DC Current Data logger / DC Current sensor (DC Current recorder)

[electrochemical]

Dear experts,

I am in need of DC current data logger for a variable DC voltage.

Voltage vary from –5 V to + 5 V with a max DC current of 800 mA.

Voltage is varied with time say 0.2 V/s and apparently current is also varying with reference to resistance, which is also slightly varying. Since the potential is applied in chemical / salt solutions and on applied potential, by means of electrolysis of the solution the concentration of salt changes and hence resistance of the solution is also changing.

So, I used, ACS712 Hall Effect Sensor (5 A), because in most of the forums, this one is referred.

Then I cross checked the recorded data with ammeter (in series) manually.

But the measured current did not match with the ACS712 reading. Errors are more than 43 %.

In some case it is still higher.

I think its unreliable under varying resistance. (But I am not sure about this.)

Some experts suggesting for Adafruit INA219, but still didn’t try that one.

In this scenario, I request suggestions for a suitable DC current sensor under varying resistance measurements.

Thanks in advance

[hammy]

You need to post more information ! Wiring diagram and sketch please .

Varying resistance has nothing to do with your issue - look at ohms law .

INA219 is nice as it has a digital output and not so dependant on the Arduino

[gilshultz]

Can you post a Schematic, or a hand drawing of how this is connected and technical links to the hardware items.

[Wawa]

Note that an INA219 can't be used with, and can't measure, negative voltages.
It can however measure bipolar currents.
Leo..

[TomGeorge]

Hi,
Can you please post your code in code tags?

Can you please post a circuit diagram of your project, including power supplies?
Use a pen(cil) and paper and show an image of it would be fine.
Please do not use a Fritzy picture

[johnerrington]

@electrochemical

The measurement is galvanostatic

Galvanostatic refers to an experimental technique whereby an electrode is maintained at a constant current in an electrolyte.
Galvanostatic

If you are driving the electrode at a constant current why do you need to measure it?

@electrochemical

Then I cross checked the recorded data with ammeter (in series) manually.

But the measured current did not match with the ACS712 reading. Errors are more than 43 %.

ACS712 Current Sensor: Features, How it works, Arduino Guide - Latest Open...

There is no way two ammeters in series can experience different currents. So EITHER your code is converting the reading incorrectly, or one of the ammeters is faulty. Or you have them connected wrong.

[Wawa]

@electrochemical

I tried to measure with ACS 712 but its recording ar incorrect.

And the code was ?...

@electrochemical

trying to substituting them with INA219 type sensors

And your proposed circuit is ?..

Remember my hint about the INA's common-mode range, 0-26volt, which is not negative.
Leo..

[johnerrington]

@electrochemical

But in realt time, if at 1A the electrolysis carried out there will be a change in current too, because of the change in the concentration of the electrolytic solution due to primary and secondary chemical reactions.
Say in 5 min. it is dropped to 0.90 A (actual data) and the current should be maintained manually.

If you want to perform galvanostatic electrolysis you use a constant current psu. Like this

skillbank: PC maintenance and IT support

It seems to me you are manually trying to maintain a constant current by monitoring the current and adjusting the supply voltage. So the process is neither constant current nor constant voltage.

You need a circuit that measures and adjusts the current automatically.

[electrochemical]

Tried Adafruit INA219 and cannot be fetched the polarity. Despite that sensitivity is poor as said by Leo and its just again comparable with ACS712.
So shifted to DataQ Current datalogger.
Thank you experts for your valuble suggestions and time.