I have a 1983 Honda aero 50 scooter with a new battery but it keeps going dead how can I test charging system?

I have a 1983 Honda aero 50 scooter with a new battery but it keeps going dead how can I test charging system?

Read more: I have a 1983 Honda aero 50 scooter with a new battery but it keeps going dead how can I test charging system?