Yep,yep,nope and yep, LOL,whatever.
Just some basics. The bigger cable is generally needed for the load, not to charge the battery. That is why it is run to inverters, and on long runs, you can see some fine installations on the net, in "audio race cars". BUT, the drawback of a lot of vehicles, can be the wire from the alternator to the battery, a lot of GM's especially, go to a junction block on firewall, down to starter, then batt. is charged by the big cable from starter to batt. Generally undersized for bigger than stock alternators, BUT not always, depending on your driving conditions, and electricity usage. A lot of times, just the same size cable run straight to battery is fine. A alternator is for the load, charging is secondary. They are not meant to charge a dead battery, besides, high amps into a dead/very low battery is bad, and dangerous, as now you are creating a bomb. Generally battery charge should never go over 20-30 amps. remember all those burnt up hoods on 80-90's chevys,? And a melted lump of alternator under the hood? Or seized alternators? This is from jump starting a dead battery, and driving it to charge! Unfortunately,I have seen lots of "mechanics:" do this,also. Good upfitters always split things off, with the wiring.
Also, over the years, I never get "technical" replacing even customers cables, as many refuse to purchace the factory items, because they come as a harness assembly, can be quite expensive, just run it along outside, wire tyes, snip ends off of old cable.
I could go on, but that is just some basic stuff. The average person will never need a super hi output alternator, or the occasions are so rare, not worth it.
