[Motorola Atrix 2] Apex:
If, after rooting or more likely the case after flashing a new rom, you often have battery reporting errors, and re-calibrating the battery along with some steps I will outline for you below will ensure that your battery is getting a full charge, and the battery reporting accuracy is right on. I run my device in performance mode all the time, and with a CPU overclock of 1.25GHz and various tweaks, I have about a day an a half to a day and a quarter of full runtime from my battery. This is with moderate to heavy usage (calls, emailing, text, gaming, web browsing, etc.) so you should have no problems getting acceptable battery performance after following these steps:

1. Take the case off your device (one of the latter steps involves taking the battery out from the phone while it's plugged in. Make sure your case won't stand in the way.)

2. Install Battery Calibration app from the market

3. Plug in your device to charge while it's on, wait till it gets to a 100%

4. When the charge is 100%, open the BatteryCalibration app and lookup what the charge is in MV while at 100%. Write it down.

My Atrix 2 was showing ~3400MV while at 100%, which is definitely not the maximum capacity.

5. Discharge your device completely until it shuts off.

A good way of doing this quickly is by turning on wifi, and a video player.

6. Without turning on the phone plug it into a wall charger and let it get to 100%

7. When it's at 100%, without unplugging it from the wall charger, take off the battery cover, and take the battery out.

Your phone will "reboot" and show a Missing Battery icon.

8. Without unplugging the phone from the wall charger or turning it on, put the battery back in and wait until the phone recognizes the battery.

9. Your battery should now be recognized by the phone, and showing a charge % significantly lower than 100%.

Mine showed only 5%.

10. Let it sit there charging for 2-3 hours (or more).

My phone wouldn't charge past 10%, but yours might. The numbers don't matter much as the phone is definitely getting additional charge that could have been lost while flashing ROMs, etc.

11. After 2-3 hours (or more), turn the phone on while holding the volume down button and get into CWM.

Do not disconnect it from the charger still!

12. Wipe battery stats in CWM, reboot.

Do not disconnect it from the charger still!

13. When the phone turns on, go into Battery Calibration app again and look up your MV numbers -if you were like me, they should be significantly higher than before. After this whole process I had 4351MV at 100%, comparing to 3400MV before calibration.

Do not disconnect it from the charger still!

14. Before going to sleep - Install Watchdog Task Manager Lite from the market. Go into it's preferences, set CPU threshhold to 20%, check "Include phone processes", check "Monitor phone processes", check "Display all phone processes", set system CPU threshhold to 20% as well.

Do not disconnect it from the charger still!

15. Make sure your wifi and data connections are off. Now finally unplug the phone from the charger.

Go to bed, let your phone sleep too.

16. Success! Next morning check where your battery % is at and if you followed the instructions correctly / got lucky like me, your battery life should be 90% or more.

I went to bed with 98% and woke up to 94%. So, I consider this mission a success.