Battery Charger with Overcharge Protection Circuit



Hi everybody,
Now I am here with a Automatic Battery Charger circuit having overcharge protection feature. In one of my previous post, we were discussed about a battery charger circuit. For that, the battery gets continously charged, and this overcharging affects the performance of the battery seriously. Today I am with a solution for that, as usual the circuit is simple to wire up, it consists only a few components and you can make this at your home itself. This circuit eliminates the battery draining due to overcharge, because the charger turnoff after the charging is made completed.





COMPONENTS REQUIRED

Transformer
9V,500mA
1
Diodes
1N4007
5
IC
LM317
1
Transistor
BC548
1
Zener Diode
6.2V, 0.5W
1
Resistors
2.2K (Variable)
1

1K
1

180
1

4.7
1

1.2K
1
Capacitors
1000uF, 25V
1
Battery
6V, 4.5Ah
1
LED

1


CIRCUIT  DIAGRAM

simple circuit



WORKING PRINCIPLE


The circuit is powered by 230V, 50Hz A.C supply. The high voltage supply is stepdowned using a suitable transformer to 9V and this alternating voltage is fed to a rectifier followed by a filter. The rectification is made possible using four diodes (1N4007), by employing the switching action of diodes. The elimination of ripples is done using a high valued capacitor. After rectification and filtering process we get a direct current, which is further stabilized using a voltage regulator IC LM317. The output from regulator is used to charge the 6V battery.
LM317








Once the battery is completely charged (ie; Voltage across the battery is 6V) the zener diode gets in forward biased and it starts conduction, this gives a positive voltage to the base terminal of BC548(NPN Transistor) which in turn makes it ON.


This ceases the charging of battery, because the output from IC is directly connected to the ground or negative potential through the forward biased transistor


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11 comments:

  1. Hi,
    Thank you very much for this Great Circuit Diagram. I like this one very much and want to make this circuit. I already Brought almost all parts but I cant understand how do I connect The IC "LM317" (Actually I didn't fund this IC instead of this I bought "LM317T" will this work properly?) and The Transistor
    BC548. Actually I am new in Electronics, Please help me build this circuit.

    Actually I need specific instruction on how to connect the IC and the Transistor, Which pin connect where...?

    I am really awaiting for your response, I already have parts, after getting suggestions I will connect the parts with a Perfboard.

    Thank you in advanced.

    Regards,
    MD

    ReplyDelete
    Replies
    1. I am glad that you like this circuit. I will definitely help you on making this one. LM317T and LM317 are same, which is a Linear technology based voltage regulator IC. The pin diagram of the IC is also shown above. Click on the circuit diagram to open it.

      If you have anymore doubts, comment it below :)

      Delete
  2. HI,
    Thank you for your very valuable information. Finally I built this circuit and everything is working perfectly but unfortunately the (Circuit) output voltage is avg 5 volt (its show 6 volt for few second i every minute).

    I think we need 7.0 - 7.5 volt to charge the battery fully in a certified way,,,

    Please help me fix this error/issue.
    See the below image for more understanding:
    http://s17.postimg.org/hp0swksr3/2013_07_15_04_51_03.jpg

    For any reference the voltage info below:
    You know the output current is 5 volt or 5.5 volt at the same time my main face voltage was 250 volt and the transformer (which power the circuit) voltage was around 7.5 or 8.

    I am awaiting to hear from you.

    Any help will be much appreciated.
    Thank you

    ReplyDelete
    Replies
    1. I Think Your stepdown transformer delivers an output voltage of only about 7V and this voltage is further reduced by the drop in rectifier diodes and voltage regulator IC. Thats why you get an output of 5V.

      Delete
  3. Hi,
    Thank you,
    Can you please give me a way to fix this... You know I need 7 volt on output. I not only made this circuit but also bought 3 battery which is not cheap. So, please tell me how do I fix this problem to get 7 volt and desire AMP on output. and also please how much amp shout there on the output to get battery charged correctly ?

    I need your help immediately otherwise my money/battery's will be damaged without charge...

    I made the circuit using the same parts mention on your diagram and please tell me what I have to do now.

    Thank you very much


    ReplyDelete
  4. HI,
    I connected about 18 volt (.6 AMP) on to power the circuit but No luck... I seen the same 5 volt but as usual blinks to 6 volt some times.

    please tell me which parts to change to fix this/ to get desired 7.5 volt ??

    I am awaiting for your news.
    Thank you in advanced

    ReplyDelete
    Replies
    1. This circuit is designed for charging 6V
      battery, for that 7V is enough. Does the
      output voltage rises while adjusting 2.2K
      pot.

      Delete
  5. Give me your Mail ID, we will contact you...

    ReplyDelete
  6. Thank you,

    The voltage is not rising while adjusting 2.2k pot. but its possible to low down the voltage by adjusting the pot.

    chockhong1@gmail.com

    is my mail. I will be very happy if you help me.

    -
    MD

    ReplyDelete
  7. Thanks for the tutorial...Are you using 1/2 resistor and the 4.7 resistor is it 4.7k

    ReplyDelete
  8. i have also the same doubt the 4.7 resistor is 4.7k ...

    ReplyDelete