 like the sound stuttering, but the most annoying is the following. 

I live in the Netherlands and here it's nice to use 3g a lot to have internet connection whenever you need it. Both on 1.6 and 2.1 I never run into the problems with battery using 3g. Moreover, there were problems rather with WiFi which ate battery a lot. 

Unfortunately after I've updated the phone, things have changed. WiFi  is working fine now though it seems to me that it's off when the display is off: it establishes connection for about 10 sec each time I turn on display. But when I turn on 3g for the night, on the morning the phone is out of charge.

I don't think it's about apps using 3g, since:


if these apps need the internet connection, they will use WiFi as well, but if I leave my phone with WiFi for the whole night, only about 2-5% of the battery are lost for the whole night long.
in settings-&gt;applications-&gt;battery usage I can see that Cell Standby = 35% while apps in total are about 6%.


That gives an idea that 3g connection is rather expansive for my battery - but I don't have an idea why did it happen after an update on v. 2.3. 

I've never rooted the phone, so all updates were made in the right way. Hope someone can help me.
"cell standby" = "background sync". And if your Wifi turns off on screen off, apps will use 3G instead.

You might want to check your Wifi policy, which is hidden in the "advanced" menu: When in "network &amp; wireless" -> "wifi", hit the menu button and select "advanced". Here, switch your Wifi policy to "always on" -- so it will stay on when the display is switched off, which means no 3G fallback as long as Wifi is available.

I've read about this issue a couple of times, and many report setting the Wifi standby policy as described above largely improves the situation.



UPDATE:

I obviously wrote bullshit here. I left the bullshit in (but striked it so you can see where I was wrong). Closer investigation brought me to this: What is Cell standby and how can I keep it from eating my battery?.

So basically my reasoning here was wrong, but luckily the recommendations still match somehow :)