... the mobile would be power off if forgotten/inconvenient to charge. It can charge/discharge over 1000times. It's really a multi-function ... & a USB adaptor or use laptop/desktop to charge the power bank. (Notice: use laptop/desktop to charge the device, please use USD2.0 ... -2, Green LED indicator shows capacity: 25%-75%-100% 3, How to charge cell phone, iPhone, iPad1, iPad2 or MP3, MP4, PSP etc ...