I got an extended battery on eBay for $6, and it makes a huge difference. I'm trying Mobster ROM, and my battery was draining very fast...I was getting just a few hours of use (like 3). My screen is on constantly as I text and browse the web a lot, throughout the day. After I got the battery (this week), I went over a day without charging, with a screen on time of over 3 hours, and my battery wasn't dead yet. Once I switch back to stock I expect the battery life to be way longer, and if I didn't use my phone so much, it would be even longer. It's a little bigger and heavier, and I can only use the case that came with it, which is too bad since I like to change the look of my phone, but it's definitely still worth it.