Like others, I've had the sneaking suspicion that the battery on my new iPhone 3GS was being consumed faster than I would suspect, given my level of usage day in and day out. My average morning usage would consist of a call or two, a few Web searches, a cursory e-mail check on three or four accounts, listening to a podcast or audiobook for an hour, and 20 minutes of gaming. By noon, I'd find the battery -- fully charged when I started -- would be hovering around 50 percent capacity.
When iPhone 2.0 came out, one of the first things I did was to disable e-mail push on days I didn't specifically need it. With that in mind, I took a few extra steps in battery management along the same lines.
First of all, I rechecked the e-mail push/fetch settings. After making sure that Push was turned off, I set "Fetch New Data" to Manual on the master control, also making sure each individual e-mail account was also set to manual in the Advanced screen.
Second, I turned off Push Notifications in the absence of anything trying to use it. On my iPhone at the moment, the only applications that support Push Notifications are the AIM instant messaging client and TapTap Revenge 2. Although I had individually disabled Push Notifications for each, I decided to also disable the master control as well -- since I'm not currently using the feature.
Lastly, I did a complete restore of the iPhone. When I got my 3GS a couple weeks ago, I did restored the settings, accounts and applications from my old iPhone 2G. In hindsight, this was a poor decision: The restore did not move a lot of data that I wanted to port to the new device (like Wi-Fi security passwords and application passwords) but may have brought some legacy bits with it that I don't want.
For instance, the complete restore and reconfiguration from scratch resolved some of the Bluetooth difficulties I wrote about in my review of the new device. Specifically, the BlueAnt Supertooth 3 speakerphone that wouldn't work with my 3GS suddenly worked fine.
As for battery performance since I made these modifications, it's only been two days but at first glance things have improved. On the first day, the normal amount of morning usage I described above left about 80 percent remaining capacity. Subsequently, I used the iPhone as normal throughout the rest of the day, did not charge my phone overnight, used it as normal on the morning of the second day -- and I now find myself with 46 percent remaining capacity.
A small sample size, to be sure, but so far so good.