This product is a rechargable emergency backup battery for your portable devices that have USB or mini/micro USB charging ports. I tried it out with my iPhone 3GS since its battery life is now only about a day, less than that with heavy use. First up the unit recharges by plugging into your computers USB port. Recharging takes about 2 and a half hours. There is a sliding switch on the side to turn the battery off to preserve the charge for longer. To charge my iPhone I needed to have the iPhone USB cable handy. Plugged one end into the battery and the other into the iPhone and hey presto, the iPhone has battery again! The only draw back with this unit is that if you have remembered to bring your iPhone charger cable then you probably wont need it! For me it would be more useful to get a spare iPhone charger that runs off the car cigarette lighter socket like the Griffin power jolt. So in summary, the unit works well but think carefully whether it will be worth it for you!
For people on the go, this is a handy little device. And it is little: smaller than the average mobile phone.
Once charged up by USB - it took my unit just short of 3 hours to reach full charge out of the box - it can charge devices via USB, mini USB (using cable) or micro USB (using cable + adapter). It works fine with Amazon's Kindle and iPods of all descriptions, but not iPad, which has a higher power requirement than most mobile devices.
As handy as the charger is, it's not perfect. I would have liked it to come with a mobile-friendly protective case, and a dedicated AC power port/adapter might have helped to reduce its overall charging time. The never-at-home might be better advised to shell out a bit extra for the Duracell 5 Hour Mobile Phone and MP3 Portable USB Charger.