Here is a 6V 4.5 AH battery charger circuit which is able to charge 6V 4.5 AH SLA batteries. The schematic is very simple and using only few components. IC LM317T is the heart of the circuit. The circuit is automatic so when the battery will become full charge it will stop charging.
These type of circuits are very useful for solar garden light and can also be used in other circuits like emergency led lamp etc. Use transformer 230 AC to 9V / 500mA.