First, plug the charger into the battery. Then connect the wall cord to the charger block and then insert the plug into a 120v AC outlet. 

The light on the charger should be RED, and that light will change to GREEN when the battery is fully charged. The charger that comes with your bike has internal controls that prevent overcharging of the battery.We do not recommend leaving the unit plugged in for extended periods of time.  In addition, we do not recommend using the charger unit in poorly ventilated spaces such as closets or drawers, as it may overheat.