With h3 running attach a digital voltage meter to negative and positive battery connections and set meter to 20v. You should get 13.5 to 15.5v. if it is at 12.8v or 16v or less/greater than these two numbers you have an alternator or regulator problem. The terminals on both battery post should be replaced with quality connectors.
With H3 off same DVM attached set to same 20v range battery should be at 12.6 v.

 

Also, run a load test on your system...
Set up the same as above but turn on head lights, heater to full, stereo, rear defrost and other stuff.
Your value on DVM should be 13v or better if not you have a problem.

 

i'm putting a new negative cable on with terminal already connected rather than leave the new terminal on the old wire. I bought a negative wire at Salvos but noticed the smaller wire coming out of the new terminal, is not as thick as the old wire (its the one that bolts to the top of the wheel well next to battery). i was wondering if it mattered since its only about one size smaller. the bigger negative wire looks the same (i believe its 4 gauge). Smaller (new) wire looks to be a 10 gauge whereas the older one looks like an 8 gauge.

the terminal on the positive battery wire wasn't corroded, still looks good, unless the cable goes bad?

After hooking up new negative cable, i was going to put battery back in and see if it starts and give it the DC Voltmeter test.