Yeh that's weird, I was shocked not just at the incredible standby time, but also in use batt life. Only change I made was deleting Apex from the Rom and sticking with Go LauncherEX as don't really care for Apex. Def a slick Rom. I'm on 2.2.2 still, haven't updated to 3.4 or whatever it is now lol. Screen is kept on auto too.I'm actually on Shostock2 also. The standby time is fine for me on the GSII with that ROM, but it's when I start actually using the phone that it seems to drop like a stone. I typically keep my screen brightness around 50%, but last night I lowered it a little to see if that makes a big difference (since I know the screen can eat up the battery if set too bright).
The best ROM I've ever used, battery-wise, was UnNamed 1.5.1. I couldn't kill that thing, no matter what I was doing. But in that version, the creator removed noise suppression from the mic, and I was getting all sorts of complaints from others that when I was on the phone with them, the background noise was awful. He put it back in in later versions, but I never could duplicate the battery life 1.5.1 had.
I absolutely love Shostock2, though, as far as look and use goes. The only thing I wish the creator would include is the Jkay mod, as I like to be able to remove the battery indicator number from the status bar (otherwise, I feel like I obsess over that number...LOL).
Maybe I should do a wipe and reflash and the battery may get better. I also haven't checked to see if there are any updates lately. Right now I'm running 2.2.6.
I used battery calibration after too to get accurate readings, as 1st day was great, then 2nd day was odd as it didn't last as long, but ever since calibrating it has been excellent.