# Help with ACS715 current sensor

Hello,
I am currently trying to get the ACS715 breakout board to work with an arduino micro. I followed the tutorial here and I am getting the wrong value. I have 2 circuits setup, one that should draw .12 A and one that should draw .6A. Both of them, following the tutorial, are reading around 14A. I have check both circuits with an amp-meter to make sure my calculations were right and they are very close.

Could someone help me?

Thank you,
Tyler

Hello, Tyler.

What are you using to supply power to VCC on the ACS715? Could you try reading the voltage between OUT and GND using a multimeter and let me know what that value is? Could you post pictures here that show how everything is connected?

-Nathan

5v for Vcc. The amps should be reading around .12A or 1200mA but I was getting 14.4A. Right now I think I have it working but I’m not sure if it is just for this case or it should work for all cases.

For calculating I have (((long)sensorValue-510)*5000/1024)*2000/133;

-510 because 510 seems to be the sensorValue for 0A, and * 2000 because well thats what gets me the right reading.

Actually I just looked at the IC on the breakout board and it is not the IC I though. Maybe they ordered me the wrong part? but it is a ACS714 x30 so the reason for the 2000 is because it should be 1000/66.

So I guess my only question now is is there a better way than just subtracting -510 to get the right value?

I can’t post pictures because this is part of a work project.

Thank you,
Tyler

Yeah, it sounds like you might have the ±30A version of the ACS714 Current Carrier Sensor. The sensitivity for that board is 66mV/A and the center point (for 0A current) is VCC/2 (2.5V for a 5V VCC). The value returned by the analogRead function at 5V should actually be 1023 not 1024, so 5000/1023 is a little more accurate and 0A will actually be 1023/2 = 511.5. Besides that, the general equation looks OK.

-Nathan