Automatic Battery Charger Circuit for 12V & 6V Battery


In this electronics project, I have explained how to make automatic battery charger circuit for any battery on the zero PCB. You can easily make this auto cut off charger circuit for charging a 12V battery or a 6V battery.

Auto cut off Battery Charger cover pic

First, you have to set the cut-off voltage, then you can supply 220V or 110V AC supply at the input and connect the 12V battery at the output.

The charging will automatically stop when the voltage across the battery crosses the preset cut-off voltage.

Circuit of Automatic Battery Charger

Automatic battery charger circuit

The circuit is very simple, You can easily make this project with some basic electronics components.

PCB Layout for Automatic Charger Circuit

PCB Layout of Automatic battery charger

Download the PCB layout, then print it on an A4 page. Please check the PCB size while printing, it should be the same as mentioned.

Required Components:

  1. 1k Resistor 1/4 watt (2no)
  2. 10k Potentiometer (1no)
  3. 10k Resistor 1/4 watt (1no)
  4. 10uF 35V Capacitor (1no)
  5. 1000uF 35V Capacitor (1no)
  6. 1N4007 Diode (1no)
  7. 1N5408 Diodes (5no)
  8. LED 1.5V (2no)
  9. BC547 NPN Transistor (1no)
  10. 12V SPDT Relay (for 6V use 5V relay)
  11. Connectors
  12. 15V 2A Step-down Transformer
  13. Zero PCB or Cardboard

Tutorial Video for Auto Cut-Off Charger

In the tutorial video, I have shown all the steps to make the Auto Cut-Off Battery charger circuit. So please watch the video for a better understanding.

How to Make the Automatic Battery Charger PCB

Steps for making the Automatic Battery Charger circuit on PCB

  1. Print the PCB Layout and stick it on Acrylic sheet or cardboard

    Making PCB for Automatic charger

  2. Drill the holes for the components as shown on Layout

    Auto cut-off charger PCB

  3. Connect all the components as shown on the layout

    Connect all the components

  4. Solder those Components as shown in the circuit

    Soldering the components

  5. Now, the Auto Cut-Off Charger PCB is ready

    Auto Cut-Off Charger PCB

Setting the Cut-Off Voltage

Setting the Cut-Off voltage

Now, to set the cut-off voltage, you have to connect a variable DC power supply at the DC input and connect a multimeter (voltmeter) at the battery side as shown.

For example, to set the cut-off voltage at 13V, you have to give 13V at DC input.

Then rotate the potentiometer until the red LED turns on.

After setting the cut-off voltage disconnect the variable DC supply and connect the step-down transformer at the AC input, as shown in the circuit diagram.

Please take proper safety precaution while working with 220V or 110V supply.

Finally, Auto Cut-Off Battery Charger is ready

Auto cut off Battery Charger

Connect a Lead Acid Battery at the Battery side (as per the circuit.)

Then give the 220V or 110V supply, the green LED will turn on, which indicates the battery is charging.

When the voltage across the battery cross the cut-off voltage, the relay will turn off and the battery will be disconnected from the supply.

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