Battery to body ground

[H2OnSnow]

While this is largely true, most people don't have the abilty nor desire to put the time into calculating all the various loads to determine the perfectly sized wire gauge for the shared ground path. The oem can do that. They are incentivised to do so for weight and cost savings. But for all us schmucks it's way easier to just buy a 6 gauge starter cable for $10 and slap it in for the ground cable. You can't over ground your electrical system, so doing this hurts nothing and ensures you don't accidentally undersize your ground path. Plus now you have flexibility if down the road you decide to add to your electrical load via new lights or new stereo.

The metaphor for different sized arms doesn't really work. It's more of a different diameter hose situation. You're limited by the smallest hose diameter in a chain of hoses. Which is still a flawed metaphor, but it's closer to reality than the arm comparison.

Just replacing a braided ground strap with a large gauge cable may or may not give you a "better" ground. The braided strap from the frame to body, engine to firewall, etc. is a braided strap for a reason. It is VERY flexible to withstand all of the flexing due to rubber mounted engine and body; and it has many very small strands, which for many purposes is better than fewer large strands. If you buy very "over priced" small strand cable, then your argument is valid; if you buy the Amazon priced cable that is 1/20th the price of the good stuff, then you probably have an inferior ground system. The 2ga cables that support the starter are the only ones that can properly be the few large strand cables, as they are for running the starter and little else.

 

[Radiohead]

Since the OEM relied on ground connections that really only needed to make it past warranty and not much farther, it's not unreasonable to introduce fresh ground paths in the same general areas to preserve electrical function.

Having said such a bold statement, unless new, higher amperage components are introduced into the circuit, there's not much reason to increase conductor size.

As far as RF goes, it's a different idea concerning panel bonding. Similar, but not exact, still a return path for currents but made for different reasons.

 

[EvilGenius]

The 2ga cables that support the starter are the only ones that can properly be the few large strand cables, as they are for running the starter and little else.

The positive cable runs direct to the starter yes, but on these trucks the entire electrical system runs off that wire. It runs from the battery to the starter post and from the starter post to the junction block and then to the big firewall connector.

So while there is some merit to the multistrand argument for flex resistance, GM didn't seem to care about it for the positive wiring for whatever reason.

 

[Radiohead]

I can't imagine, in a properly maintained engine bay environment, the cable flex to the starter being an issue. Now, if it was a solid conductor (a single strand like Romex) that would be a problem, over time. But that's not realistic, as using fine threaded welding cable is complete overkill.