[padredw]

Shunt needs to be at the battery in order to measure the total battery current.

Yes, I will add from personal experience: The Renogy battery monitor came with inadequate length of wire from shunt to display. I had to purchase wiring from a different source to bring the monitor inside my trailer.

The point? The wiring to the display can be extended; the shunt needs to be kept close to the battery. Also, the wiring for the shunt requires heavy, thick wiring; the wiring to the monitor display is small wire--though I can testify that in my case it was made up of 5 very small wires which required delicate splicing.