Battery Technology Battery Extender II for iPod with Dock Connector (White) Compatibility: iPod 3G, 4G, 5G, 6G; nano 1G, 2G, 3G; iPod touch; iPod mini 40-hour battery pack Lithium ion battery can be charged an average 400 times and at up to 40 hours per charge 16,000 hours of music play time or download time and will send power directly to the iPod without charging the internal battery