xl4015(Adjusting the current)

[isaacsong23]

Hello guys!!Thanks for taking the time to read this forum!!I am interested in looking up circuits like this and coming up with stuffs like battery charger, using this circuit i know how to adjust the voltage use the voltage potentiometer but for the current i am not too sure how do i adjust it?EG my input voltage is 12V and 4A, i want my output to be 5V and 3A, so my output current limit is 3A , I know that to measure the current i need to connect the ammeter in series to a load, but can i use one fixed load resistance connected to my ammeter, for eg, a 5V Computer fan, and adjust the current to 3A and than when it is set, i swap the 5V computer fan with my diy TP4056 battery chargers (3 of it, i will set the output voltage is 4.2v) will the current output remain 3A evrn though the load has changed? Thank you!!

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[ABHIRAMSHIBU]

What I normally do is set voltage first(CV). Then switch multimeter to ampere mode. Then connect a fully discharged battery , set current(CC).

Use multimeter in parrellel to measure voltage and in series to measure current..

[isaacsong23]

Ohhh, but how do i preset the intial current going into the load?like set the limit, i wouldnt want 3A going straight into the tp4056 charging module, is there anyway to limit the current before i connect it to the battery load?Limiting it to 1A. Thank you for the advice!!:)

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[sleemanj]

To set the current limit, first set the voltage limit, you already know how to do that.

Then put your multimeter in the 10A current range and probes in the appropriate sockets for measuring 10A current.

Short the output of the converter through the multimeter, so you can measure the "short-circuit current".

(Obviously, you ONLY have the multimeter connected here, don't go shorting out a battery connected to the output!)

Adjust the current potentiometer until it is at the limit you desire.

[sleemanj]

i wouldnt want 3A going straight into the tp4056 charging module

As an aside.

That would not happen anyway, for starters the TP4056's purpose is already to limit the charge current, that's like 90% of it's job, intelligently limiting charge current.

The TP4056 will draw precisely as much current as it wants/needs to draw, the fact your power supply COULD give it eleventybillionamps is not important, if the TP4056 wants 1 Amp, it will take 1 Amp.

When talking about a normal constant voltage power supply you can think of the current rating as what it CAN supply to maintain it's output voltage, it will always supply as little current as necessary to do that.

[Seekonk]

If you are serious about protecting things, put at least 0.5 ohms in series with the power to each TP4056.  Sure they say they are self protected, but they are a linear regulator.  The voltage difference between input and the battery times the amps is what this device has to dissipate.  In ideal situations (those that the mfg always uses) there is enough board copper to dissipate the heat.  Check the spec sheet, that resistor is there.  With it half the heat is dissipated in the resistor instead of the chip. I use a 1 ohm without problems.

[isaacsong23]

Thank you so many, guys!!!Really appreciate the forum here !!super friendly and helpful, last question to make sure, haha To short the buck converter I simply connect my ammeter(10A  & COM fused), 10A to the positive output terminal and COM to the Negative output terminal correct? and adjust the current potentiometer from there Thank you!!!

[sleemanj]

Thank you so many, guys!!!Really appreciate the forum here !!super friendly and helpful, last question to make sure, haha To short the buck converter I simply connect my ammeter(10A  & COM fused), 10A to the positive output terminal and COM to the Negative output terminal correct? and adjust the current potentiometer from there Thank you!!!

Yes that's correct.

[isaacsong23]

Thank you so much guys!!Last question!Do i have to set a limit for the  voltage( EG 6v or it will get too hot)  and current(5A current is the max the buck converter can draw) on my PSU before shorting the buck converter? Or should i just  leave it as it is and supply 6V dc to the buck converter and than short it to adjust the current , does limiting it really matter or should i just ignore limiting the voltage and current?Thank you!!:)

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[sleemanj]

Doesn't matter.  The XL4015 module won't be able to supply more than 5 amps short circuit current anyway, which is within your meter's capabilities.

[isaacsong23]

I see!!Thank you!!:)

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[isaacsong23]

Okay So i tried the circuit but multimeter(Current in DC) does not show the current reading(it shows 0Amps on my multimeter) of the XL4015 ic chip when i connected it in parallel to multimete and short it, my input voltage is 10V and i did not set my current limit on my PSU,my output voltage is 5V, any advice!!?Thank you!

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[sleemanj]

Okay So i tried the circuit but multimeter(Current in DC) does not show the current reading(it shows 0Amps on my multimeter

Most likely you have previously blown the 10A fuse on your multimeter.

And to be clear, you are shorting the OUTPUT of the XL4015 board through your meter, not the input.

[timara]

I gave 5v 2amps input.. And adjusted the output voltage to 3.7v for driving led... But i short the output of ic by adjusting ammeter.. It shows 3amps...by rotating the cc resistor curent is not changing... Plz help how to adjust current?...

[sleemanj]

There are approximately 20 turns end to end of the potentiometer, most likely you are just not turning it enough turns.

I often get customers who buy similar products and don't realise the potentiometer can turn so much, they do like half a turn one way, and half a turn the other and wonder why nothing happens.