Simple battery charger circuit.

Description .

Here is the circuit diagram of a simple and straight forward 12 V battery charger circuit with diagram. This circuit can be used to charge all type of 12V rechargeable batteries including car batteries. The circuit is nothing but a 12V DC power supply with an ammeter for monitoring the charging current. The two diodes forms a centre tapped full wave rectifier. The capacitor filters the rectifier output to produce a clean 12V output.

Circuit diagram with Parts list. 



  • At initial stages of charging the ammeter will read about 1 to 3 amperes.
  • As the battery is slowly charged the current slowly decreases.
  • When the battery is fully charged the ammeter reading will be zero.
  • Always be careful to connect the charger to the battery in correct polarity. Positive to positive and negative to negative.

Show Comments

22 thoughts on “Simple battery charger circuit.

  1. wacks

    hi nice one! I build that one but i think the power of the battery go back to capacitor and i plan to put some diod in possitive side. do you think its ok?

  2. goerge

    what changes if i use 12 amperes transformer? can 3 amp diodes will be replace to 1n4007, and how to modefied it to make auto cut off if the battery is fully charge.thanks.

  3. Qaisar Azeemi

    thank you very much Seetharaman. and what do you think about the chargers that are made using regulators like LM317. is this ckt also have the current limit capability of transformer.

    i wana design a powersupply with a battrey backup. i need a charger to charge the battery and i am using regulator charger using LM317. will it also limit the current or not. also is it good to use such a charger with online/battery back up power supplies?

  4. Anthony

    Hi friend,I want to make a stand alone 6v bike battery charger cum DC to AC-5A circuit.Could you please help me?

  5. Seetharaman

    Hi Qaisar the maximum current is limited by the transformer capability. You may add a 2.2 ohms in positive line,(use 2nos 6A1 rectifiers) with the discharged battery, the charging current will be to a maximum of 2 to 2.5 amps. The voltage output will be around 16 volts from the charger(24volt?). since this is a simple circuit once the charging current falls down to around 0.2amps disconnect the battery.

  6. Qaisar Azeemi

    it is quite simple charging circuit. i am afraid it will damage the battery because no current control circuit is seem here to controle the current to the battery.
    secondly will a 12V lead acid or sealed lead acid battery is capable to tolerate 25V on its input.
    hope you will guide me.

  7. Ovie Peter

    I sincerly need your help.I manufactured a fuelless engine that work with Battery only.But i need a Battery charger that can be charging the Battery while the engine is working.Please,what can i do?

  8. aljhun

    hello….i want to asked how 2 make 12vdc battery charger or rectifier to my 35 0 35 centertop transformer?….dn what resistor will be used?..thanks

  9. Richard Olszowy

    Have you a modified Circuit to show the placement and value of the resistor mentioned by the person “Leandro” ?

    Also I am wanting to also build a 6 volt charger, for a 6v Gell type of battery, similar in size to a motor bike battery.

    Can you tell me the Different Transformer and Resistor Value, and whether I should fit a Zenner in the circuit ???

  10. shashidhar

    Hi friend
    Can it be used for charging of battery cells? If yes, what should be the specifications of that battery cell?

  11. Leandro

    Leandro:excuse-me friend,would you help me with a doubt please? i would be glad to know if this circuit has a high eficience or if it waste a considerable part of the energy it receives. And i wonder to know if it isnt dangerous to make this circuit without any resistence like in this diagram.

    Reply: The two factors you said are correct.The circuit is not a highly efficient one.Secondly it should be better to place a resistance for limiting the charging current.But I designed this circuit to be simplest as possible.Thats why I deliberately ignored the factors you said.But there is nothing that harmful in using the circuit.It will work quite decently.But you cannot leave the circuit alone.The charging current has to be frequently monitored from the meter.And you have to disconnect the charger manually when the battery is fully charged.
    A better circuit with all factors pointed by you will be soon here.I am working on it.Thanks for the comment.


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