AMPY stores the energy you generate in the internal lithium ion battery. Simply plug in your smartphone or wearable device into the USB port to start charging. In a hurry? We engineered AMPY to charge your devices just as fast as a wall outlet. 

AMPY's internal battery stores about a week's worth of physical activity and stays ready to use for months. You can also recharge AMPY from a wall outlet if needed using the micro-USB port on top.

This unit is still in it is original packaging and has not been opened.  Thus it has not been tested.