As a general guideline, a 12-volt battery with a capacity of around 50Ah will take approximately 2.5-3 hours to charge from a fully discharged state using a 30-amp charger on a slow charge setting. However, it's important to note that this time may vary depending on the specific battery and charger used.
To determine the exact charging time, it's recommended to refer to the manufacturer's specifications for both the battery and the charger. These specifications will usually provide information on the recommended charging current and time for different battery capacities.
It's also worth noting that charging a battery too quickly can shorten its lifespan, while charging too slowly may not provide enough power for the intended application. Therefore, it's important to follow the manufacturer's guidelines and use the appropriate charger settings to ensure optimal battery performance and longevity.