I'm trying to figure the same thing out. I returned one because i could never get more than 5 hours of usage on a single charge. I never watch video/youtube, it's all ipod, phone and safari/google maps usage. My new one doesn't seem much better, but even the apple genius said they don't really have a good gauge to see if the battery is lasting as long as it should. If i could get 6 hours of usage and still have 30% battery life left, I'd be happy. Consider yourself lucky.
I don't enable bluetooth, but I am usually connected to WiFi when browsing, EDGE for google maps.
Looking at the apple iPhone site, it lists the MAXIMUM battery life as:
iPhone offers up to 8 hours of talk time,(1) 6 hours of Internet use,(2) 7 hours of video playback,(3) or 24 hours of audio playback(4) on a full charge at original capacity. In addition, iPhone features up to 250 hours of standby time.
I guess a good test would be to follow their video playback testing:
Video Playback: Testing conducted by Apple in May and June 2007 using preproduction iPhone units and software. Video content was a repeated 2 hour 23 minute movie purchased from the iTunes Store. All settings were default except: Call Forwarding was turned on; the Wi-Fi feature Ask to Join Networks and Auto-Brightness were turned off. Battery life depends on the cellular network, location, signal strength, feature configuration, usage, and many other factors. Battery tests are conducted using specific iPhone units; actual results may vary.
Anyone else experiencing this <5hr usage/charge cycle? I'd like to figure out if I'm doing something wrong to have my battery life suck so much on two different iPhones. I'll have a third to try when I return this one because of the stuck pixels. I wish they would put more information in the "Time since last full charge" section, like break out the Usage to phone, video, music, WiFi, EDGE, etc so we could have a better metric to see if our battery sucks or not.
It really sucked when the battery went out halfway back from a 3 hour trip where I was touting the iPhone to the rest of the car because we were taking some backroads, then we were on our own out in the middle of nowhere.