Audio Player Tips
Avoid skipping: If you use an audio player with a hard drive, you can save quite a bit of its power by selecting a playlist and then letting the device play uninterrupted. Because hard-drive players buffer songs in memory, they don't have to read continuously from the disk. Reshuffling tracks, skipping ahead, rewinding, and pausing the music require more reading operations, all of which consume more power.
Play smaller songs, get longer life: Your player will last longer playing 1000 5-minute songs than five 1000-minute songs, because with shorter songs the device loads full tracks into memory, reducing the need to access the hard drive. Break long songs into multiple tracks, or compress them at a lower kbps rate.
Do away with the backlight: Disable the backlight or set it to turn off quickly. The less light you use, the more tunes you'll hear.
Keep it cool: Batteries work via chemical reactions (see "Why Don't My Batteries Last Long Anymore?" for more), and extreme temperatures can make batteries work harder to generate the same amount of power. Thus, Apple recommends keeping your iPod running at between 32 and 95 degrees Fahrenheit, and specifies 72 degrees as the optimum temperature. Remember, a leather case can act as an insulator, increasing a device's risk of overheating.
Ignore the equalizer: Tweaking the bass or the highs makes a player's processor do extra work to alter the sound. Set the equalizer to off or to zero decibels to maximize the playing time.
APC Auto DC to AC Inverter
Plug apc's converter into your car's cigarette lighter, and you're good for up to 350 watts of power. It won't add much weight to your bag, either--about 3 pounds. ($40 and up, depending on wattage; www.apc.com)