the charger cuts off the charge automatically when the battery is full.
There is an LED on the charger which goes red when charging, green when it has finished changing.
Every mile you ride on battery will require about 6 minutes charging time, 10 miles = 1 hour charging time.
It is best to ride and recharge often.
If you don't use the bike for a long time, it's better to keep the battery around 75% full, not totally full. That is, charge the battery to full then ride about 7 miles before storage.