Wire size for battery bank
If you've got 4-6v Trojan t105 batteries wired for 12v with 2/0 wire between them would 2/0 be the proper size to run back to your converter/charger which is 12' away? And I guess the hot wire would n...
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You could get by with 8ga but 4ga is still not terribly difficult to run and you will have less current loss. Where people go off the rails is in looking at charts for cable sizing based on less than 3% current loss as though this is of critical importance.
If your charger charges your batteries on shore power in 3 hours with 3% current loss (97% of current is getting through) then going to smaller gauge wiring with 10% current loss (90% of available current is getting through) is only going to take an extra 12 minutes of charging time.
The wire from the tow vehicle's alternator to a trailer or from the truck alternator to a camper is going to be 8ga in most situations and it is going a much greater distance to the batteries but it works well enough.
FYI it is not the diameter of the wire but the area of the cross section of the wire that determines how much current it can pass and how much loss there will be. Take a 20' run (40' in total) and using 2ga wire the voltage drop is 0.53% and going with 4ga the drop is 0.85% and going to 8ga the drop is still only 2.15%.
If your charger charges your batteries on shore power in 3 hours with 3% current loss (97% of current is getting through) then going to smaller gauge wiring with 10% current loss (90% of available current is getting through) is only going to take an extra 12 minutes of charging time.
The wire from the tow vehicle's alternator to a trailer or from the truck alternator to a camper is going to be 8ga in most situations and it is going a much greater distance to the batteries but it works well enough.
FYI it is not the diameter of the wire but the area of the cross section of the wire that determines how much current it can pass and how much loss there will be. Take a 20' run (40' in total) and using 2ga wire the voltage drop is 0.53% and going with 4ga the drop is 0.85% and going to 8ga the drop is still only 2.15%.
