This is a simple circuit of 12V rechargeable smart battery charger circuit. You can use this best battery charger circuit as car battery chargers, Inverter battery charger, Emergency battery charger etc. Automatic indicator alarm circuit is also comes along with this battery charger schematic. The main advantage of this indicator is that a buzzer informs us when the battery needs recharge. This circuit schematic definitely helps for your daily life battery charging applications. 

Circuit diagram of battery charger

Click on the image for enlarged view

Components required

1. Transformer (230V to 15V or 110V t0 15V)

2. Bridge rectifier (1N4007 x 4)

3. Capacitor (470µF, 50V)

4. Voltage regulator IC 7815

5. 12V rechargeable battery

6. Diode (1N4148)

7. LED Zener diode 9V

8. Transistor (BC547 x 2)

9. Resistors (10kΩ, 1.5kΩ, 100kΩ Each ¼ Watt)

10. Buzzer (12V)

Working of battery charger circuit

The charging circuit is build around voltage regulator IC 7815 and

two transistors BC 548.

The main supply 230V or 110V is step down using a step down

transformer, and then it is rectifiered and filtered out.

That DC voltage is fed to the voltage regulator IC 7815; the output

will be regulated 15V.

12 volt rechargeable battery is connected at the output of voltage

regulator and it charges when main power is available.

This circuit indicates the charging status that is the LED1 is glows

when the battery charged (Above 10.5V).

When battery voltage goes below a particular value LED1 stops

glowing and the buzzer produces sound indicating that the battery

has been discharged and it needs recharge.

Pin out of 7815, Diode, BC547, LED

BC 547 Transistor

Diode  

Zener Diode

Light Emitting Diode (LED)