There are several out right now, you can check amazon.com for choices. Although I haven't purchased it myself, there is a combination case/extra battery also at amazon. What someone needs to develop is a case with a holster that acts as an external battery that way every time you put it in the holster it will recharge or "top off". This is feasible now since lithium batteries do not suffer from the dreaded memory effect.
I use JuiceDefender Ultimate and I get at least 24 hours out of a single charge. I'm on my phone contantly (texting, calls, FB, my 4yr old daughter plays with apps) and I think there was 1 time I made it 18 hours and my battery got underneath 18%. I think this phone's battery blows any other phone's battery out of the water! My boyfriend got jealous because my batter lasted longer than his iPhone battery lol.
After a few chargers, it does get better. However, using the power saving mode makes the screen way too dark. I'm still going to purchase an extended battery when it comes out. This phones still burns through battery faster when you use it. I guess I'm more disappointed since battery life was touted as being much better; a feature highlight.
I had lower battery performnace when I first got this phone. It takes a few charges for the battery to hold a better charge. Enabling the pawer savings mode helps. Disbaling some of the sync features on your google account can also help. There is also a good day of sync that goes on when you first set up this phone if you use an common smart phone features.
I've diabled the Sprint Connections Optimizer as well, I found this to have a HUGE drain on battery life rather than helping.
My battery life has been totally awesome until I started having the Facebook lockup issue a few days ago. That seems to be dinging my battery life a little bit, but it's still solid. Sometimes I even forget to charge it at night and there's plenty of battery to get me to work the next day.
Yes... doing battery memory setting is important for good battery life... I just got mine on Saturday night and haven't done it yet but am planning to today.. It does seem to recharge slowly since out of the box I had about 50% and used it for a while before plugging in.. At least in the car, it was slow to recharge.. Suspect the home charging would be faster so I'll run it all the way down today and try it later on.. Running on WIFI at my office, it has very little usage in idle..
I have had nothing but long lasting unplugged joy with my new SIII. Not sure why your battery is draining so fast. I upgraded from the original Epic and battery life sucked on that phone. I have gone all day 7a.m to midnight without plugging in for a charge. I've would consider my usage moderate to intense during the day. I do notice the battery does seem to drop more while I'm at work, but I think thats because of a bad 3g signal. I can have 34% charge at 5pm and it will last the rest of the day. One tip I followed which I'm not sure applies to the battery type used in the SIII, the first three charges I allowed the battery to drain all the way down to zero, then fully charged it before using again. Again I am more than pleased with the battery performance of this Galaxy!
I am regretting my purchase of this Galaxy S III phone. The battery life is awful, even with everything turned off. I'm sorry I upgraded from the Galaxy S II since there is really no huge difference in phones. At least I was able to use an extended battery in my Galaxy II. It sucks to pay for LTE when you can't even access it.
What is bad for you though? I just turned mine on today finaly. I've spent all day playing with the phone, customizing everything. The battery went from full charge to under 25% in just over 6 hours of near constant use. I don't consider that to be too bad for the amount of use. One thing I would suggest is to use the wifi. It will actually use much less battery than using Sprint's network will. It's also pretty unlikely that you will find wifi anywhere that is slower than Sprint's 3g.