I must admit, my Bold was working fine until last week. I would often get over two days out of it before a charge. Then all of a sudden I couldn't get it from 7 am until 6pm without it being flat!
I am always careful to make sure nothing is running in the background so I couldn't understand it! Then I remembered the day before I had installed vodafone's sat nav (after I had discovered it's icon in my downloads section) and wondered if that was responsible.
So even though it wasn't running in the background it was the only change I had made.
So I uninstalled it, and low and behold, back to two days normal usage out of my BB.
Not sure why having it installed but not running would drain my battery, but that was the culprit.