Fitbit charge 2 has a long battery life for wear day and night before you take it for a spin let's get it fully charged start by plugging the charging cable into a USB port line up the charging port with the pins on the bottom of the tracker squeeze the clamps and secure the charger on to the tracker when Fitbit charge 2 is successfully connected it will gently vibrate and display a battery image with the current charge level you'll know you're 100% charged when the battery icon is completely full charging only takes about two hours depending on your power level once you're charged you're ready to go