LouC wrote:
The way I looked at it, was the surface area for the current flow (amps). Now if that little terminal for the wingnuts was enough surface area for the current flow to power a starter motor, don't you think the auto companies would save money by getting rid of conventional cables that cost them money? Of course they would if it was adequate, but they didn't so that tells us something. I feel the wing nut terminals are provided to add things that people may not want to wire in through the boat's electrical system, they are not really intended to carry starter loads of 500 amps and more. The surface area of a full size battery post and clamp is far greater. Since I stopped using wing nuts when I put in my dual battery system about 7 years ago, I have not had any trouble with batteries or starters.
You are right on as far as your train of thought! (Like you NEED me to tell you this!!) Lets stand back and look at the whole system.
Marine batteries have 2 types of post. The bigger wrap around ones (for starting) and the wing nut post for "add ons". I am not sure that the wing nut post on the battery, is made to handle starting currents. NOW my battery switch uses the 5/16th or 3/8s post/lug type connector. In some cases the "nuts" are bigger for that thread size for a better/larger surface contact. But, at the block and starter, they are also using the post or lug type connector too.
Engineers need to get out in the real world some times. OR Does it really matter the type used. The starting is only used for a few seconds at a time.