I've read some articles like
shunt resistor, but I still don't know what to do.
Hmmm. I tried to polish up my crystal ball with a green plastic scouring pad impregnated with some sort of abrasive compound, but instead of a clear crystal ball (suitable for remote viewing and seeing the future more clearly), all I got was a cloudy crystal ball that reveals nothing! Now I have to polish my crystal ball again with a fine
red rouge, which I normally reserve for polishing homemade telescope mirrors. My bad.
So my suggestion is this: take a picture of whatever schematic you have that includes R6, R18, and R19 and upload it as an attachment to your next post. I offer this suggestion because I won't be polishing up my crystal ball anytime real soon now, and therefore can't see WTF those three resistors have to do with how, when, or where you install your "High-Side Shunt." Same-o, same-o with regard R8/R7, so please include those two resistors in your schematic image if you want us to tell you what they do.
If you just want to measure current somewhere, use an insulated wire of appropriate gauge for the current expected and install it where you would install your "High-Side Shunt." Leave enough slack in the wire to allow the use of a clamp-on type ammeter to measure the current. The clamp-on ammeter creates a magnetic path that intercepts the magnetic field created by current in the wire and (if you use the right type of meter) will measure AC as well as DC currents using a Hall-effect sensor.
