Up until two days ago, I was using an outdated iPhone 3G with horrible battery life. On a usual day, I would need to go recharge my battery two or three times with moderate use. Charging the phone everytime I entered the car and was on the computer became the norm for me, but that shouldn’t have to be the norm for you.
It is at this point that I introduce the PowerDuo Reserve from Griffin. Gone are the days of those horrid ten-percent battery life warnings on the iPhone. The PowerDuo Reserve will essentially allow you to carry a small rechargeable battery around that will recharge your iPhone on the go. Included in the PowerDuo Reserve package is the external rechargeable battery, a car charger, and a wall charger. While the main focus of the chargers are to give the external battery a charge, it will also charge your iPhone at the same time assuming you have your USB cable. It only takes about a hour to fully charge the external battery using the included chargers.
The external rechargeable battery is pretty small and has a rubber texture to it to avoid getting beat up when in your pocket. There is a button on the front that will light up LEDs to tell you approximately how much battery you have left. We tested the the battery pack with our iPhone 3G and iPhone 4 and found that it worked on both devices, although the iPhone 4 is not yet listed on the Griffin site. We found no problem carrying around this small battery pack with us and found it useful on numerous occasions.
The PowerDuo Reserve will run you $59.99 if you buy it from the Griffin website. Check out the listing here.