I am doing a 3x 100amp hr lithium battleborn setup in my fifth wheel (12v) with the multiplus II. As I do my research it seems everyone is using 4/0 for the battery connections and to the multiplus. However, as I look in the multiplus manual it says that 1/0 AWG is sufficient for the cable lengths(2 to 3 feet). Not sure if everyone is being overly cautious or if there is another reason. From my standpoint there are very limited suppliers that can get me the cable and terminals in a timely fashion for my trip if I have to go 4/0 but auto shops and the big box hardware stores all carry 1/0 or smaller and its a bit less expensive which is always nice.