[Samsung Epic 4G Touch] steddora:
I hear it all the time... Does this rom provide good battery life? How's the battery life? Why is my battery life suck? So; it may have been done already somewhere; but I figured after watching and logging my own battery life, I could really help some others. I'll section this out; no specific order at all.

ROM: No matter how many times I look at a ROMs thread, I get to see a multitude of "How is the battery life" posts. You know it, I know it, and we all know it. Truth is; after using plenty of ICS roms out there; most of them have similar battery life. Currently I'm running the Blu Kuban rom, and I get just as good battery life as I do with most other touchwiz based roms. To each rom their own. Read up on the rom itself before you go blaming the rom for battery life. I've noticed the JB builds aren't the best with the battery, but we must remember those are usually noted for having bad battery life. Either way, most of the ROMs I've used personally perform rather similar in actual battery life.

Kernel/Governor tweaks: I can't stress this enough. Governor's and Kernel Thread. That thread will teach you more than anything you want to know about kernel and governor tweaks. Some of these governors can send your phone to absolute battery immolation, while others can set your phone up to last 2x as long. I prefer the more conservative approach and end up with a ton of battery left at the end of the day. While these settings are important, the most important is yet to come.

APPS. I can't stress this enough. I used a quite a few different setups to find what all really uses battery, what doesn't, and what I should to to maximize my own battery. For those of you who don't know me at all, I work ten hours a day, and I used this time frame to measure the battery usage while it's sitting in my car for ten hours. I have a Trexcell 3800mAh battery, so it's roughly 2x the power as the stock battery.

What's the number one usage on my device? NOTIFICATIONS! All of those apps that automatically feed their greed by getting updates from the servers or whatever. Facebook, Hotmail, Tapatalk, and EVEN just the gMail app could drain 10% of my battery in ten hours. Let me show you my findings.. These are the normal apps I use that can automatically update over certain time frames.

Hotmail

Tapatalk (Xparent Red version)

gMail

Facebook

Now if they all automatically update on the stock settings, ten hours of work will mean I'm coming back to a phone with only 75% battery. With only 4-6 hours of deep sleep! That means these apps are waking my phone up to do whatever they want for quite a while. With all of them set to be manually updated; I come to 95-97% battery life. That's quite a stretch in a difference you know?

So, I tested each with the others off and here is what I found. (I tested for three days, wrote my results for each day, then switched to a different app)

Hotmail set to update hourly would leave me with about 90% of the battery at 4:30. Average deep sleep times were in the 8-9 hour ranges.

Tapatalk was setup stock for 15 minute updates. I'd lose at least 10% on the battery every day! Deep sleep however would range in the 8.5-9.5 hour range.

gMail was set to update hourly and would leave me with 95% each day with only keeping the phone awake for 30 minutes on average.

Facebook updates are odd; since they don't happen all the time. So I had a good friend post on my wall three times a day and noticed that it would eat a LOT of battery, usually 10-15% and keep my phone awake for about 30 minutes a pop.

Now I must note, for my tests I had almost nothing installed on the phone aside from the apps listed and the basic apps available in the blue Kuban rom. For the tests, I set google voice to do not disturb so phone calls and the like wouldn't be an issue.

With all four of the apps set to default updates however (no messages on facebook aside from one day), the battery life ranged from one day being 67%, second day ended with 74% and the third day left me with 72%. That's a LOT of battery for just sitting in my car.

After these findings, I've switched all my apps to update only when I manually refresh them, and I'll tell you what, my battery life has never been greater. I literally come home with 95% battery on average and can sit and play on my phone almost all night without charging until it's nightly stay on the charger.

Just some other tips I've learned along the way.

Wifi is a battery slaughterer if it's not connected. Driving around the city and having the wifi detect all kinds of networks is just battery slaughter. So, my rule of thumb now is, when I leave the house the wifi goes off. It's true that wifi uses less battery than 3g and 4g, but when you're picking up random networks and the radio is searching through them, it's just no good for the battery.

Brightness, it's a key. I can't stress this enough, if you don't need 100% brightness and want better battery life, turn that screen brightness down to an acceptable level.

As an ending to this short but sweet little tidbit of information, I'd like to share why I wrote this, did all this testing, and why it mattered to me since I have an extended battery. My phone is my link to the world, my family, potential jobs, and just my favorite handheld entertainment device. Me and my fiancee` both have the E4GT, and I have the extended battery. She has the stock battery and it doesn't last long at all for her. So my plan now is to work with her on her battery life, and give her this extended battery. I won't need it since I literally have to try to get to 50% battery life with it. I usually end up plugging my phone in for the night at 65-75% battery. I just figured I'd share this with people on the forum as maybe a different approach to saving some precious battery. If you like it, tap the thanks button. If you have any ideas to better this, let me know!