Battery life with 3G enabled was 4 hours and 44 minutes, down from nearly 6 hours when I tested the original iPhone. Turning off the 3G modem and switching to Edge, my call time went up to 6 hours and 4 minutes, about where it should be based on my original iPhone test results. With less than 5 hours of talk time, if you plan on doing a lot of talking you had better shut off 3G mode on the iPhone.
New wireless data technology made the iPhone, as experienced right out of the box, a worse battery experience than its predecessor. The next iPhone, dubbed the 3GS, upped its battery to 1219 mAh, inching back toward the original iPhone's 1400 mAh. Apple claimed the 3GS offered 12 hours of talk on 2G/Edge networks (two more hours than the 3G, four more than the original iPhone), a now-realistic five hours on 3G, and 300 hours of standby, the same as the 3G. In reality, we turn to iLounge:
When used on 3G networks either as a phone or data device, it achieves only a meager 5 hours of calling time on a full charge -- the same as the iPhone 3G -- and even less if you're using features such as Bluetooth or GPS at the same time. In a mixed-mode test. . . the iPhone 3GS's battery lasted for 4 hours and 44 minutes of actual use, with an additional 17 hours on standby. . . iPhone 3GS's poor battery life thus makes it a bad choice for road warriors who have heavy calling needs.
Compare iLounge's take on real-world 3GS use to the AnandTech's 3G review: four hours and 44 minutes each, on the dot.
Next was the iPhone 4, which was, on many fronts, the biggest change since the beginning: a high-density Retina display, a notably new design, and a 1420 mAh battery somehow shoved inside, 20 mAh over the original. Apple’s statements on battery life claimed seven hours of talking on 3G, 14 hours on 2G (compared to the original iPhone’s 8-hour claim), and 300 hours of standby time. In testing, MacWorld’s heavy usage saw the iPhone 4 lasting about an hour longer than a brand-new 3GS, while iLounge plainly stated that the iPhone 4 had battery life “roughly equivalent to original iPhone.”.