Car Battery Charger Circuit Working Principle:
This is a simple car battery charger with indication. The battery is charged from a 230V, 50Hz AC mains supply. This AC voltage is rectified and filtered to obtain an unregulated DC voltage used to charge the battery through a relay. This battery voltage is constantly monitored by a feedback circuitry compromised of a potential divider, a diode and a transistor. The relay and the feedback circuitry are fed by a regulated DC voltage (obtained using a voltage regulator). As battery voltage increases beyond maximum, the feedback circuitry is designed such that the relay gets switched off and battery charging ceases.