... bag,solar energy backpack. 1)power supply for laptop,mobile phone,MP3/MP4 2) ... to the shoulder strap, Includes a 2,200mAh Li-Ion battery pack with 3 voltage settings to store solar power.When ... not in the sun, the battery can be charged using the AC travel charger or DC ... , and generate up to 4 watts of power. The Voltaic Backpack is built tough for use as a weekend hike bag ...