that would be the greatest solution. if it really works that way. because i think new symbian phones will shut down even when charged if you remove the battery... and bundle 2 batteries together to usb reserve could be the smartest solution. one could first use two batteries with no external gadgets. and when second is wearing out, with external pack one could almost double the uptime(1100+1100mAh vs 1350mAh+1100mAh).... on an other hand, regulator eats some of the batteries power when connecting 2x3,7v -> >7v and regulating to usb 5v. so it isn't really 2200mAh compared to plugging batteries to battery contactors. maybe the simplest solution would be 6pcs cheap AA-batteries and a 5v regulator just to keep the device running during the change. could someone confirm that does the device stay on when removing battery while charging?