Recently I discussed my power problems with using my iPhone as an e-book reader. Today I'll discuss a couple of add-on power sources that I use and have previously reviewed at other websites.
Perhaps the most cost-effective, especially if used with rechargeable batteries, solution is the Turbo Charge, pictured above. The unit sells for $29.95 and is powered by 2 AA batteries. Just plug it into your iPhone/Touch/iPod and it will fully charge the batteries. It is not really convenient to use in real time with the iPhone, as it dangles in a rather inconvenient manner. There are two real plusses to this unit. First, you can order individual adapters for various portable machines. I use this with my Treo, Palm TX, Nokia cellphone and Windows mobile phones. Their website lists adapters for bluetooth headsets, TomTom GPS units, and almost any phone you can think of. Second, since it uses plain old AA batteries you can find them anywhere and thus you are not limited to one "recharge" of the unit.
The second alternative is a dedicated charger for the iPhone/Touch, such as the Mophie Juice Pack pictured here. This unit is a sleeve and the iPhone/Touch just slips into it like a case. The unit contains a non-replaceable rechargeable battery. According to their website the Juice Pack will increase standby time to 350 hours, talk time to 6 hours in 3G, 6 hours WiFi use, 28 hours audio playback and 8 hours of video playback. I have verified the audio and video times, but not the others.
The advantage of the Mophie is that it integrates the phone and charger into one unit and you really don’t need to take it off. Your iPhone/iPod charger will charge both the phone and the Mophie at the same time. The disadvantages of the unit are that it costs $99 and that it is rechargeable. You cant’ carry a pair of spare batteries to use in an emergency, like you can with with Turbo Charge.