iDynamo is powered through the iOS device. It only uses power during a transaction. To charge your iOS device while the iDynamo is attached, connect the micro-USB cable (micro-B) (MagTek Part #30019324) to the back of iDynamo and then connect the opposite end (USB-A) to the appropriate Apple charging adapter. Apple 12W USB Power Adapter for iPad and iPad with Retina Display. Apple 5W USB Power Adapter for iPhone, iPad mini, or iPod.