Description

This is a lead-acid battery charger circuit using IC LM 317. The IC here provides the correct charging voltage for the battery. A battery must be charged with 1/10 its Ah value. This charging circuit is designed based on this fact. The charging current for the battery is controlled by Q1, R1, R4, and R5. Potentiometer R5 can be used to set the charging current. As the battery gets charged the current through R1 increases. This changes the conduction of Q1. Since the collector of Q1 is connected to adjust pin of IC LM 317 the voltage at the output of LM 317 increases. When the battery is fully charged charger circuit reduces the charging current and this mode is called trickle charging mode.

Circuit Diagram

PCB Layout

3D Diagram