I hope this isn't a serious post. A car battery is over 12 volts, while a AA battery is a bit over 1.5 volts if alkaline or NiZn, and >1.2 volts if NiCd or NiMH. NONE of these chemistries are designed to be charged by applying 12+ volts to them, and if you want the rechargeable batteries to last, there is a charging algorithm (varies depending on battery chemistry) to maximize battery life.
-Rod