Hope someone can help with this question...
What size cable do we need to run from our pick-up truck to the inside rear of our travel trailer where our Battleborn battery bank is? We are estimating a total run length of 70-75 feet one cable or 140-150 two cable lengths. It will be going to two (2) Orion TR Smart 12/12-30 Isolated Chargers.
Not sure if that would be practical he Voltage drop over that length will be crazy.
Use the Max size you can fit into the Orion if possible. 6AWG is the max size or 16mm2.
Maybe you will have to bus bar it and run fatter stuff along the trailer to try minimize the voltage drop.
Try the Victron Toolkit app or some other cable app to run some cable length/amp scenarios.
If you are running the two Orions in parallel then expect a max current of 60 amps, assuming your alternator can put out that much power. A 10% voltage drop for that distance and power would require 1 AWG wire each way. You'd may need to splice in a smaller wire at each end and probably at whatever connection you are making between the tow vehicle and the RV. The standard 7-pin connector might not support 60 amps so something else that accepts wire that size and current might be better.
The minimum wire size to support 60 amps is 6 AWG using 90 degree C sire (like THHN) or 10 AWG using 105 degrees C wire (marine wire). But at your length and current you'd loose 75% of your voltage with #10. and 40% with #6. So use smaller wire for very short distances only.
I used this calculator (there are others on-line as well):
