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  • This is the simple and easy way to tap current from a Motor Bike battery to charge the Mobile Phone. Most of the Mobile Phone battery pack has three 1.2 volt cells making the voltage to 3.6 volts. For fast charging of the battery pack, each cell requires more than 1.2 volts and sufficient current. This circuit can deliver 5 volts at 300 mA to charge the battery quickly. The circuit is Voltage and Current regulated and with Polarity and Surge protection components.

    Mobile Charger using Bike Battery Circuit Schematic

    The circuit uses a Positive Voltage regulator IC 7805 to give 5 volt regulated output. The components around IC1 are meant for protecting the IC so as to give smooth output power. Zener diode ZD act as the Input Surge protecting diode. It provides 7.2 volts to the input of the regulator IC from the 12 volt bike battery. Diode D1 is the Output Surge and Input Short protecting diode.

    When a surge voltage exceeding maximum voltage rating of the regulator is applied to the input or when a voltage in excess of the input voltage is applied to the output, the regulator will be destroyed. If the input terminal shorts with the ground, the output voltage increases above the input voltage(ground potential)and the charge in the capacitor connected to the output flows into the input side which is also fatal to the regulator. Both these situations can be avoided by using the Zener at the input and the diode D1 across the regulator. Capacitor C1 and C2 provide stability to the regulator and these should be soldered close to the legs of the regulator. Capacitor C3 act as a buffer to give constant voltage in the output.
    7805 Datasheet

    7805 IC can tolerate maximum 35 volts and its current rating is 1 Amps maximum. Resistor R1 restricts the charging current to around 330 mA as per the Ohms law. Even if the current is low, charging process will not be affected. Slow charging with 80 to 100 mA current is generally advised. But in case of an emergency, quick charging can be done with high current

    Assemble the circuit on a Perfboard and enclose in a small case that can be fitted near the Bike battery. Use suitable pins to connect with the Mobile phone. Charging current can be tapped from the battery using Alligator Clips. Before using the circuit, double check the connections especially the polarity of connectors and measure output voltage and current using a Digital Multi Meter. The same circuit can be used for charging Mobile battery from 12 volt Car battery or from a 12 volt Solar panel.

    IC 7805 Pin connection and Alligator Clips

    attentionThe author D Mohankumar is not an active member anymore. Please take into consideration that the presented information might not be correct.
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    42 Responses to "Cellphone Charger Using Bike Battery"

    1. J M Fahey says: on March 24, 2010 at 1:14 am

      This circuit has obviously never been built.
      The 7.2V Zener diode wil explode the very second it is connected to a 12V battery.

    2. D Mohankumar D.Mohankumar says: on March 24, 2010 at 2:11 am

      See the Precautions on Applications of 7805 in the data sheet provided along with the circuit

      • resistors 15R 1W AND 100R 1W drops the output current below 60mA. ie insufficient current for proper charging. change the resistors values. i think maximum current drawing without resistor is 800mA and will reduce with charging. without resistor also good

    3. Dear sir
      I have worked with you circuit.but i did’t get proper output. i want to know about following things in your circuit .why you r using zener diode & 100 ohm resistor & 15 ohm resistor.do u have any other circuit for design motor bike charger

    4. nouman nayyer says: on July 6, 2010 at 10:15 am

      dear
      i want to ask u some thing
      mobile phone needs 3.7 volts to charge.
      but 78l05 regulates 5 volts???

      • Swapnil says: on June 28, 2012 at 6:25 am

        Actually, mobile phones can be charged in the range of DC 5 – 12 V range. But if the battery is constantly charged at higher voltages, it’s life will be reduced.

        The 3.7 V specification is for prolonging the battery life. However, we have to keep the phone charging for a long amount of time with this voltage. So, the IC 7805 is used.

    5. sir did u have charger prepared from smoke from the bike

    6. sir is there any mini project ckt on mobile charger

    7. electronics baics

    8. the Zener diode ZD start heating when we apply 12v to the circuit.. there must be some change in the circuit…

    9. Sir, what if the output current is just a few mA in the given circuit and we have to increase it upto 300mA ?

    10. could send me the project report of this

      • Adnan Rafiq says: on December 7, 2011 at 1:01 pm

        i am a electrical engineer.if you are a pakistani.then sent me text message.my phone number is +923327929262.i will contact you.

    11. this is waste circuit da kunju paya

    12. can I have a detailed working material for this project???if so send it….

    13. I was from Philippines,an electronics technology student.Thank YOU for this I will try to make it because our place was sometimes having a brown outs.

    14. sir,Is it tested?

    15. narayana behera says: on October 23, 2013 at 4:57 am

      sir pls tell me how can i get more current than 330mA for which mobile battery quickly charged

    16. narayana behera says: on October 23, 2013 at 5:00 am

      sir pls give me some ckts like cfl drive by using 6V battery via my email

    17. ravikiran says: on December 2, 2013 at 11:57 am

      sir it is succussfull but “IC7805″ is very tooomuch heatincress connected to mobile why sir ? plz reply via mailid……..

