How to charge safely: 1. Connect the wall charger to AC socket first, and the led of the charger will light green. 2. Then connect the charger with battery. Will not charge? Please contact seller immediately to replace a new charger. Modle: NB7101. Capacity: 25.9V 2.5Ah or 3.7V/17500mAh. It's just a different way of calculating, actually the same capacity. Total 64.75Wh.