Hello all,
I would like to use a 100A 50mv shunt to measure the current in a 30 amp circuit. Since the arduino can read less than 5v I figured I can it to read the measure up to 50mv. Then do the proper math to calculate the current running through the shunt.
My question is, is this a good idea to do? Is it safe, and accurate way to measure this small voltage?
All the best,
Adam
No; Probably not if you have to ask; and No.
Look for INA219 and INA169 at Adafruit and Sparkfun. See if those can be useful for you.
With high current, you have to design/wire your project carefully. A high ground current can decide to take a detour and go via or through the Arduino board.
Agree with Koepel, No that ain't a good idea.
However, the INA219 and INI169 only read to 3A and 5A respectively.
If you need upto 30A, then you really want a Hall Effect Current Sensor e.g.30A acs715 current sensor
Yours,
TonyWilk
The above, and 50 mV is really the bottom end of the scale. Even using the fixed built-in reference the analog reading will be about 50 at 50 mV input. You would need an amplifier circuit to bring the 50 mV to 1V, then you can get a decent resolution when measuring such small voltages.
TonyWilk:
However, the INA219 and INI169 only read to 3A and 5A respectively.
That's because of the 0.1ohm shunt resistor on the breakout boards.
If you connect a 100A shunt in parallel to that 0.1ohm shunt, then those boards can measure higher currents.
There are restrictions though. The INA219 is designed for ~12volt high-side measurements.
Need to know the galvanic relationship between the Arduino and the shunt.
Leo..
Thank you all for the help. I will certainly give the current sensor a shot. All makes sense now why my original idea would not work.
What is the voltage of that 30 Amp circuit? AC or DC?