[Xperia Arc General] jhnjrdan:
Well, it worked with three other testers, some friends of mine that found the same problem. If you're facing this, try and feedback me. Just want to make sure that I've helped someone.

This guide is for those who have the 0% battery issue, found the fix by Bazoocaze (thanks a lot !!!) and are experiencing some quick battery drain. If you're not, then you can go read something else :p In two or three weeks of testing, I believe that this does not have something related to the ROM that we're using. The processes on background and the use of CPU is relative, but maybe a process is using too much energy, and if we keep the energy level on a low status, I think this process won't have so much energy to use. And maybe the kernel, or the kernel's governors are affecting something, not sure of this last one. I've also concluded that this don't have anything to do with the Wi-Fi modules, because I've already tried that fix, and it drains pretty quick anyway, some believe that there is a bug affecting the Wi-Fi, and it doesn't turn off, even if we turn it off on the menu.

First of all, if you haven't find the fix, read this: http://xdaforums.com/showthread.php?t=1312398

You can also use the DooMKerneL ICS v4 that DooMLorD developed, and it already has the patch built-in (I recommend for this guide): http://xdaforums.com/showthread.php?t=1520654

1 - Flash the kernel, the one of Bazoocaze or the DooM Kernel

2 - Turn on your phone, normally, make all your configs, and do a little test, BEFORE following this guide. See how many time your battery can hold on. If you feel that it's going out too fast, keep going on the guide.

3 - For this operation, I suggest you buy or download the free version of SETCPU, never forget that name. NoFrills didn't work very well to me..

4 - Overclock, if you want and if you're using DooMKerneL. Keep the MHz min on 364 (will explain later)

5 - Go to the profiles tab and press the ''plus'' button. Change the MHz max to 768 and keep the min at 364. In profile, select Screen Off, and change the governor to powersave or smartass and set priority to 100%

6 - Save it, and press Enable and Notifications on the bottom of the screen.

7 - Now test it for some time. Try not to keep your screen always on, as it ''cancel'' the effect of this guide.

Explanations:

a) The reason to keep the min MHz at 364 is that you won't face stuttering in the screen on/off, because the app will only change the max value, and not the min value, which makes the system still work fine (I believe, if some dev could correct me..). It behave better in AOSP alike roms.

b) NoFrills didn't give me the same results as SetCPU, that's why I'm recommending SetCPU. Make some effort to buy the Pro app.

c) The main trick is to reduce the power usage and capacity when the screen is off, because you don't use your phone 100% of the day, and because the process that may exist (mentioned above) would not use the whole capacity of the energy and the CPU as well. That's why it works. At least worked for me.

d) There is absolutely no hardware of software issue if you try this guide, you can uninstall the SetCPU app and use kernel other than DooM's. It's safe and quick, if it doesn't work, you can always revert everything.

Please, if you want to try this guide, give me the feedback. As I've said, I just want to confirm that theory and make sure that I've helped someone.

Thanks Bazoocaze and DooMLorD for being life savers!!!!!!!!

Bye :D