[RAZR HD Q&A, Help & Troubleshooting] iBolski:
Battery life appears worse because it's more than likely poorly written apps. The API for KK had improvements made, and apps that were written before KK may have worked fine under JB, but were still poorly written but could get away with it. Once KK came out, the poorly written code was finally exposed for what it is: code that should be fixed.

Depending on how the apps are releasing resources, it could cause drain on the battery.

I myself have found my battery life to be the same as it was under JB.

One thing to really look at it is your battery stats to see if there is something waking up your phone while it's asleep. Go to Settings->Battery. Select the graph and then look at the lines below it (see attached jpg for an example).

In the screenshot attachment I've provided, compare the "Wake" line with the "Screen on" line. What you really want to see is that when the screen was off (no blue lines in the "Screen on" area), you should hopefully see minimal blue lines in in the "Awake" line in the same positions. If not, it means something is waking up your phone. In the screenshot above. you can see that there are definitely some times where my phone woke up while the screen was off. WiFi was on all the time as well. Of course, you'll probably still see some lines if you have syncing turned on, or other background processes. You might never be able to completely ensure there are no lines when the screen is not on, but you want to minimize them as best as possible. In the picture above, I was having my phone do other things (update apps, etc), but usually, I can get it minimized pretty well.

To better help determine what might be causing this issue, you can download an app from Playstore called "Wakelock Detector". Basically, charge your phone up completely, install Wakelock Detector and allow your phone to sit for about two hours without being charged and then run Wakelock Detector and see what it says. You might find you either have a lot of syncing going on (I've turned a lot of that off including gmail sync, photo sync, play books, play magazines, play movies/tvs, soundsearch, etc). Syncing is usually the #1 culprit for most people after setting up their Google accounts because they just go with whatever was set up. Or, you might find an app that seems to stay on a lot and will warrant more investigation, but it could definitely help in determining what the issue is.

I also am rooted (which does NOT affect battery life) and I run the Xposed framework with the Greenify module which helps. With this, you can "Greenify" apps - in otherwords, prevent them from causing a wakelock. Many games these days will just wakeup to give you notifications. In many, you can just go to the App Info for the app and uncheck the "Notifications" checkbox. Greenify is different from task killers. It doesn't "kill" the task (which can cause even MORE battery drain), but instead, prevents it from "waking up". The donate version allows you greenify system apps as well, but that could cause more issues. Usually, greenifying user installed apps is usually sufficient. So, if you have a misbehaving app, you can use Greenify to discipline it until it gets fixed (if ever). Or, remove the app and see if you can find a replacement.

Also, having GPS on all the time drains. Most of the time, you can either live with the battery saving mode or turn it off altogether until you need it.

On my Razr HD (non-Maxx), I can get about 72 hours before I'm down to under 10%. This is on stock or CM11.