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Simple Solar Battery Charger Circuit

The post explains a simple solar battery charger circuit using the IC LM338 which can be built and installed by even a layman for achieving the intended results.

Solar Panel Installation

Solar panels are not new to us and today it's being employed extensively in all sectors. The main property of this device to convert solar energy to electrical energy has made it very popular and now it's being strongly considered as the future solution for all electrical power crisis or shortages.

Solar energy may be used directly for powering an electrical equipment or simply stored in an appropriate storage device for later use.

Normally there's only one efficient way of storing electrical power, and it's by using rechargeable batteries.

Rechargeable batteries are probably the best and the most efficient way of collecting or storing electrical energy for later usage.

The energy from a solar cell or a solar panel can also be effectively stored so that it can be used as per ones own preference, normally after the sun has set or when it's dark and when the stored power becomes much needed for operating the lights.

Though it might look quite simple, charging a battery from a solar panel is never easy, because of two reasons:

The voltage from a solar panel can vary hugely, depending upon the incident sun rays, and

The current also varies due to the same above reasons.

The above two reason can make the charging parameters of a typical rechargeable battery very unpredictable and dangerous.

Using LM338 as Solar Controller

But thanks to the modern highly versatile chips like the LM 338 and LM 317, which can handle the above situations very effectively, making the charging process of all rechargeable batteries through a solar panel very safe and desirable.

The circuit of a simple LM338 solar battery charger is shown below, using the IC LM338:

simple solar battery charger using IC LM338


The circuit diagram shows a simple set up using the IC LM 338 which has been configured in its standard regulated power supply mode.

Using a Current Control Feature


The specialty of the design is that it incorporates a current control feature also.

It means that, if the current tends to increase at the input, which might normally take place when the sun ray intensity increases proportionately, the voltage of the charger drops proportionately, pulling down the current back to the specified rating.

As we can see in the diagram, the collector/emitter of the transistor BC547 is connected across the ADJ and the ground, it becomes responsible for initiating the current control actions.

As the input current rises, the battery starts drawing more current, this build up a voltage across R3 which is translated into a corresponding base drive for the transistor.

The transistor conducts and corrects the voltage via the C LM338, so that the current rate gets adjusted as per the safe requirements of the battery.

Current Limit Formula:


R3 may be calculated with the following formula

R3 = 0.7/ Max Current Limit

PCB Design for the above explained simple solar battery charger circuit is given below:



The meter and the input diode are not included in the PCB.

Need Help? Please leave a comment, I'll get back soon with a reply!




Comments

  1. What is the modifications in the circuit if i want to charge 24 v battery with 12 v of solar panel input.

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  2. that's not possible with this circuit.

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  3. sir,
    i want to charge a 12 volt 5 amp battery using this circiut in your blog..what would be the specification of the solar pannel..plz help.

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  4. You can use a 18V/1amp solar panel for it.

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  5. sir,
    I have to drive robot which require 12 v,1.5 amp to operate .So,please help me to decide which solar panel and rechargeable battery i have to use.

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  6. battery can be a 12V 7.5ah and the solar panel = 14v, 1amp

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  7. sir,
    I want to design a solar battery charger,all components should be SMD type and my aim is to reduce PCB size as much as possible...pls help me...

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  8. Vipu, what specifications do you want for the solar charger circuit?

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  9. sir, what is the charging current of 12v 7Ah battery? what is the diode use in here?and what is the watt of resistor to be use?..thanks

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  10. Erns, R4 is not needed, you can remove it.
    the ideal charging current of a 12V 7ah battery is around 1amp.
    the diode is for preventing accidental polarity reverse conditions at the input.

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  11. still we are not finalised,but mostly it wiil be 5V/6V battery charger....but i need a circuit for my reference,can u send me?....pleaseee

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  12. should it be automatic, or manual?

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  13. you can try the second circuit from the following link, except LM317 all other parts could be SMD

    https://homemade-circuits.com/2012/07/make-6v-4ah-automatic-battery-charger.html

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  14. hiii...
    I have 1 more doubt,how to connect a temperature sensor TMP100 with a CC2541 IC.Should i use I2C pin or any other digital I/O pin???? thanks

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  15. I'll have to do some research on it before suggesting.....

