QuickerTek has introduced the US$29.99 Little Black Box (http://www.quickertek.com/products/ipad_charge_monitor_usb.php), their new USB battery pack that allows you to use any AA battery to charge or power Apple’s iPhone, iPad, iPod touch or virtually any USB powered device.
The Little Black Box is compact so you can take it on an airplane, camping or road trips. That means you can use Alkaline, Carbon, Ni Metal Hydride or NiZinc rechargeable AA batteries as long as all four AA batteries are the same kind and brand. The internal circuitry compensates for different battery voltages to supply the correct voltage for USB compatibility.
QuickerTek says its test studies show that the best batteries to use are the rechargeable NiZinc batteries, they are the highest capacity (mAhr). The Little Black Box has a one-year parts and labor warranty.