how long do i charge a car battery before it is fully charged
A fully charged â12 voltâ battery will be at about 12.6V The charger may well take it up to 14.4 or so while charging. About 12.2 volts is 50% and 11.8 is approaching dead. (these voltages at no load, the battery at rest). Anything under 11.0 may indicate a dead cell.uring the constant-current charge, the battery charges to about 70 percent in 5â8 hours; the remaining 30 percent is filled with the slower topping charge that lasts another 7â10 hours. The topping charge is essential for the well-being of the battery and can be compared to a little rest after a good meal.