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  16. Sir me bhanu can u plese tell me how to calculate charging current easily....
    You have given a formula i.e 0.6/Charging current
    Can i use 0.6/ battery Ah or i will take 1/10th of battery Ah

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  17. 0.6 should divided by 1/10th of battery AH.

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  18. Thanks sir i have assembled all the components except this resistor.... taking your suggestion i will progress the circuit and tell you about the output ....
    Sir do you have a of DC 12v to 18v or 24v DC converter circuit i am not not getting this in your site...can you please help me...once again thank u ...

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  19. Bhanu, you can try the following converter circuit:

    https://homemade-circuits.com/2012/09/led-emergency-light-circuit-using-boost.html

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  20. hii sir,
    Is there any single chip IC for dust sensor and sound sensor??? If no please suggest me a simple circuit... thanks

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  21. hi Vipu, sound can be sensed by a mic, I am not so sure about dust detection.

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  22. Sir, i have 70Ah 12volt battary and i'm about to buy 100Ah solar panel to charge it. there need to be solar charging system(circuit)? could i connect battary directlly from solar panel for charging? it will harmfull for battary?

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  23. Dev, solar panel current is not rated with AH, its rated with amps....a controller can be avoided by selecting a correctly rated solar panel for the battery.

    for a 12V 70ah battery use a 18 V, 10amp solar panel....18v is the peak rating of the panel and 10amp is the short circuit current of the panel

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  24. have a good day sir!!!
    plz help me about my question that, is it possible to charge 12 volt 1.5A battery from 6 volt 250 mA solar panel?????

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  25. good day Tejas,

    No that's not possible, the voltage should be minimum 14 V

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  26. thank you for your reply...
    but sir if i will place a boost converter in between solar panel and battery.....is it true??

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  27. ....for that your solar panel supply should be rated to generate at least 1amp output, 250mA will not do.

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  28. ok... so according to you i should connect two 6 volt, 250 ma panels in series... then i will get 12volt 250ma.... am i true sir??

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  29. actually i want to make charging my 24 volt 1.5 Ah battery to supply 24 volt, 600 mA STEPPER MOTOR.....
    is this possible from 12 volt 250 mA solar panel using 12-24 volt boost converter???

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  30. Hi sir,
    I realised the circuit of this article but I can manage only the voltage at the output with the potentiometer, not the current. What could it be wrong? I didn't put the R4 and I switched the multimeter as ammeter and connected it in series the output of circuit with the battery.

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  31. yes that will do but the voltage will need to be at least 14V to initiate the charging....

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  32. No it won't, it's the same situation as previously explained...

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  33. Hi Daniele

    R4 is not required anyway, so the current limit will still work for you depending upon the selection of R3

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  34. ...the pot is only for varying the voltage not current, current can be managed by altering R3 as explained in the article.

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  35. Thanks, I really appreciate your help, the circuit works, finally! ;) I have just one more question: there is any ways to evaluate the charging current? I have two batteries in parallel, one is 10Ah e another one 4.5Ah. The solar panel produce 1,7A and the R3 is 0.47ohm. I guess I made the correct calculation but I would check the real current that pass on the circuit. Any suggestions? Thanks in advance for any answer :)

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  36. Thanks Daniele,

    Usually it's AH/10 for lead acid batteries and AH/1 for Li-ion batts, but if you have two batts in parallel with different AH rating in that in case you may have incorporate separate current limiting circuits for each batts.

    You may have to make two of the above circuits, and calculate R3 separately in order to feed the respective batts...the ground will be common for both the circuits.

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  37. Hi sir
    I wanna ask if i can use this circuit to charge a 12v 40W lead acid battery ti powerup an LED lamp during the night. I'm planning to use this for a streetlight.

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  38. Hi Nine, did you mean a 40 AH battery? Yes you can use the above circuit for charging a 40AH batt, make sure to put the IC LM338 on an adequately large heatsink

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  39. sir can you explain the role of each component in the circuit? i wanna understand how each of them function.. and how did you come up with the computation R3=0.7/chg. current? thank you so much sir!

