A basic car battery charger usually charges at 2 amperes. On average, car batteries hold 48 ampere-hours, so it typically takes a full day to charge a car battery. However, there are other car battery charging solutions that offer up to 10 amperes.
Fast charging is not usually recommended, as it can damage the battery plates. Car batteries also have a separate type of ampere — the cold crank ampere — that refers to the amount of power the battery can supply to start the engine. Depending on the manufacturer, a car battery can generate anywhere between 400 and 1,500 cold crank amperes.