The EGO II Twist uses a 2200mAh rechargeable battery with power saving and safety features that allow you to turn the battery on and off. The battery is equipped with a microchip to prevent overcharging and will stop automatically when it becomes fully charged. Under normal conditions, the battery takes 3 hours to charge.To charge, plug the USB charger into the top of the battery and connect to a wall adaptor/socket or a USB port that is powered on. The battery’s indicator light will flash to show it is charging. * Use only the provided USB charger to avoid damaging the battery. * For the best charging performance, use USB ports with high voltage levels (low voltage ports might not charge the battery properly). Please consult your computer’s user manual and/or the manufacturer’s online information to find out which USB ports have high voltage. *Fully charge the battery before you first use it to achieve/maintain optimal battery life The battery is shipped in the “off” position. To activate, press the power button 5 times in a rapid succession (within 2 seconds). Charge the battery to its maximum capacity every time to achieve and maintain the optimal, long battery life. Do not store the battery in a hot/humid environment and avoid dropping from a height. Be gentle when connecting/disconnecting the charger and dismantling/reassembling tank parts. Never puncture the battery; if the battery is accidentally punctured, use protective hand-wear and dispose of it carefully and responsibly. The GS EGO II Twist is a new generation of variable voltage system, consisting of Rechargeable Battery and BDC Tank Atomizers. Constructed entirely from stainless steel and heat resistant Pyrex glass, it incorporates precision manufacturing and uncompromising perfectionism, only from trusted brands!