I am installing new VE smart lithium’s 12.8 200 amps X 2. I have run a single 4/0 from my multiplus 12/3000 120v to a positive bus that is fused correctly. I cant fit 2x70 mm in the cable path, I am using 4/0 to a battery switch from the lithium’s and then on to the positive bus bar. . Do I need to use 4/0 from my BMS to the positive bus bar? I am only using 2 awg for my starter/alternator battery hookup And would use the same size cable from the start battery side of the BMS to the start battery.