DIY Constant Current Load

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Introduction: DIY Constant Current Load

About: Awesome Electronics Tutorials, Projects and How To´s

In this small project I will show you how to make a simple adjustable constant current load. Such a gadget is useful if you want to measure the capacity of chinese Li-Ion batteries. Or you can test how stable your power supply is with a certain load. Let's get started !

Step 1: Watch the Video!

The video gives you all the information you need to build a constant current load. But I will present you some extra help in the following steps

Step 2: Order Your Parts!

Step 3: Build the Circuit!

Here you can find the schematic for the build and the board design that I created. Make sure to interrupt the copper traces underneath the LM358.

Step 4: Success!

Now you should be able to build your own constant current load.
Feel free to check out my Youtube channel for more awesome projects:

http://www.youtube.com/user/greatscottlab

You can also follow me on Facebook, Twitter and Google+ for news about upcoming projects and behind the scenes information:

https://twitter.com/GreatScottLab

https://www.facebook.com/greatscottlab

27 People Made This Project!

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132 Comments

0
AnvitV
AnvitV

4 years ago

Hi,

I have tried to recreate this exact circuit, but have always failed. What do we attach at "load", like a resistor or what?

0
SašoD1
SašoD1

Reply 3 years ago

The "load" is the battery that you want to discharge.

0
Samnonyellow
Samnonyellow

Reply 4 months ago

So the 5V on the op amp and pot can be a 9v battery?
I've seen a schematic where someone uses a 7805.

P.s
I know I'm incredibly late !

0
SašoD1
SašoD1

Reply 4 months ago

Had to reset my password so I could even reply to you 😅. Yes the LM358 can take up to 32V supply voltage. With higher voltages the current setting will be a bit more "jumpy" because the voltage on the potentiometer will change faster. You can add a resistor that has roughly the same value as the potentiometer between it and the + rail, this will bring the pot voltage down.

0
Samnonyellow
Samnonyellow

Reply 4 months ago

Wow thanks alot man I appreciate it. I will apply those chsnges

0
MirekF
MirekF

6 years ago

Hello ,

What programs are doing in electrical circuits for universal board

0
3runo
3runo

Reply 1 year ago

Lochmaster

0
ThomasVDD
ThomasVDD

6 years ago

Great project! What is the difference between an IRLZ44N and an IRFZ44N? I don't know why it works with the IRL, but not with the IRF.

0
3runo
3runo

Reply 1 year ago

IRLZ44 is a logic level mosfet instead IRFZ44 is regular one. IRFZ44
needs a higher Vgate to turn on (Vg~10V). At 5V and 3,3V (Logic levels)
the IRLZ is the rigth one. If you use 12V OTOH the IRFZ44N will work

0
3runo
3runo

1 year ago

Can I power the circuit using 24V instead of 12V?

0
vrooom
vrooom

Question 1 year ago

Hi GreatScott, I have used this schematic, slightly changed and made PCB to test the 18650's. But i have a doubt, when you discharge the cell with 1ohm load and 5ohm load separately with same discharge current. Then for both the scenarios is the battery capacity calculation same or do we also have to take into load resistance value into consideration?
i have asked the same question here with circuit and PCB. https://electronics.stackexchange.com/questions/53...
Thank you

WhatsApp Image 2020-11-17 at 01.12.50.jpegWhatsApp Image 2020-11-17 at 01.12.51 (1).jpeg
0
satannatas
satannatas

Question 1 year ago on Introduction

Could I use an IRFP250 MOSFET ?
It has a G-S threshold of min-2v max-4v
Thanks

0
ahmedfebri13
ahmedfebri13

1 year ago

how to combine the module ammeter and voltmeter to this schematic bro? please.....

0
SamikshaB1
SamikshaB1

Question 3 years ago

Can the Opamp supply sufficient current to turn on mosfet?
Can we use another MOSFET like IRF640N or so and another OPAMP IC like LM341

0
JohnW669
JohnW669

Answer 2 years ago

A mosfet is a voltage driven device with a slightly capacitive load. The opamp should have no issues at all driving it. Make sure you use the IRL version

0
_JoH_
_JoH_

4 years ago

I've been reading the comments and some people are asking about the different between the IRLZ44N and the IRFZ44N.

I was only able to find the IRFZ44N at my local electronics store, some said it works, others said it doesn't.

But there was no definitive answer about the difference of those 2.

Can anyone please help?

0
albertoaav
albertoaav

Reply 2 years ago

IRLZ44 is a logic level mosfet instead IRFZ44 is regular one. IRFZ44 needs a higher Vgate to turn on (Vg~10V). At 5V and 3,3V (Logic levels) the IRLZ is the rigth one

0
HarunB9
HarunB9

Reply 3 years ago

İ made it using IRFZ44N powered it with 12v and it worked perfect. I can adjust the constent current with pot.

0
GreatScottLab
GreatScottLab

Reply 4 years ago

IRFZ needs a higher gate voltage to turn on. If you want to power the circuit with 12V it does not make a big difference. But If you want to use 5V and below I would recommend the IRLZ because it requires a lower gate voltage.

0
FlingingB
FlingingB

2 years ago

Hi, can this be used to test a 1.5v AAA battery?