I had similar problems with my battery after upgrading to JB. I cleared the Cache partition and that seems to have cleared up the battery useage . It's a lot better than ICS now .
I'm not on the newest JB, I'm still on the X-Mas leak. But since then, I've noticed a major decrease in battery life on my Maxx. I've seen people say their battery is better, some say it's worse. I guess I'm one of the unlucky ones.
Something I also noticed, if anybody has an explanation- I stopped using the stock homescreen. I'm currently using GO Launcher and this has increased my battery life significantly. An average day I would probably get 8 hours of moderate use on the stock homescreen. I changed to GO Launcher and noticed I can roughly pull 16 hours now with the same moderate use. Anybody know why? (No widgets were used on both)
I too did a cache partition wipe last night as my nemesis is system wakelock keeping the phone awake almost all the time. That dropped to 3 percent today which is way way down from the last two days. Battery is almost back to normal now...at 70% with 16 hours and 11 minutes on it. That included a 40 minute phone call and almost 2.5 hours of screen time. I switch to 3G at work as there is marginal 4G in the old building I work in and no wifi at all.