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  40. The upper resistors are as per the IC datasheet...the BC547 is responsible for grounding ADJ pin of the IC and disabling it when an over current is sensed, and this happens when the potential across R3 exceeds 0.7V which is the switch ON (saturation) voltage of the transistor

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  41. sir what is the maximum Ah that this circuit can handle? and can you teach me how to add an overcharge protection circuit to this one because i need the circuit to automatically stop the charging when battery is full.. thank you

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  42. Nine, the LM338 IC used in the circuit can handle up to a 50 AH battery for charging.

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  43. correct me if I'm wrong sir, but you're assuming that the battery is rated @10 hr. I will be using a battery that will be rated @20 hr, so i can use a maximum of 100Ah because 100/20= 5A, which is the maximum output current of LM338..

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  44. I don't know if a lead acid battery can be charged at AH/20 or C/20 rate, so I can't say much about this calculation...C/10 is considered as the minimum optimal range for charging lead acid batts.

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  45. ok sir i'll research more on that.. anyways can I use a 24V 50W panel to charge a 55Ah 22V battery, by the way the battery will supply a 12V 45W LED Lamp.. what's your opinion about this sir?

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  46. Nine, you will require a minimum 125 watt panel for charging the specified battery....50 watt will not do it satisfactorily.

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  47. sir if that's the case, can I still use the above circuit? by the way it's 12V 55ah battery

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  48. for a 12V battery a 50 watt panel can be used, but the panel peak voltage should not be above 15/16V for an optimal response,

    yes the above circuit will just fit in.

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  49. sir this is the current setup of the project..
    12V 50W solar panel to charge a 12V 40Ah lead acid battery, the load will be 12V 24W LED lamp
    what are your thoughts about these adjustments? and can the circuit above can charge a deep cycle battery? thank you so much sir for answering my questions

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  50. yes a 12V 50 watt panel can be used for charging a 12V 40AH deep cycle battery, but will require around 10 hours to get fully charged.

    a 12V panel during peak should be producing 15 to 16V, so according to me you can connect it directly with the battery through a 6A4 diode...the above circuit may not be required.

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  51. for the current rating of the solar panel (12V 50W), what do you suggest I use sir? a 12V 40Ah lead acid battery or a deep cycle battery?

    note: the battery should be able to supply enough power to the LED lamp for the whole night (12 hours at most). thank you sir

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  52. deep cycle batteries are also lead acid batteries, so you can use a 40AH lead acid battery for the said purpose.

    The mentioned 24W lamp can be operated for not more than 6/7 hours at stretch with a fully charged 40AH batt.

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  53. what do you suggest sir that I do to make it longer?

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  54. There's no way to increase the back up time, unless another battery in parallel is used.... but that will require upgrading the panel to 100 watts.

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  55. what if I used a battery of 45Ah or 50Ah?

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  56. yes will do but a 50 ah battery will need a higher wattage solar panel for fast charging, it will charge very slowly with the existing 50watt panel

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  57. how bout a 60- 80 watt panel?

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  58. Yes, you can try it out, might just work.

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  59. i'm determined to use your circuit so what should be the input voltage and current for lm338? and is there anyway to adjust the output current?

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  60. input voltage is 32 max, current doesn't matter it can be anything as long as volatge is within 32V.

    the max output current can be set anywhere from 0 to 5amps by selecting different values for R3 as per the calculations

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  61. Hello sir. I would like to use the above circuit to charge a 3.7V 1500mAh mobile phone battery, with a 12V 5W panel. Can you please let me know the changes needed to be done to the circuit?

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  62. Hello LNB, the above circuit may not be appropriate for your application, you can try out the following instead:

    https://homemade-circuits.com/2012/08/simplest-dc-cell-phone-charger-circuit.html

    Make sure to replace the 9V zener with a 4.7V 1 watt zener and connect the 3.7 cell across the outputs indicated with a charger pin.

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  63. Hello, sir. I would like to thank you for your reply, and for the alternate suggestion. I just wanted to ask, couldn't I adjust the pot P1 to get 5V (4.2V battery's fully charged state voltage + 0.7V diode forward drop), and select R3 to get 10% of my battery's mAh?

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  64. sir what is the specs for the two diodes?

