[AT&T, Rogers, Bell, Telus Samsung Galaxy S III] flammingcamel:
I have done pretty extensive testing in the last few days and this is what I found.

TOUCHWIZZ USERS ONLY, uninstall and delete data for the app my uploads. It syncs your gallery with picasa and uses a load ofdata and battery. It won't break anything. turn off instant upload in Google+. Turn off smart stay and motion actions. they use about every sensor in your phone. Turn off the wake up phrase in s-voice. If its on it is always listening for that phrase. I'll keep looking for other things but I got fairly good battery life just doing those things right there.

When uninstalling an app, wipe cache and data first. This will clear any background processes that could stay after the app is gone.

Install es task manager and kill everything you don't need to run on startup to preserve boot time/battery usage. Also it will keep the processors a lot lower.

All accelerometer and other hardware functions use a significant portion of your battery. If you don't use landscape mode turn auto rotate off because it uses that precious battery life.

Weather bar in notification drop down and on your lockscreen will destroy your battery life. Weather widgets also use quite a bit of battery.

Facebook app also kills your battery because its always connected to the internet. Syncing Facebook account to your phone further wears down your battery. Any game or other app that connects to facebook will also do the same.

Look in data usage under settings. Anything on that list uses more battery because its connected to the internet.

If your not in an lte area turn lte mode off because your device will be searching for a signal it will never get.

Low signal strength kills your battery because your phone has to use more energy to hold connection to the network. If you have WiFi at home and bad cell service (or anywhere) use WiFi because its easier it is for your phone to hold good wifi signal than bad cell signal. also turn off your NFC. It uses more battery than Bluetooth does.

Get better battery stats app and look for wake locks because without deep sleep you will never get more than 12 hours battery life.

Widgets, live wallpapers, lock screen ripples and other things that move use battery also. If you don't use it then remove it to save a couple percent a day.

Remember that when charging through a computer USB port or things like that charge a lot slower than an outlet. Slow charging is better than fast charging because your battery stays cooler and that means your batteries total life will be longer.

Finally before you go in a ROM thread and start complaining about battery life, go at least three charge cycles after flashing to optimize your battery.

There are many things that cause battery drain so beware when you download that next app. It could be a battery sucker. If you don't need or don't use an app. Uninstall it because it may have background processes that are using up battery and RAM.

This is a link to read about charging and discharging li-ion batteries.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Thank x10forevers for this great piece of literature. :thumbup:

Here is a link to how Att suggests you save battery!:thumbup:

http://insider.att.com/articles/kee...ExtndSource=1012_ipnp_nat_i_btry#.UJJiM6O3PFo

PM me if you have further questions or something for me to add to this OP.

Happy flashing everyone!!! ;)