One wire alternator conversion- best method to run the thick power wire

Can you explain that?
Its just hard to grasp how normal noise and ripple around 14 volts is reduced when a junction with the battery is introduced.
A battery resembles a huge low impedance capacitor. As Del suggests a length of wire adds resistance and inductance. Having an understanding of RLC circuits, transient analysis, AC circuits is a start. All the theory can be ignored, probing around with a scope can provide evidence. In circuit design for electromagnetic compatibility, switch mode power supplies, RF equipment, micro controllers..., circuit placement, and routing of traces/wires is extremely important.
The original wiring in classic cars predates micro controllers, entertainment systems and other equipment. Equipments typically have power filter capacitors, they will attempt to filter ripple. If battery is soft or pulled, the ripple current is detrimental to capacitor life and failure will occur. Similar ripple, if battery is more remote than equipment is to alternator output. There have been many posts on whine, headlight flicker, over charging .... most often related to inadequate wiring, and connection paths.