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  65. Hello LNB, yes you may do it, please refer to the following article for the exact info

    https://homemade-circuits.com/2014/12/12v-dc-solid-state-relay-ssr-100-amps.html

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  66. for Li-ion batts, 1/10th AH charge rate is not critical...you may apply even upto 1C rate that's equal to the Li-ions AH rating...

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  67. twice of the charge rate in amps

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  68. Hello sir. So, for a 1500mAh battery, i can use a 1.5A charging curent rating safely, as long as i remove the battery immediately after charging?? The only limitation is from the solar panel, isn't it?

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  69. sir i'm having problems with the circuit.. I tried. to construct this circuit in smaller scale so I bought a 12V 10W solar panel to charge s 6V 4.5ah battery. I used lm317 and I eliminated the transistor part because I want to see the output voltage first. But then the output voltage i'm getting is only up to 1volt. I checked the output voltage from the solar panel alone and its 7V. sir what am I doing wrong here? I haven't tried to put the panel under sunlight because it is cloudy here so i'm just testing it under indoor light.

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  70. Nine,
    That's impossible unless you have done something wrong with the connections or have a faulty (duplicate) chip.

    You may refer to this article for a better view of the concept:

    https://homemade-circuits.com/2012/02/how-to-make-current-controlled-12-volt.html

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  71. it's okay sir.. I just tried to put the panel under outdoor light even if it's cloudy.. now i'm getting up to 12V from the circuit.. I guess it makes a huge difference when you're testing it indoor.. now the problem is the output voltage keeps changing whenever I move the panel from different locations.. I adjusted the circuit to produce 7V but it keeps changing when I move the panel.. I thought this circuit will produce constant voltage once I adjusted the potentiometer regardless of the varying input voltage from the panel.. sir what is wrong here?

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  72. Yes the IC must produce a perfectly constant voltage regardless of a changing input.

    Check and confirm the circuit first with a variable DC power supply and see the response.

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  73. sir what should be the minimum input voltage from the panel so I can constantly produce 7V from the circuit using lm317? and what should be the minimum input voltage from the panel so I can achieve 14V from the circuit once I used the lm338?

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  74. It should just 1V higher than the required output, meaning for 7V output the input could be 8V...and for 14V output it needs to be 15V minimum

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  75. then it makes sense when the output voltage changes because the input voltage gets lower from the solar panel.. sir do you have any more circuit that can produce constant output regardless of the changes in the input?

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  76. ....the output should be perfectly constant even if the input fluctuates widely but it should not be very close or lower than the intended load voltage

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  77. ok now I understand thank you sir.. anyways sir can I request for your insight on how to calculate the approriate battery and solar panel for our 12V 24W LED Lamp that should stay on for a whole night.. I just wanna have a concrete basis for picking the battery and panel..

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  78. you may refer to the following article for a detailed info:

    https://homemade-circuits.com/2013/05/how-to-calculate-and-match-solar-panel.html

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  79. sir i'm a bit confused.. i followed all the calculations and it said I need at least a solar panel of 30W and a battery of 20Ah.. but you said before for a 24W lamp I will need a panel of greater than 50W and a battery of more than 40Ah.. sir please explain thank you

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  80. you might have calculated wrongly....a simple way is to divide 30 by 12, it gives 2,5A, how can a 2.5A charge a 40AH battery within 6 hours, it would take about 18 hours at that rate.

    a 24 watt lamp will consume 24/12 = 2amps...so with a 40AH batt we get 40/2 = 20hours ideally but it would be just approx 12 hours practically

    so you will have to charge a 40AH battery fully for sustaining a 24watt lamp for about 12hours

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  81. hello again sir! i finally implemented the above circuit. I used a 100W solar panel to charge the 40Ah battery. First I used the battery to power the lamp and it dropped to 8V. I think the charging works fine because from 8V, the circuit was able to charge the battery to 13V. The problem now is that the battery is quickly draining, dropping to 8V after 2 hrs of supplying power to the 24W led lamp. The lamp still stays on but I think that should not happen to the battery dropping off too quickly. What would be the problem here?

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  82. Hello Nine, you must charge the battery up to 14.3V, for ensuring 90% charging....13v is not the optimal level for a 12V batt.

