We've been preaching this for years!
Here is the scoop,
You are driving several jeeps in very close formation, but none of them actually connected...
Loose fasteners, rust, mud, paint, ect. all conspire to keep your jeep from grounding correctly.
The reason your jeep didn't come with dedicated ground wires was...
It would probably cost $3 extra dollars at the factory to add proper grounding, but the factory thought that was too much.
And once your jeep made it through the 12 month warranty period, grounding problems were money in the bank!
Either you paid to have them fixed, or you paid to buy a new vehicle...
On your alternator problem,
Use at least a 10 gauge wire, run it from the alternator housing to the primary ground...
In your case, that will probably be your negative battery terminal connector.
As you have found out, PROPER grounds are few and far between.
Here are some things you might do to insure a proper ground and power system...
Now, from your binding post, you can run as many grounds as you need too...
Like one to the dash, one to the tail lights and fuel tank, one to the ignition module and engine block...
If you live in a wet area, DO NOT use woven ground straps.
They are open to everything the environment can throw at them and don't fare very well.
For battery cables, use at least a 4 gauge fine strand wire, or 2 gauge 'battery cable'...
An excellent wire to use for battery cable is welding cable.
Welding cable is fine strand, carries more current and is easier to bend and shape.
Welding cable is usually virgin copper, no alloys, so it will carry more current for the size of wire and will solder or crimp better.
Welding cable is easy to acquire, even NAPA sells it.
Welding cable has a rubberized insulation that is resistant to abrasion, chemicals, heat... All the things you find under a hood.
Welding cables will fit into any of the common battery terminals...
I recommend the sold copper, lead cadmium plated, crimp on style battery terminal connectors NAPA (and others) sell.
They are the correct size and shape, are much sturdier than lead terminals, and have the correct type of stainless steel battery bolt.
When you terminate your wires, use a solid copper terminal.
Some will be lead or nickle plated, and that's OK, but the base metal should be copper, not steel or lead!
Crimp on these terminals, then solder them down.
Crimping is only a MECHANICAL connection, solder is an electrical connection...
Don't forget to use glue fill heat shrink tubing!
This seals out the elements to make your new cables and wires darn near impervious to the elements!
Different colors of heat shrink will show color-coding for positive and negative, as well as some different colors for wires, like the feed to the alternator after the fusible link...
(Helps keep the harness straight in my head)