You can work out charge times of a battery and charger by looking at the mah of the battery that will be written on it and the mah OUTPUT of the charger that will be written on the charger.

Dividing the mah of the battery by the mah of the charger will give the charge time in hours. For example, if the output on the charger was 300mah and the battery was a 650mah then 650 divided by 300 would give 2 hours and 10 minutes.

Be careful never to over charge a battery as this will damage it.