Anyone who owns an EVO, or has friends or family that does, can't deny that the battery life is absolutely abysmal. That being said, there are dozens of ways to improve it's battery life without obtaining "root" permissions, however, without obtaining "root" the gains are minimal at best. So let's start there.

Root access gives you "superuser" permissions for your phone. You may not know it, but your phone manufacturer has severely handcuffed you in regards to what you can do with your phone. Making full data and application backups are not as easily achieved and, in fact, impossible if you want to make a copy of downloaded market apps without having root access.

Ok, I've danced around enough... root access gives you access to the locked data partition that resides in the ROM (I know it's confusing, but I am using the literal definition here) which is the actual partition residing on the phone itself that holds all the OS data and application data for your system apps.

You already have access to the root of your SD Card, but not to the phone, which is what you need to use some incredible applications, as well as install custom roms and custom kernels.

The Hackable HTC EVO Smartphone

To obtain root, you can check any number of sites or simply google, "rooting (your phone model)". For many phones, all you may need to do is download an app from the market called Z4 Root. To root the HTC EVO, there are several methods, but the easiest thus far has been by using an application named Unrevoked. Follow the instructions word for word and you will easily attain root for any phone.

Now that you've got root, what's the point??? Well, to begin with, as soon as you attain root, you need to verify that you have a recovery installed. For the Evo, there are but two choices, Clockwork Recovery and Amon RA. Bottom line, if you have clockwork recovery, before you do anything, get rid of it. It's absolutely terrible and has been proven NOT to perform proper cache, and dalvik cache wipes. Amon RA is bulletproof and is guaranteed to wipe anything you tell it to, without fail.

So, if you've got clockwork recovery, the easiest thing to do is download clockwork mod from the app market and install it, simply to open it, scroll to the bottom, and click on "flash alternate recovery". This will install Amon RA (and the fact that the developer packages his software with a competitor's recovery ought to tell you how much faith he has in his own recovery).

Now, before moving forward, you will need to get into your recovery and create a "nandroid" backup which is an exact image of your stock operating system. Select every possible option to backup if prompted, and do it. Once you're done, move that backup from your SD Card to your computer!!! Next, hit the xda-developer forums to find out which rom may suit you best, as well as bone up on your Android knowledge.

For the Evo, the best roms I've used (and I've personally flashed dozens) are VaelPak and GingerAle V4. Currently, there are no custom kernels for sense-based Gingerbread roms. However, for AOSP based roms (such as deck's, Cyanogenmod and VaelPak 0.2) the best kernel available is called Savaged-Zen. That being said, these kernels are where you will be able to achieve the unthinkable.

With these custom kernels, you are given the option to overclock/underclock and overvolt/undervolt your phone.

To clarify, you can make your phone run several hundred Mhz faster or slower, while using less power than the stock rom... Using an AOSP Gingerbread rom, with Savaged Zen has been responsible for a literal doubling of my battery life, but recently, there has been a flashable script developed called vipermod, which allows you to further decrease the voltage. There have been reports of users on Deck's GB rom who have gone 30 hours and had over 85% of their battery remaining.

All things considered, if you're a heavy user like myself, and you are tech-savvy, eventually you will cave, get over your apprehension about possibly bricking your phone, and make the transition. Once you do that, you will appreciate all the new options and capabilities you have available. If you are considering buying, or have already pre-ordered the Evo 3D, the odds are you'll get sick of charging your phone mid-day and end up checking out the sites I've listed. If you are in need of help, feel free to contact the XDA forums.

Good luck and happy flashing.