[Samsung Epic 4G Touch] I_FLY_Z3R0:
First of all, I would like to thank all of the amazing developers who make this phone as awesome as it is.

Once again, THANKS!

*Please do not blame me for anything that happens to your phone*

I know there's a lot of people out there who say they get great battery life, but how do they do it? Well here's what I do. I'll try to be as specific as possible. I get around 15 hours of battery life every day with around 50% left when I plug it in when I go to sleep. This is with around 3+ hours of screen time. This includes a lot of facebook, texting, e-mail, whatsapp, and other applications.

I am currently running Blazer ROM 4.1, but all of these ideas will also work on Calks 2.9. Any other ROMs most of these will work but ask before trying if you're not sure! Also, I'm running gunslinger kernel. A very smooth kernel that is good for everyday use.

Personally I think that Blazer gets better battery life overall,
but while sleeping, calks decreases at a slower rate.

First, I'm running Blazer ROM 4.1 with the FB21 FD10 FE07 Modem. I've used other modems like EL29 and EL13. So far the FB21 and EL29 have given about the same battery life, but the FB21 FC07 FE07 has better speeds. For more information on modems go here.

[url]http://xdaforums.com/showthread.php?t=1352310[/url]

Next, I underclock and undervolt the CPU. If running Blazer ROM, I recommend setCPU to underclock it which can be downloaded in the market. The max CPU speed is set at 500MHz and the min at 200MHz with the scaling set on ondemand. For Calks rom, you can also use setCPU or use the built in battery script to underclock. This can be found using a text editor in /system/etc/int.d. Also, I flashed the calks undervolt -100mV which can be flashed through CWM and found in the link below. (The -100mV zip can be used with both Blazer and Calks.) With this configuration there is absolutely no lag. Even though these speeds may seem low, the phone is still fast!

[url]http://xdaforums.com/showthread.php?t=1332837[/url].

Another thing that possibly saves the most battery is an app called Juice Defender. The purpose of this app is to turn off the data when not in use. There is the free version available but I use the ultimate version. In the settings I set it to aggressive. I am in a lot of areas with low signal (College classrooms) and this really conserves battery when I'm not using my phone. You can also configure apps to leave the data on. Definitely consider this app if you're in areas with low signal!

[url]https://play.google.com/store/apps/details?id=com.latedroid.juicedefender&feature=search_result#?t=W251bGwsMSwyLDEsImNvbS5sYXRlZHJvaWQuanVpY2VkZWZlbmRlciJd[/url]

Some more things to consider are your display and background data. I ALWAYS keep background data off except for when I'm browsing the market. This can be found in Settings>accounts and sync. As for the display, auto-brightness is always on. Other than that, nothing has been changed with the display. Also, I keep GPS on about 99% of the time and rarely use bluetooth.

If you notice your battery draining real fast while it should be sleeping, try downloading better battery stats. It will show you which apps are using the most battery on your device.

Please feel free to add your own suggestions/pictures of your battery life or ask questions. For a more personalized response, send me a personal message and I'll try to get back to you as soon as possible. I'll update this with new ideas as I find them!

Good luck to everyone with this! Hope I helped some people. Hit that thanks button if I did!