It's no secret that I love mophie's products, even if I do have an issue with their insistence on writing everything in lower case. Recently the good folks at Photojojo sent over a sample of the mophie juice pack reserve (US$34.95), an external battery pack for iPhone and iPod that's designed to always be at your fingertips when you need extra power, but without the bulk of a case like the juice pack air.
So how does mophie manage the trick of having extra power available just about anytime without requiring a case? It's easy -- the juice pack reserve has a key ring attached to it so it will always be with your house or car keys. It's pretty lightweight at 1.6 ounces, with a 700 mAh battery packed into a 1.5" x 3" x .5" box.
To charge the juice pack reserve, there's a flexible rubber USB cable to facilitate plugging it into an AC adapter or USB port. A tiny orange LED during charging flashes to signify that the juice pack reserve is being fed power; that LED turns green when charging is complete. When you're ready to go, the flexible USB cable is easily tucked away into the side of the unit.
When you're ready to top off your iPhone or iPod, a tug on the bottom of the unit reveals a standard 30-pin Dock connector. Shove the connector into the appropriate receptacle on your Apple device and the charging process begins. For an iPhone 4S that has a 1432 mAh battery or an iPhone 4 with a 1420 mAh battery, you're getting about a half charge -- just enough to help you out in an emergency by giving you 4 hours of talk time on the 4S or 3.5 hours on an iPhone 4.
As long as your favorite Apple device continues to use a Dock connector, you should have your juice pack reserve available. It can handle up to 500 full charge cycles; mophie notes that topping off a juice pack reserve with a 10 percent charge only counts as about a tenth of a full charge.
Like mophie's other power products, the juice pack reserve is well built. The key ring and small size make it a no-brainer as an emergency power supply for your iPhone or iPod. If you'd like backup power but don't want the extra bulk added by a case like the juice pack air, the juice pack reserve might be your best choice.
PROS: Lightweight, built-in keychain for attaching it to keys or purse strap, built-in charging cable and indicator LED, cover keeps Dock connector clean.