Battery Charger Circuit with 4 LED Indicator

A universal current controlled automatic battery charger circuit with 4 LED indicators can be learned in the following post. The design also includes a 4 level charging status indicator using LEDs. The circuit was requested by Mr. Dendy.

The Request 

To Mr. Swagatam Majumdar :

I would like to ask and look forward to you to be made Automatic cellphone charger circuit 5 Volt and Automatic Lead Acid Battery Charger Circuit 12 V (in the schematic circuit and the first transformer CT) automatic / cut off by using a battery indicator and

LED lights red as an indicator were charging (Charging On Indicator) using IC LM 324, and

LM 317 and a full battery using a green LED and breaking electrical current when the battery is full.

For cellphone charger circuit 5 Volt I want to have levels of the following indicators:

0-25% battery is in the charger using a red LED.25-50% using a blue LED (red LED goes out)55-75% using a yellow LED (LED red, blue outages)75-100% using a green LED (LED red, blue, yellow outages).next to Lead Acid Battery Charger Circuit 12 V I want to use the 5 LED lights as follows:0-25% using a red LED25-50% using orange LED (red LED goes out)50-75% using a yellow LED (LED red, orange outages)75-100% using a blue LED (Led red, orange, yellow outages)more than 100% using the green LED (LED red, orange, yellow, blue outages).

I hope you, the components are common and accessible and made a circuit schematic above as soon as possible because I really need schematics details.

I hope you will help me to find a better solution. Thank you.

regards
Dendy

The Design 

The requested battery charger circuit with 4 LED indicators make use of  4 level status indicator and can be witnessed below. 

The TIP122 controls over-discharge of the battery while the TIP127 ensures an instant supply cut-of for the battery, whenever an overcharge limit is reached for the battery.

The SPDT switch can be used to select the battery charging either from a mains adapter or from a renewable energy source such as a solar panel.

Universal Battery Charger Circuit with 4 LED Indicator

36 Replies to “Battery Charger Circuit with 4 LED Indicator”

    1. Swagatam Post author

      Vijay, pin14 is not connected to ground, it is connected with the green LED. the ground is meant for the red LED illumination, if it's removed red LED will not respond…so it's not related to the opamp functioning..

      Reply
  1. VIJAY AJ

    Thanks for your reply sir. I did a circuit with small modification on your above circuit. From LM 324 I have used only three opamps instead of using 4 opamp. I used the first opamp for deep discharge protection as u mentioned in your circuit. Next I use my second opamp only for full voltage indication I just connect the second opamp to ground through resistor and led so that I get full charge indication. In my third opamp I just invert the inverting and non inverting terminal of an opamp so that opamp produce high output at preset is low and it produce high when preset passes over the reference…. Output from the third opamp is given to tip122 transistor that I have used instead of tip 127 but I connect the tip 122 in negative polarity as same as low voltage cut off. Everything is working fine but full load cutoff by third opamp is not disconnecting the tip 122 which is used in the battery side battery is still charging.i am using 12vbattery. I know some basic concepts please help me sir

    Reply
    1. Swagatam Post author

      Vijay, connect an LED in series with the TIP122 base and see what response it's giving, this will clarify the situation regarding how the opamp may be switching the transistor….or regarding any other issues.

      Reply
    2. VIJAY AJ

      Sorry sir for making you to confuse. I am using tip 122 in full load cutoff at negative terminal. I connected a led series to the base of tip 122 from opamp output. When I adjust my preset opamp become high this make me to fell that opamp is working well. I noticed following points during the operation…

      At first when I switch off the input power supply led in a base of tip122 blinks only an opamp produce high output

      When I turned on my power supply the led is illuminating even my opamp produces an low output. What is the reason for this sir????

      Reply
      1. Swagatam Post author

        Vijay, when you say full load cut off do you mean to say "battery full charge cut-off"?

        an NPN will not work optimally if used in place of the TIP127….I assume you have connected the emitter towards the battery positive and the collector towards the LM317??

        Reply
    3. VIJAY AJ

      No sir I know the difference between tip 122 and tip 127.I connected my tip 122oon negative terminal the emitter of a tip 122 is in LM 317 side and a collector is in battery side… Sir in my circuit I use transformer(12v) with parallel capacitor instead of lm317 to get a constant voltage . please help me sjr I think it is only a minor fault in my circuit I can't able to identify it correctly…

      Reply
      1. Swagatam Post author

        Vijay, did you do any changes in the above diagram?

        If yes then you may have to provide me the drawing of it, only then I would be able to troubleshoot it.

