i have a national company bike battery and 3 ampere 12 volt charger i want to know how many hours needed to fully charged the battery sorry 4 my bad english
What does the battery label state? Usually it mentions voltage and capacity (amp-hours). Sometimes it also mentions maximum charging current or charge voltage.
there is nothing mentioned on battery except only says 4+ power
Usually small bike batteris are near 5 amps . According to battery manufacturers battery charging amps should be 10% of the battery total amps. You should use maximum of 1 amp 12v charger you can make it yourself by this tutorial Battery charger tutorial