There is a rumor unspoken rule : the slower charge the better battery, it seems charging current is around C/10 and
A car battery needs a charge of 12 volts to start. The amount of charge that a battery can hold depends on the size of the battery and the number of cells. A typical car battery has six cells, each of which can hold a charge of 2 volts. So, a fully charged car battery will have a total charge of 12 volts.
foJZam.