The Tungsten USB can be recharged on the go using a laptop computer or any micro USB cellphone charger.Powered by ASP's custom-made 18650-Lithium Ion battery, the Tungsten USB's latest XPG2 LED light produces a powerful 350 lumens of ultra-white light with a continuous runtime of approximately two hours. The Tungsten USB's battery has a protection circuit module to prevent overcharging or shortcircuiting, and the battery indicator on the light blinks red when charging and turns solid green when fully charged.