A smartphone that lasts all day can be a life saver. While trendier phones like the iPhone 5 can last a good six hours or more, some models are rated for a full 20 hours or more, which includes heavy data usage. Here are my top picks.

1. Motorola Droid RAZR M

This brand new Android-powered phone, which works on the Verizon network, is rated to last a surprising 20 hours of normal use--checking email, browsing the Web, and even checking YouTube clips. (Some smartphones give you only the "talk time" rating for usage.) The phone still has a sharp 4.3-inch screen that uses a technology called AMOLED--so, it's bright and clear but not power hungry. One important spec: Even with the amazing battery longevity, the phone still connects to Verizon's high-speed LTE network. Turn off some of the wireless options and you'll get even better battery life.

2. Lumia 920

Keep an eye on this new Windows 8 phone, which should be available in late October. The battery life is rated at 17 hours for talk time, but 10 hours for data use. That's about four hours longer than the iPhone 5 and much better than many Android phones on the market. The main perk to this phone is the camera, which uses image stabilization techniques, shoots in low light, and can even take multiple shots in succession. The Windows 8 tile interface is also easier to use.

3. Samsung Galaxy SIII

Another phone with an AMOLED display (a stunning 4.8 inches), the SIII is rated for nine hours of talk time, which is a bit less than the Lumia 920 but still higher than many Android phones. But it also has some rather unique battery-saving features. For one, the phone knows when you are looking at it. When you look away, the Smart Stay feature dims the screen automatically. Another bonus: The SIII is the "halo" phone for Samsung, which means they make extra accessories for it, like a dock for charging up.

4. Motorola ES400S

This is one of those old-school phones from a few years ago, but it has one clear advantage: It will last about 12 hours of talk time and won't break easily. Since the older Windows 6.5 operating system is on board (one that is now two versions out of date) you won't see any snazzy apps or multimedia tools. However, the phone is ruggedized for serious field use. You can drop the phone, use it on a wintry day--even spill water on the screen and expect it to keep humming along all day, without getting damaged.