In the real world, almost no one gets their performance out of really large cable because few people know how to make proper connections. Connections is where all the power is lost, not the wire itself.
When I am building cable for winches and batteries stuff (like 50kW LASER power supplies), what I do is buy those big-ass honkin' terminals that have a cup to stick the wire into. The cup should be as close to the same diameter of the cable as is practical for the sizes they have. Then I stick the wire in and fill it up with molten solder.
It takes a lot of practice to do this right without buggering up the end of the insulation of the cable and also not get a cold solder joint, but that's the only way to get your money's worth out of thick gauge wire. The trick is to preheat the terminal with a torch, and then fill all that space with solder as quick as you can. Then the very moment you have the cup filled and all the spaces between the strands filled, remove the heat and get a heatsink clamped onto the cup so the wire insulation doesn't burn too bad. I normally have some heatshrink on there too; when things cool down enough slip the heatshrink over the end and then shrink it down to keep the strands sealed from the outside world.