The battery comes charged and ready to go, just screw on the tank and puff. No button. No fuss. The light on the bottom of the battery lets you know it’s working. A slow draw is all that is necessary to activate the battery. When the light starts to blink it’s time to charge it. Unscrew the tank, screw the battery into the USB charger and then plug it into your computer or wall charger. The light on the USB charger will change from red to green when it’s ready to go.