This is calculator for Voltage drop in wires for different wire sizes
On this page: https://visbis.com/newsinfo/electrical-engineering-information/wiring-installation-and-all-about-wires.html
we have discussed some material properties of wires and talked about losses associated with resistivity of metals.
Here we provided calculator for Wire Sizes, Wire resistance, Voltage drop on the specified length as well as Voltage at the end of wire if you would take in account wire resistivity.
Many people didn't realize, that wire resistivity can be used advantageously for current limiting purposes. Typical example: your alternator is 100A maximum output and 60A is used all the time for vehicle functions. Only about 20A can be given to the trailer battery to charge utility battery. Thus we will choose 2mm diameter wire and at 5m wire length we will limit current guaranteed never reach 100A as voltage drop at 100A will be about 6V in copper wire. At 6.5V on the end, the secondary battery won't consume it for charging purposes.
Please rout all your questions and comments to forum.