    18. samir pandya says: on June 25, 2014 at 10:55 am

      thenk’s sir

    19. Shamas ul haq toor says: on August 20, 2014 at 12:18 pm

      Aslam o alykum sir
      This is shamas from daska
      There is a problem with long time i can’t handle this problem.
      Sir if u help me i’ll thankfull to u for always.
      Sir.
      Mery pas 30amp ki 12 v ki acid bettry h mein us sy mobile b charge krna chahta hn or evo wingle usb b chalana chahta hm
      Koi aisa method btaen k bettry 12 volt convert kr k 5 volt ya usb port ko jitny volt chaheay wo mily.
      Sir yaqeen maneen 1500 rupy haram kr chuka hn abi koi method kam ni aaya.

    20. Dear sir,
      i try to this circuit but output current is insufficient.
      my mobile Moto G carry the current 500ma, but this ckt output is just 300ma only,
      my mobile indicating charger symbol but not increasing charging level. please give me a good result circuit.
      (note-this circuit also try to another model mobile phones ex.samsung galaxy Y& S3)
      Thank u

    21. 7805 is good regulator ic. In this circuit zener diode and resistor R1 is not necessary. Zener used to support IC. If avoid R1 help us make quick charge mobile phone. But never use this circuit regularly it reduce battery life. Because output current around 1amp.

    22. Nimesh Parmar says: on March 16, 2015 at 6:26 am

      I am new in circuit. Can you say what voltage would be for C1 and C2 Capacitor?

    23. karthick says: on May 4, 2015 at 11:00 am

      Sir Charing is not complete flactuation is created .so charge engaged and disengaged

    24. what is mean of 0.33 & 0.1 rating in capacitor

      is it means 330uF & 100uF ??

    25. Ravinder kumar shah says: on June 10, 2015 at 6:22 am

      Dear sir
      I have required 200 pulse bik mobile charge

    26. C.Mitra C.Mitra says: on July 1, 2015 at 1:22 pm

      Here is another example of a half cooked circuit designed by a novice. Let me point out the anomalies:-

      1) There is no need for a 100 ohm resistor and 7.2V zener diode in this circuit. We are using a 5 V regulator IC which can easily handle an input voltage of 12 V DC without any problems. The resistor and zener are going to unnecessarily waste precious power.

      2) Again there is no necessity for a 15 ohm resistor in the output to restrict the current. Mobile phones by default require 5.0 V DC for their charging circuitry, and restricting the output current is only going to prolong the charging time needlessly.

      Please edit the circuit so that it is more realistic. Adding more components does not make a circuit better.

      Thanks

      • Sir i have made this circuit but there is a issue. This circuit consumes so much power from battery. Due to this battery gets low, even during the time where no mobile is connected on output side of circuit

      • C.Mitra C.Mitra says: on July 2, 2015 at 8:56 pm

        Dera Neel,

        I hope you have read my post above (dated July 1, 2015) carefully? Just remove the 100 ohm resistor and the zener diode, because the zener diode is bleeding 48 mA of current continuously, which I think is draining your battery too fast. By the way, is the regulator IC getting hot?

    27. Dear sir,
      Yes it gets hot while connected but not so much hot.

    28. Sir i want to make a circuit which can open circuit by a single external signal. And will remains open even after when external signal is disconnected. Please give me suggestions which dc component can work as that.
      Circuit should remains close in normal conditions.

    29. C.Mitra C.Mitra says: on July 5, 2015 at 9:17 pm

      Hi Neel
      I don’t know what you mean by ” i want to make a circuit which can open circuit”. A circuit which can open a circuit? What circuit do you want to open? Please write your requirements in clear understandable English.
      Thanks

      • Sir
        Plz suggest any component which can use as a switching device.
        Basic requirement is the component can work as closed switch in normal conditions, and it can be open by a single electric signal and will remain open even after signal is disconnected.

    30. C.Mitra C.Mitra says: on July 6, 2015 at 6:01 pm

      Neel
      There is no such single component which can behave in the manner that you want. It seems what you need is a relay which is normally closed, but on applying a voltage to the associated circuit, it opens. But you want it to remain open even after the signal is removed. But then how do you want it to close again? Does it need to be closed under certain conditions? Please clarify.

    31. Sir
      I want to use another signal to reclose the circuit.
      In a simple manner the circuit will be operate remotely in which it can be open or close by two different signals.
      If it is possible then plz give your mail id or another contact details.

    32. I need help says: on July 23, 2015 at 2:52 am

      Greetings,

      I need to know that is that any way i can get a output of around 5v and 1~2A from a 12vDc 0.5A battery?

      If yes then some idea how it can be done?

      Thanks in àdvance.

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