Hallo Alisha,

a good charger for lead acid battery is current regulated AND voltage regulated. So, your resistor diode combination indeed might be able to achieve some current limiting. But it does not achieve any voltage regulating: If voltage of battery rises up to 14V, current should be switched-off.
Not having any voltage regulation is dangerous, especially when dealing with high charging currents, because above about 14V H2 and O2 is produced!

Bye,
Kai