Stay Charged with External Battery Packs
If you're constantly on the go and rely heavily on your iPhone to hold conversations and surf the Web, the built-in rechargeable battery in your Apple mobile device might not make it through the day. Of course, you can continue to use your iPhone while it's plugged in and recharging via an electrical outlet or a USB connection with your computer, but this option diminishes the phone's wireless portability. While in the car, you can invest in an optional car charger, but this also has limitations in terms of convenience.
Several companies, including Brookstone, RichardSolo, and Mophie, offer small and thin rechargeable external battery packs that can double, triple, or quadruple the battery life of your iPhone, depending on how it's used. These external battery units connect to the iPhone via the phone's Dock connector. Some even double as protective cases for the phone itself (adding just a bit of extra thickness, but lots of extra talk time or web surfing time).
Plan to spend $50 to $100 for an ultra-thin external battery unit that dramatically extends the battery life of your iPhone. Between uses, the battery pack can be recharged using a mini-USB connection with a powered-on computer, or by an electrical outlet.