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How to Make a 25 Amp Battery Charger Circuit Using LM338 ICs

Last Updated on June 14, 2025 by Admin 14 Comments

This circuit is capable of doing delivering as high as 25 Amps of current at any chosen voltage between 1.25 V to 30V according to the adjusting of the presented pot. The current is continuous in spite of the voltage settings. The circuit can be utilized for charging batteries in range of 50 to 200 AH.

The figure below demonstrates an easy design of a 25 amp solar battery charger power supply circuit which might produce a continuing 25 amps of current from any source which can be capable of produce currents exceeding beyond 25 amps and at 32 volts maximum.

We realize that the IC LM338 is stipulated with a maximum of 5 amp current, the IC controls anything above this limit.
By hooking up 5 of these ICs in identical it hence turns into possible to develop a current output of about 25 amps. The great advantage of utilizing these types of ICs is that, these kinds of products are internally safeguarded from thermal runaway circumstances and short circuit or overload problems.

It implies the current circuit instantly evolves into protected from these kinds of unfavorable guidelines therefore turns into totally unbreakable provided the input is not surpassed above 32 volts.

In spite of this the ICs simply cannot be instantly associated in parallel, simply because that could result in a difference in the voltages at the output from each of the ICs which often motivates an fluctuations between the IC dissipation, this would not be beneficial to the all round operating of the circuit.

For that reason the additional parts by means of the opamp and the transistor happen to be incorporated into the circuit which manages and also handles a persisting voltage output from all the ICs maintaining the circumstance nicely well in hand.

 

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Tagged With: Amp, Battery, Charger, ICs, LM338

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Hey friends, Thanks a bunch for stopping by this site! I am an engineer with a Bachelor of Engineering in Electronics and Telecommunication. One of my passions is gathering information from all sorts of electronics books and tutorials. I then take that information and compile it into a language that is super easy to understand. My goal is to make those complex electronics circuit concepts and technical terms much more accessible for all the new and budding electronics engineers out there. I can also design customized circuit diagrams as required by the users.
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ebin
2 years ago

is the 1.5k resistor at the bottom right a potentiometer?

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Author
Admin
2 years ago
Reply to  ebin

It should be a preset actually, not a potentiometer

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Janith0000 Laknal
5 years ago

Im going to make a wirless charger…
Can i use this cct after the converter to charge a car battery….
24V 10A charger

And what should be the input vdc voltage for the system?

0
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Author
Admin
5 years ago
Reply to  Janith0000 Laknal

you can use it, or you can be simply use a LM196 IC based circuit…input should be 3 V higher than the expected output.

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Nathan
7 years ago

Hi, Can I use LM358 instead of LM308? its hard to find. Or, can you suggest substitute for LM308? thank you.

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Author
Admin
7 years ago
Reply to  Nathan

pin#8 is not relevant…therefore you can use any opamp according to me… a 741 or LM358 or LN321 all should work.

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Ericson
7 years ago

If I want to limit the current to charge small batteries what will be the modification.

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Author
Admin
7 years ago
Reply to  Ericson

you can remove the number of LM338 ICs appropriately, or you can increase the values of the 0.1 ohm resistors as per the need

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j
8 years ago

Thank you. also is the 2n2907a ok to use as the 05 is hard to find.
I’m using this circuit as a high amp 24v to 12v dc convertor

0
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Author
Admin
8 years ago
Reply to  j

yes it’s OK to use 2N2907 instead of the shown PNP…

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Praise
5 years ago
Reply to  Admin

Hi, Can I use this circuit to charge a 18650 Li-ion battery of capacity 22000mAh,4.2V(connected 10 in parallel)

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Author
Admin
5 years ago
Reply to  Praise

yes definitely you can use it, just be careful with the input current

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J
8 years ago

Can I get more info on 338 circuit please component list thanks

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Author
Admin
8 years ago
Reply to  J

All 0.1 resistors are 5 watt rated, while other resistors are all 1/4 watt…please specify if you have anymore questions

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