Replace your Moto Razr Battery with a Moto Razr MAXX Battery
The most significant difference between the Motorola Droid Razr and it’s brother, the MAXX, is the MAXX’s larger battery. Now, those with the original Droid Razr can have that extra battery life if they desire. XDA Senior Member Wardo5757 has successfully taken the battery and battery door from the Droid Razr MAXX and implanted it into the regular Droid Razr, resulting in longer battery life for the original Razr.
The method does have its dangers, though, and anyone who attempts it should be extra careful in doing their homework before attempting as this could cause serious damage to the phone, battery door, and battery. The door is not easy to open and the battery is sealed in, but both are removable if you’re careful and daring. From there, it’s just putting the battery and door from the MAXX onto the original Razr and reaping the benefits. The one downside is that there is a small gap in the SIM card door and the battery cover which, which will affect the Razr’s resistance to water and dust.
More information, screen shots, and discussion can be found in the original thread.