[AT&T, Rogers, Bell, Telus Samsung Galaxy S III] Yetamedi:
I have now had two different versions of the galaxy s 3. The first was with verizon, but after the encrypted bootloader deal I bailed and switched back to at&t. The verizon one I had for about 5 days total before reboxing it send back for a refund. Here are my observations after using both devices. Note these are purely observations and not objective tests in any form.

My verizon branded S3 suprised me with its battery life. I had previously owned a galaxy nexus and its reputation for having poor battery life was well founded. I was lucky to get 2 hours of screen on time per full charge. I became accustomed to plugging it in at work if I wanted to make it a full day with moderate usage. With that in mind I was leery of the S3 with it being another samsung device on the same network (with the same sized battery even). What I got though was a device that was lasting me all day (14+ hours with over 4 hours of screen on time). This was well beyond my expectations. After owning the device for five full days the results were consistent, but I was more than tired of verizons anti-consumer tactics so I bailed to at&t and got another S3.

My at&t branded S3 did not get nearly the same batty life that I had seen out of the verizon branded one. On one particular day I noted it dying after having only an hour and a half of screen on time. Something that I had noticed though between the two devices was how I was charging them. When I got the verizon branded one it was during the week of the 4th. I was off work all that week and was spending a lot of time in front of my computer. My S3 being a new toy to play with was subsequently charged via USB using the provided cable from samsung. I had observed that it charged rather slowly that way but didn't care so much at the time. My at&t branded S3 though was charged via my usual method of plugging the phone into the charger beside the bed right before going to sleep and unplugging it before going to work the next morning. I used the provided samsung charging block but a different USB chord.

Once I noticed that I had charged both devices differently and had gotten different results from them, I charged my at&t version the same way via USB. When I did that I got 14+ hours of charge out of it with a whopping 6 and a half hours of screen on time. I have no concrete proof that charging the phone this way is what got me such drastic differences in amount of use out of the phone. Further more there are multiple variable which could play a role.

One: is using the provided cable from samsung vs another USB cable a factor? I throw this out there as a factor because I read somewhere that samsung tweeked the voltage slightly with this battery. With that in mind perhaps the current draw to the battery is slightly different.

Two: does the fact that it seems to charge much more slowly over USB from a computer also a factor? I present this as a "trickle charge" sort of variable. Perhaps the phone is getting a more complete charge by charging more slowly in this manner.

Three: when I had made this observation I also remembered that my old galaxy nexus had an issue where if you hit the power button to power off the screen it wouldn't go into deep sleep mode. You had to let it time out on its own (not sure if this was a real issue or not, just remember it being talked about and it seemed to help). So I also began using this technique as well with the new at&t S3.

Both of my phones were set up the same way. I set the screen brightness to about 40% and only turned off wifi when I wasn't at home. GPS and data were left on while at work all day. It should be noted that on the day I got to 6 1/2 hours of screen on time, a good 4 of those hours were spent in the nook app reading a book. I keep the nook app set to night mode which has a black background with white letters as it is easier on my eyes. Two full hours were also spent watching True Blood episodes on the HBO go app.

I do not claim to be an expert on these matters. I am not an electrical engineer and could very well be talking out my ass. My observations are purely that, nothing more than my own personal observations. If however we could get a dialog started about how everyone is charging their devices we might be able to narrow down what reliably works vs what is not with our S3's (barring defective hardware issues of course).