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  83. sir is that why the battery is dropping so quickly? also we also connected a regulator ic which is 7805 to bring down the voltage to 5V for our microcontroller, is 7805 also a factor why the battery is dropping? thank you sir

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  84. yes if the battery is not charged optimally, it will drop quickly, 7805 is not responsible for this at all.

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  85. also sir is it ok if I connected a dark sensor circuit parallel to the battery so the led lamp will automatically switch on at dusk? If yes, will it affect the charging process because the output current from the above circuit will be divided for the battery and sensor circuit?

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  86. yes it's possible, it won't affect the charging process since the current consumed by the system will be relatively smaller.

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  87. thank you sir.. so I will connect it in parallel then and remove the relay now

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  88. sir i'm still thinking if I should remove the relay in the circuit.. the setup now is that the relay serves as a switch for the sensor circuit, if the battery is in charging process the relay trips and the sensor is disconnected from the circuit so the charging current is divided to the battery amd relay.. if I do remove the relay the charging current will be divided to the battery and sensor circuit, however, the sensor circuit is composed of a voltage regulator, ATtiny mmicrocontroller, op amp, and a power mosfet for the LED.. I know the sensor circuit is quite large so it will really require a sufficient amount of current than the relay I think.. what would you do here sir?

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  89. Nine, the sensor circuit is not supposed to consume more than 5 to 7mA and the relay not more than 30mA....so it's your wish now whether to use the circuit or not as per the application needs.

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  90. sir do you know any current amplifier circuit that i can use because the output current from the circuit is very low, i recorded 200mA as the highest current that the circuit can supply so far which is not enought to fully charge the 40Ah battery. The panel is rated 100W and current peak is at 5.61A but it only supplies about 400mA input current to the LM338.

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  91. Nine, a current amplifier is out of question here....if your 100 watt panel is producing 400mA simply means it's faulty or something may be wrong with the connections....or if this happening after the LM338 IC stage would indicate a faulty or incorrectly wired LM338 IC....please check all these individually to confirm the results.

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  92. hi sir i sent an email,need your help for my project,very very tnx sir

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  93. Hi Garry, by what name have you sent the email? I could not find any

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  94. Hello Sir. I want to know if it is possible to charge a 12V 7A battery using a 9 V 3w solar cell using your circuit.

    Thanks in advance.

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  95. sir could you please suggest any circuit for 1Hp single phase induction motor speed control, using PWM or variable frequency method.

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  96. Hi Shankar I think you can do it by using a standard fan regulator unit, by replacing its existing triac with a 40amp triac such as a BTA40A/600, you may refer to this article for more info:

    https://homemade-circuits.com/2012/03/how-to-make-25-amp-1500-watts-heater.html

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  97. hi sir,
    im having a 12v 1 Ah battery(3*4v) and series pannel 6v+6v+3v = 15 v>


    is it possible to charge the same with this circuit ??

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  98. Sir what's the meaning of the ground symbol between battery negative and R3.

    should we connect it to pv negative by a separate connection?

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  99. Hi emil, yes you can use the above LM338 circuit for charging for battery...

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  100. it's the battery negative....don't bother about it, just make the circuit as given in the diagram...

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  101. Sir Swagatam can this circuit charge a lithium ion battery? Im looking for a solar charger that can charge a lithium ion battery pack with overcharge protection .. thank you very much for your help sir..

    Paul

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  102. Paul, yes it can charge a li-ion batt but you'll need to monitor the current level in the given ammeter and switch off the charging process when the meter needle drops to zero....initially it will show the charging current of the battery and gradually begin dropping...

    for an automatic cut off you can opt for the second circuit from this article:

    https://homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html

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  103. Hello Sir,
    I have to charge 12v 2.2Ah Li-Ion battery using Solar pannel, will u suggest me what type of solar pannel should i use and what is the power, voltage, and current rating of pannel...

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  104. Sir, what will be the crt. of the charger

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  105. Hello Gaurav, you can use a 15V/1amp solar panel for your batt.

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  106. Sir, please send me circuit diagram of the solar pannel charger

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  107. its a circuit(ckt.) by mistake crt.

