[AT&T Samsung Galaxy S II SGH-I777] VanillaCracker:
OK here is the official SGS2 I777 Battery saving thread. I don't mean to be a culprit and post "another battery saving thread", but I am. So get over it. This thread is meant to maintain the battery savings threads, all in one place. INCLUDING: Battery savings tips, philosophies, and other methods of efficiently managing the charge that your battery witholds. Since I searched through basically all of the 17 pages in both the I777 and regular SG2 to collect all this. NOTE: THIS THREAD IS NOT MEANT TO ADDRESS BATTERY DRAIN PROBLEMS OR ANYTHING OF THE LIKE. DO NOT POST YOUR PROBLEMS HERE. This is simply a collection of what I found to be the most essential threads and information regarding efficient use of battery charge and battery savings. I'll update this every few months, or as I see fit. I don't see things changing much since the way a battery works, and our android os will be relatively similar over the years.

I realize that people looking for this information could just go through all the threads like any other xda troll would be the first to point out, but I also recognize the noob community for this phone (I was once there myself) and would like to be helpful in providing it all in one place to prevent others from wasting their time, whether deserving or not :p

BATTERY SAVING THREADS:

*Basically what I did here is I just weeded out all the crap and gave you the threads that are actually of use*

Here is your basic, comprehensive Battery Saving thread:

http://xdaforums.com/showthread.php?t=1234264

(It contains many simple changes that are obvious to some, including lower brightness, turning off animations, and then more complex changes such as under volting and fast dormancy)

More general tips plus freezing apps and undervolting:

http://xdaforums.com/showthread.php?t=1335864&highlight=battery

More general tips: http://xdaforums.com/showthread.php?t=1443603&highlight=battery+life

THE TWO THINGS THAT KILL YOUR BATTERY THE MOST:

Super AMOLED Screen: Now it's all apparent to us at this point that android screens (S-amoled's) kill very large amounts of battery. You will save copious amounts of battery if you do not use your screen as much, hence why half of the people posting their battery stats have screen on like once an hour for half a second. They basically don't use their phones.

Data/Radio: Ever notice that when you put your phone on airplane mode before you go to bed, when you wake up it's only gone down by about 1%? That's because you're not getting any service, and have no data coming in. Believe it or not, the phones hardware is pretty efficient. CPU's don't use very much idle power at all, and I expect that to stay the same, even with quad-core processors coming out. It's mostly the over air things (and screen :() that kill our battery. Data itself uses a **** ton of battery. On a daily basis (And I've tried just about all the roms; CM7,CM9, MIUI (GB and ICS), SammyTW ones, etc.) I use a considerable amount of data. I try to have my data on most of the day since I get facebook notifiations and send/receive MMS's, but on the days where I have it off for a couple hours I start to notice, damn, my battery is still pretty high :D

EDIT: Using Edge/2G saves a lot of battery if you're someone who needs data on most of the day. I recently switched to instead of intermitedly turning data on and off, just having Edge on all day (for notifications) and then switching to 3G when I needed to browse or use maps, etc. Idle usage of Edge vs. 3G is probably around 40% less battery consumption (my opinion), it works really well for me.

PHILOSOPHIES:

If you want to compare your own battery life with others to get a better idea about things, check out this thread:

http://xdaforums.com/showthread.php?t=1498303&highlight=undervolt

Juice Defender + others: I am a fan of this application. I used to use it for the first couple months I had the phone and it made a significant difference (mostly because of data deactivation). It makes 20-35% difference in savings from having not micro-managed anything yourself to then using the app. There are other variations of JD, GreenPower, Battery Booster, etc.

If you want more information about Undervolting, or the process, please check out:

http://checkrom.com/threads/more-ba...ry-before-posting-about-bad-battery-life.542/

Fast Dormancy effects the trafficway in which your data makes it to your phone, both effecting the speed at which is arrives, and the battery it consumes while doing so. Check out this thread:

http://xdaforums.com/showthread.php?t=1111581&highlight=fast+dormancy

Underclocking and Overclocking: These are ways of tweaking your CPU usage. Underclocking is known for when you limit the maximum frequency, your CPU can clock to. So in laymans terms, what that transaltes to is your 1.2 GHz (1200 MHz) processor, can be changed to a 0.8 GHz (800 MHz) processor, if you were to underclock it to 800 Mhz. This is helpful to some almost completely dependant on your usage.

More elaborate, drawn out explanation: While your phone is idling, or sitting with the screen off, it is sitting at 200 MHz (lowest default - if you go lower than that your phone can become unstable [screen not turn on, etc.]), so underclocking won't help you improve battery usage much if you just keep your phone off most of the day. Undervolting would help more with that. if you however, find that you play lots of games, or mindless swipe across homescreens all day (:confused:), or perhaps photo editing apps, or other things that use the maximum cpu frequency; then you will find that having your phone underclocked to 800 MHz, forces your cpu to work less during those heavy maintence situations, but in turn, prevents heavy battery drain. What this translates to in daily use: If you play angry birds, your phone's cpu might be jumping up to 1200 MHz (depends on your kernel settings - usually it's set to ondemand, in which case it will do so) during those swipes when the bird flys across the screen. However, that is not a very cpu intensive action, so if you were underclocked to 800 MHz, you probably wouldn't see any difference (lag, stutters) in your game play. However, if you were playing a 3D defense game, or esentially any other 3D game which requires you to scroll around the map, or has many many things on the screen at once (beyond fruit ninja and angry birds), then you would notice a difference in performance due to underclocking. I mention all of this because underclocking will be most effective during those situations, but it can also be the most hindering, in those same situations. All depends on how you're using your phone and what you're trying to achieve, while maintaining a certain level of quality.

Overclocking works the opposite, if you are trying to reach a certain level of performance (you just downloaded a new 3D MMO dungeon defense game and your phone is jittering and laggy during gameplay), beyond your default 200-1200 MHz clocked cpu, you may overclock up to 1600 MHz (some devs don't like you doing it - because it is essentially quite harmful for your cpu if used for a longer period of time), also depending on the kernel (again, devs created them) you may not be able to overclock, but on the majority you can.

To Underclock you will need an app called SetCpu (or equivalent) in order to change your over-underclock rate, as well as the scaling of your kernel (ondemand, performance [max frequency, all the time], conservative, etc.), also some roms have clocking options built in (such as AOKP).

For information regarding Underclocking check out: http://xdaforums.com/showthread.php?t=1238580&highlight=underclock

If you're just straight up looking for a better battery saving rom, look here:

http://xdaforums.com/showthread.php?t=1439179&highlight=battery

If you want to know more about Android OS, and how it goes about consuming battery, check out this thread:

http://xdaforums.com/showthread.php?t=1290020

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Last but not least, if you do most or all of these methods but you're still not happy? You can always turn your phone off, I heard that saves a lot of battery ;)

If you care, leave thanks at the bottom. If not that's cool. I'm not into the whole publicity thing, I just like helping.