Age old question...Bad Battery or Bad Alternator???

"SO get to the highest reading on the ballast resistor. Hook one probe of your meter to that post, and hook the other probe to battery POSitive.

You are hoping for a very very low reading, the lower the better. If the reading is more than .3V (three tenths of one volt) that is at least part of and probably most of the problem

I was unsure which post to measure but I obtained the below readings:
1. engine cold - no start since last night - engine off
top post (blue wire) measured 7.04v - bottom post 1.67v
2. engine warm after 30 minute cruise - engine off - 12.83 top & bottom
3. engine warm & off - 0v measuring bolt and white ballast area.

B.....VR ground. This time, run the engine at a fast clip to simulate "medium cruise" RPM. Make this test first with all accessories off, and again with lights, heater turned on

One probe to battery NEG post. The other stab into the VR mounting flange. Stab through any paint or rust. Again, a low reading is what you want, and zero is perfect.

This VR Ground test produced readings of .13v and .55v with accessories on.