Hi, I'm trying to use the CS-4173-0R1 current sensor (datasheet here) to measure the current of a discharging battery, which I'm trying to discharge using a resistor.
I've built the following circuit with a load of 6 Ohms, which should produce a current of 0.83A, but the readings I'm receiving don't make much sense, for two reasons:
According to the datasheet, the current should be equal to Vout / 5. The arduino is registering values around 280, which means Vout should be 280/1024 * 5v = 1.36V. This, in turn means the current should be 280/1024 * 5 / 5 = 0.27A. That's 1/3rd of the current I'm supposed to be seeing.
When I measure the current using a DMM (black circle in the drawing) I get readings of 0.7A, instead of 0.83A.
Did I connect the sensor correctly? What am I doing wrong here?
The Nano's AREF (if powerd from USB) is only about 4.7V, measure it (the AREF pin) with your DMM and correct your code for that voltage instead of 5.00V. What voltage do you measure across the 6Ω resistor? From the module's pins 3 & 4?
EDIT: From the datasheet:
Full-Scale Sense Voltage VSENSE 150 mV
I = Vsens_out / 5 (unit: A)
Does that mean 0.150V / 5 = 0.03A, 30mA?
The Nano's AREF (if powerd from USB) is only about 4.7V, measure it (the AREF pin) with your DMM and correct your code for that voltage instead of 5.00V.
Mine actually outputs ~4.55V. This would mean the sensor senses a current of 0.24A, but it's still incorrect.
What voltage do you measure across the 6Ω resistor? From the module's pins 3 & 4?
When I try to measure the voltage across the resistor, I measure 0.7V and then it starts dropping slowly towards 0.5V, maybe even lower.
What did you intend regarding module pins 3 & 4?
EDIT: From the datasheet:Does that mean 0.150V / 5 = 0.03A, 30mA?
I honestly can't decipher this datasheet. The sensor has both Vsense and Vout outputs, so which one of these is Vsens_out...?
I took that to mean the maximum current is 30mA, you are trying to measure 83. ? ?
Good eye, that might be the case. I've sent an email to Inhaos (the manufacturer) to clarify this, I'll post an update if they answer. Thanks JCA34F!