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  108. You can try the second circuit from the following link:

    https://homemade-circuits.com/2013/12/usb-automatic-li-ion-battery-charger.html

    replace the 1N4148 diodes with a single 6V zener diode, cathode will go to pin#2 and anode to the ground

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  109. sir, please also send schematic for 12v 2.2Ah lead acid battery charger using solar pannel and power rating of pannel.thankU

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  110. Pls sir can this circuit charger 12volt 100amh Inverter battery.?

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  111. yes the circuit can be used for charging the mentioned battery, but I am wondering how a 100 mAH battery could be used for operating an inverter

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  112. correction: it should be above 5K, preferably 10K for enabling a full range control

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  113. THANK YOU VERY MUCH FOR YOUR CIRCUITS AND EXPLANATIONS. I AM SURE YOU HAVE A WHATSAPP GROUP.MY EMAIL ID IS easokgeorge@gmail.com CAN YOU ADD ME TO YOUR WHATSAPP GROUP. IF YOU CAN GIVE ME YOUR EMAIL ID I SEND YOU MY PHONE#. THANK YOU ONCE AGAIN FOR YOUR GREAT SITE AND SHARING YOUR KNOWLEDGE EASO K GEORGE.
    .

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  114. hello sir , can i use this circuit for 6v solar panel and 4v battery....???

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  115. yes you can use it for charging a 4V battery from a 6V panel, but preferably the panel voltage should be 3V higher than the battery voltage

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  116. Hello sir.
    First of all let me say thank you for your fast replays.
    The FSD ammeter and R3 are not available at the market. Suggest somthg instead sir?
    Best regard

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  117. Abubakar,

    you can connect a suitably selected automobile bulb in place of the meter, initially this bulb will glow brightly, and when the battery is fully charged this bulb will shut down....but this will happen gradually...so you can consistently get the idea regarding the battery charge level through the bulb's intensity level.

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  118. hello Swag,
    i found this Solar, Wind, 2-Input Hybrid Battery Charger Circuit https://homemade-circuits.com/2015/09/solar-wind-2-input-hybrid-battery.html which is very simple not getting zener diodes in my area.

    moreover reading from the above the modern highly versatile chips like the LM 338 and LM 317 i can get all the parts for my personal project so i want to make a request from the above circuit.
    I have •Maximum Power: 265w •Maximum Voltage: 31.4v •Maximum Power Current: 8.44a
    •Open Circuit voltage: 38.6v •Short Circuit current: 9.03a solar panel with which i can modify and use
    but the other side is the shunt regulator from the wind mill if you could please add a circuit of Lm 338 and LM 317 with out zener diodes so i could use as a dual charger.

    thanks.

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  119. Hello Nito, a windmill should be ideally operated with a shunt regulator only, but if you are interested to have a LM338 circuit in its place you can easily do it by removing the entire opamp stage and replace it with a standard LM338 voltage regulator stage.

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  120. can i use any resistor in this circuit?please tell the values of r1,r2,r3,r4.

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  121. please specify the voltage output that you prefer to have, or the battery specification will also do.

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  122. Sir,
    I want to charge a small Li ion 3.7V 2100 mh battery using 10W solar panel with following spec.Voc 10.43V, ISc 0.90A, Vmp 8.95V, Imp 0.82A. Will it work?
    Parts used:
    LM337
    BC547
    R1 = 120 ohm
    R3 = 1 ohm
    D1 = ?
    D2 = ?
    P1 = 10K
    Can you please help and tell me if LM337 will work? What are the values for diodes? Thanks

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  123. Vishwa, yes it will work, just make sure to adjust the pot to get a precise 4V at the output and not 4.2V.

    D1, D2 = 1N5408

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  124. Sir,
    Thanks for your prompt reply. Wish you and everyone following you, a prosperous and healthy new year.
    Thanking you for your time,

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  125. You are welcome Vishwa, and Wish you too very Happy 2018

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  126. How much cost to make the circuit

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  127. Vishwa Mukh BharadwajJanuary 20, 2018 at 1:49 AM

    Sir,

    As I am new to electronics I have listed steps to be doubly sure of the connection:

    1. Positive of solar panel to positive of D1.

    2. Negative of D1 to pin 3(IN) of LM338.

    3. Pin 2(OUT) of LM338 to positive of D2.

    4. Negative of D2 to positive of battery.

    5. Pin2(OUT) of LM338 to top terminal of R1.

    6. Pin 1(ADJ) of LM338 to pin 1 of BC547.

    7 Pin 1(ADJ) of LM338 to bottom terminal of R1.

    8. Pin 1(ADJ) of LM338 to base of P1.

    9.Pin 1(ADJ) of LM338 to top terminal of P1.

