MP3 Players: The truth about your battery life

One of the key specs you mustn't ignore before purchasing an MP3 player is its battery life. This number, whether it's 14 hours or up to 35 hours of audio playback, gives you an estimate of how long your gadget will play tunes on a single charge (in the best-case scenario)
For most manufacturers, the perfect scenario requires that you play only MP3s encoded at 128Kbps; you're wearing bundled earbuds; your volume level is at about 50 to 75 percent; the backlight of your screen turns off automatically within 5 to 10 seconds; your equalizer setting is flat or normal; there are no DSP settings (such as the iPod's Sound Check) enabled; you listen to your music in one, maybe two sessions; and if applicable, you don't view any photos or videos. Given that these conditions are rarely ever met in the real world, you'll never achieve the number x in "up to x hours."

That's OK. If battery life is your primary concern-and it may be for world travelers-then you'll naturally go with a player that has at least 20 hours of rated battery life per charge or AA (or AAA) battery, as stated in the player specifications. This figure is rarely ever left out of specs, by the way. The best hard drive-based players last more than 20 hours--such as the Sony NW-HD5 and the Cowon iAudio X5L; the best flash players--such as anything from Sony, Samsung's YP-T6, and iRiver's T10--last more than 40 hours.

Apple iPods typically outperform the company's ratings. In the tests, the 30GB 5G iPod lasted 14.5 hours, 30 minutes longer than what Apple claims.  Factors such as sound quality, features, format compatibility, and looks may overshadow battery life, but when your player runs out of juice, it doesn't really matter which features it has or how good it sounds.

In the real world, there are plenty of factors that will help drain your battery much quicker than you'd like. For example, while the iPod's 14-hour audio-only rating is acceptable (the first iPods had 8 to 9 hours per charge), you never get that many hours, and in fact, you average less than 8 hours. The battery isn't dying prematurely; rather, you may like to have screen on and browse photos, as well as watch an occasional video and crank the volume up.

Those who belong to subscription services such as Napster or Rhapsody have it worse. Music rented from these services arrive in the WMA DRM 10 format, and it takes extra processing power to ensure that the licenses making the tracks work are still valid and match up to the device itself.

Yet, here's another reason why we should still be ripping our music in MP3: better battery life, the most obvious reason being universal device compatibility.

Sony is one company that's been more up front about digital audio playback times. The company's players tend to have the best rated battery life, consistently more than 40 hours, but this is playing its own format, ATRAC3, at a lower-than-typical bit rate.
Basically, rated battery life should be used as a guide and never be taken literally.