        Reply
      1. Swagatam Post author

        Vijay, I have seen it, it looks OK to me. actually a similar problem is happening with another circuit:

        http://www.homemade-circuits.com/2014/04/48v-solar-battery-charger-circuit-with.html

        I think the problem could be arising because the transformer negative is "more negative" than the battery negative, which is preventing the switch OFF of the left side TIP122 in your diagram.

        did you try connecting a zener with pin8?

        connect a 4.7V zener at pin8 and check the response….cathode will go to pin8

        and also connect a 1K between base and emitter of the left mosfet

        Reply
    4. VIJAY AJ

      OK sir I will try it in today..sir voltage across the capacitor near to transformer is 14.5v shall I use LM 317 to regulate the voltage to 12.8v. I have a doubt sir LM 317 can handle the current flows in 12v. 7.5ah battery??? Because LM 317 can handle up to 1amp maximum right???weather 7.5ah battery absorb more than one amp current at any situation???

      Reply
      1. Swagatam Post author

        Vijay,
        14.5V is the right voltage for charging a 12V battery so it's OK.

        317 is internally protected against overload and overcurent so it will never allow above 1.5 amps to pass through it and will control this level automatically.

        but make sure to add a large heatsink to it for allowing an optimal performance from it.

        Reply
    5. VIJAY AJ

      Sit its not working do u have any idea to solve this problem?? I think using separate driver circuit for the operation of tip122 will solve this problem am I right sir??? If u have any driver circuit suggest me sir I will try it today

      Reply
      1. Swagatam Post author

        OK do it in this way:

        1) first swap the inputs of the opamp, meaning now (+) will go to the preset just like the other opamps.

        2) connect a BC547 with this opamp, base to opamp out via a 10k, collector to positive rail via a 10K, emitter TO THE NEGATIVE OF THE POWER SUPPLY NOT BATTERY.
        and base of TIP122 to the collector of this BC547

        this should do the job.

        Reply
    6. VIJAY AJ

      Sir.The circuit is working when I connect a led series with an opamp output that means anode is connected to opamp output and cathode of a led is connected to base of tip122.when my opamp output is low battery is not charging and it charging when my opamp output is high. My question how it works well by connecting a led to the base of tip122 .I didn't understand the operation but its work well sir…

      Reply
      1. Swagatam Post author

        Vijay, I had suggested the same LED idea initially but you said it wasn't working using a base LED…
        and then I advised a zener at the base for the very same reason and you said it didn't work either, so how come it's working now?

        The idea behind using an LED or zener buffer is to stop whatever biasing voltage the TIP122 might be receiving from the opamp while its output is in the switched OFF condition.

        Reply
    7. VIJAY AJ

      Yes sir this is your idea. I don't know why it didn't work on first time but it works very well sir. I am continuesly monitoring my battery voltage about 5hrs it never changed thanks you very much sir I can't do this successfully without your help sir.thank you very much sir I learned one new concept from you today….

      Reply
    8. VIJAY AJ

      Sir using led series to the opamp works well for improving my knowledge I have a doubt sir what I need to do next if led fails at this situation. Do u have any other suggestion to overcome this problem. If u know any concept share with me sir it will help me on future… Sir one more question… Shall I replace led with someother devices because led illuminating in this case I didn't need a illuminating if there is any other idea other than using led share with me sir otherwise I use a led in the circuit. Thanks for your support sir

      Reply
      1. Swagatam Post author

        you can try connecting a 1k preset between base and emitter of TP122 and adjust it until the transistor just switches OFF, (when opamp output is at zero volts)

        Reply
  2. VIJAY AJ

    Sir I tried this same circuit I don't know why its not functioning full load cutoff but deep discharge is working well…even my opamp output is high battery is still charging .suggest some idea for me sir. If there is any circuit to test tip 127 suggest me I wiwill try that too

    Reply
    1. Swagatam Post author

      Vijay, you said you had done some modifications, so i am confused whether you did you build it exactly as above or modified something in it?

      and what is "full load"? do you mean full charge?

      TIP127 will switch OFF only when battery voltage becomes equal to its emitter voltage

      and one more thing the TIP127 will rapidly switch ON/OFF at the threshold because there's no hysteresis control in the design.

      do one thing add a 1M resistor across pin14 and pin12…this will allow you to witness the TIP127 switch OFF for some moment clearly.

      Reply
  3. nanigopal mahata

    sir , i can't understand anything from above comment…. please tell me what will be changed for 12v 7.2Amh battery… and what is the adapter means.. can i use there a 12-0-12 1amp transformer with bridge rectifier? pls send me all parts list, and also the solar plate ratting

    Reply
    1. Swagatam Post author

      nanigopal, you can build the circuit exactly as shown in the diagram…set the respective presets and pots as per the specifications of the battery….the solar panel can be a 18V, 1amp panel

      yes a 12-0-12 trafo with bridge and filter cap can be used for the adapter…..use the 0-12V tap…do not use the 12-12 taps

      Reply

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