So here’s an update on my post last week about trying to extend my iPhone 4S battery life by switching mostly to 2G (EDGE) instead of using 3G.
On heavy usage, the difference is somewhat noticeable — nothing that blows my mind.
On light usage though, it’s a lot more interesting. As of 2 p.m. today, I’ve had my phone off the mains for a little over two full days and the battery shows 54% capacity remaining.

That’s with very light photography,a few phone calls, a little bit of texting, some Internet radio streaming on my drive to work*, light web browsing using Opera Mobile as my browser.
My screen brightness is set to auto with the slider sitting above the letters gh of the word Brightness in the menu.
No video, a bit of Wi-Fi.
Not too shabby.
(*) On mobile Internet radio streaming, that’s where it shows the most noticeable change in battery usage. On my 15-minute commute to work, it typically drains 5% or 6% using 3G. On 2G, it only drains about 3%. That’s something resembling half the previous usage. Nice.