I recently bought an APC UPB50 external battery from Circuit City... [url="http://www.circuitcity.com/ccd/productDetail.do?oid=164357&om_keycode=58"]http://www.circuitcity.com/ccd/productD ... keycode=58[/url] This model is relatively small, about as wide as the AA1 and 2.5" deep. It weighs about a pound. I've found that under constant use it provides roughly 3 hours of power, which added to the AA1's 2.5 hours of battery life yields over 5 hours of uptime. The unit comes with a collection of adapters for various laptops...use the K set for the AA1. I'm pretty happy with the device. I travel fairly frequenty and the extra hours of uptime are great when I'm sitting in an airline seat that has no power plug. Perry [url="http://www.kidpub.com"]www.kidpub.com[/url]