    10.Pin 2 (base) of BC547 to bottom terminal of P1.

    11.Pin 2 (base) of BC547 to top terminal of R3. .

    12. Negative of solar panel to pin 3(emitter) of BC547.

    13 Pin 3(emitter) of BC547 to bottom terminal of R3.

    14. Pin 2(base) of BC547, bottom terminal of P1 and top terminal of R3 to negative terminal of battery.

    Thanks for your help.
    .

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  128. Vishwa, sorry I can't verify this because I am not sure which pins of BC547 you are referring by saying pin#1, 2 etc.

    It is better if you could refer to the datasheets of the respective devices and check the pinouts yourself and then connect them by comparing with the diagram

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  129. Sir,
    Thanks for your prompt reply. In my question I have mentioned the pin numbers as per the datasheet of BC547.
    Thanking you for your time please.

    ReplyDelete
  130. OK, then everything is fine.

    ReplyDelete
  131. Sir,

    Thanks a million for your prompt help. May I use the schematic in my youtube video. I will mention the source and link to your website.
    Thanking you for your time,

    ReplyDelete
  132. You are welcome Vishwa, you can use my circuit diagram in your youtube video with a backlink to my site, let me know when you have posted it.

    ReplyDelete
  133. Vishwa Mukh BharadwajJanuary 24, 2018 at 10:47 PM

    Sir,

    Please find below the link to my you tube video:

    https://youtu.be/Hmjy6bfFXkQ

    Please tell me what you think of it.
    Once again thanks for your prompt help.

    ReplyDelete
  134. That looks great Vishwa! Thanks for posting

    ReplyDelete
  135. Sir,

    Thanks for your valuable and kind appreciation.

    ReplyDelete
  136. I read somewhere that the float voltage for lead acid battery is around 13.8 volts, and that with this voltage, the battery could be charged as long as possible, without causing any damage to the battery. What is your take on that sir?

    ReplyDelete
  137. Sir I have to charge 24v 14ah battery by solar panel I have two 12v 20w solar panel can I charge the battery by them if I can what is the circuit

    ReplyDelete
  138. Sharath, put the panels in series and check if the output is around 29V at peak sunshine, if yes then you can charge the battery reasonably well with those panels.

    ReplyDelete
  139. Sir
    Can you just clarify. Using potentiometer P1, i set the output at 14V as measured by an ordinary multimeter. But when i connect a battery that voltage drops to 11.5 V. I am expecting the voltage reading to be maintained at 14V even when the battery is connected. Can you please help explain.
    Thanks very much.

    Pyke

    ReplyDelete
  140. Pyke, that is perfectly alright. As soon as you connect the battery the 14V must sink to the battery's discharge level, and slowly as the battery charges the level would be seen slowly climbing until finally the 14V is reached...and then you can assume the battery to be fully charged, and disconnect it from the supply

    To implement the above procedure we always make sure that the charging current is significantly lower than the battery's Ah rating....

    ReplyDelete
  141. Thank you very much sir. I appreciate very much you prompt and informative response. Keep up the good work. I salute you

    Pyke

    ReplyDelete
  142. you are most welcome Pyke!

    ReplyDelete
  143. Does this cut off the charging process when the battery is full? It is not Simple afterall.

    ReplyDelete
  144. Hello Sir. Can you provide a modified circuit of this so that it can be serve both a power source will the battery is charging and the battery as power source when the solar panel is not supplying power? Thank you.

    ReplyDelete
  145. If you keep the full charge voltage level from the IC slightly lower than the actual value, then the cut-off action won't be necessary and can be ignored

    ReplyDelete
  146. Andre, you can use the first design from the following article:

    https://www.homemade-circuits.com/solar-charger-circuit-using-transistors/

    ReplyDelete

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