Since the diode will conduct only when battery voltage reaches 14.4V, the values of resistors should be such that the positive voltage fed to the diode is at least 3V when battery voltage is around its maximum. The filter capacitor value would thus be calculated to be around 10mF.ĭesigning of the feedback and load section involves selection of resistors for the voltage divider section. Thereby the ripple would be around 4V (Peak voltage of about 15V and input regulator voltage of around 8V). Here we are using a voltage regulator LM7812 to provide a regulated 5V supply to the relay and the 555 Timer.

Since here we are also designing a regulated power supply, the maximum allowable ripple would be equal to the capacitor peak voltage minus the required minimum input voltage for the regulator.

Here we select diodes 1N4001 with PIV ratings of about 100V.

Since here we are using a bridge rectifier, the PIV for each diode should be more than four times the peak AC voltage, i.e.

Now the required RMS value of AC voltage is around 12V, the peak voltage would be around 14.4V, i.e.15V. Since required load voltage is 12V, we can settle for a transformer with 12V/8A rating.

Now the required transformer secondary current would be around 1.8*4, i.e.

Since the charging current of a battery should be 10% of the battery rating, the required charging current would be around 4A.

Here the desired load is a car battery with rating of about 40AH.

To design the entire circuit, we first design three different modules- the power supply section, the feedback and the load section. As battery voltage increases beyond maximum, the feedback circuitry is designed such that the relay gets switched off and battery charging ceases.Īlso get an idea about How a Lead Acid Battery Charger Circuit Works? Car Battery Charger Circuit Diagram: Car Battery Charger Circuit Diagram Car Battery Charger Circuit Design: The relay and the feedback circuitry are fed by a regulated DC voltage (obtained using a voltage regulator). This battery voltage is constantly monitored by a feedback circuitry compromised of a potential divider, a diode and a transistor. This AC voltage is rectified and filtered to obtain an unregulated DC voltage used to charge the battery through a relay. The battery is charged from a 230V, 50Hz AC mains supply. This is a simple car battery charger circuit with indication.

Applications of Car Battery Charger Circuit:Ĭar Battery Charger Circuit Working Principle:.

Car Battery Charger Circuit Working Principle:.

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