Use Local Voltage To Sense Remore Voltage (Meter)

"Is this April Fool's day?"

Only if your name is April

Here is perhaps a clarifying example

Voltage meter
A heavily loaded circuit is tapped as a power supply for the meter because the wires to tap into are "convenient"

The meter is read believing the value to be accurate, actually when enduring a .2 - .5 volt drop because of the load.

2nd device advantage
A meter needs TWELVE VOLTS to operate
This meter when connected across a circuit read AGAIN A-C-R-O-S-S a circuit can read voltage drop.

Wanna get fancy, use a gold flashed rotary switch and monitor voltage drop from three, four, eight places. Like ACROSS a PWM or MPPT controller (33 volts max)

Using telephone line wire can be fished where eighteen or twenty gage would have problems.

I would not use a loop powered voltmeter.

About sixty years ago on Armed Forces Day, I toured a Fleet Class US submarine at Mare Island with my dad. I got as far as the maneuvering room. A NCO showed me the analog instrumentation used for both battery banks. My father had to physically pry me away from the station. The entire crew including the XO were having belly laughs. One Chief hollered "There goes a destined, sure-fire electrician's mate!"

Yup, one of these critters is going on Quicksilver. Jesús, will help wire it into the panels, C60 Trace, alternator, and Distribution switch/breaker feed. The Cruising Eqpt Co panel meter is already connected to the L-16's.

I already have the gold contact rotary switch.

Oldfarts gotta have projects...

But with a major problem since it uses the negative power wire for the remove voltage. So it's not exactly reading the remote source voltage.

Also can't think of any RV or solar related voltage that I need resolution to 1 milli volt.

My recently installed meter with the 200 amp shunt
Has remote voltage sense option,
You can wire it to a local power source to power it, and it will sense voltage at the batteries not from the wires powering it

Is this April Fool's day?