When I got my iPhone 3GS I was incredibly excited. Mostly about the video features, and the speed. I was a bit skeptical about the battery life claims with the bump in processor speed, and found that the iPhone 3GS does have much worse battery life running firmware 3.0 than the iPhone 3G does. But the source of the poor battery life wasn’t what I thought it would be.
Originally the iPhone 3G would last me about 12 ~ 14 hours from charge, or I would be down to the 20% mark at around 11 PM or so. That was fine battery life for me, since I didn’t really need to use my phone any more than that. I had everything enabled, and have awful signal quality at my house, so I was surprised by the good performance of the battery. Once I upgraded to the 3GS, the battery would need to be charged every 6 hours or so. I found myself having to plug it in in the car, at work, and basically everywhere I could find a plug. I tried turning 3G off, GPS, Wi-Fi, all of the stuff that Apple had said would improve battery life. None of it seemed to help, I was resigned to waiting for another firmware update to fix the issue, but then I turned off push.
At first, I didn’t because the original iPhone 3G had push turned on and it didn’t seem like such a big deal, but then I remembered that I didn’t have any apps on the original phone that supported push notifications. On my 3GS, I do have applications that support push. I’m not sure how Apple is doing it, but I would guess that the connection is staying open longer than with just push email, it may even stay open as long as necessary to communicate to the 3rd party server, and then back to Apple, but it seems that keeping the radios on for that long just slaughters the battery.
Once I turned off push the iPhone 3GS now lasts much longer than my original iPhone 3G. The battery life is a dream compared to my G1, as well as what I hear about the Pre. I don’t really want push notifications. I think they are annoying, the only time I would consider them would be for AIM or something, but even then if I want to chat with people, I would open the application. If someone really wants to get hold of me, they should send me a SMS telling me to open Skype or AIM or whatever. It is less battery intensive than the push process. Maybe an update will address this issue, but until then push notifications will remain off on my 3GS.