Electronics > Beginners
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:
--- Quote from: isaacsong23 on March 31, 2017, 04:00:03 am --- i wouldnt want 3A going straight into the tp4056 charging module
--- End quote ---
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.
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