Maybe if you don't use it. I'm lucky to get 24 hours out of mine (I've done the battery setup stuff and on jj9). That's with either wifi or 3g on at all time, but gps off, though my reception at work is poor. My old 2g work bb lasts 4-5 days.
CM7 roms struggle to get me through the day, but SS5 does 2 days at a push, I do charge it nightly though.