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

OK NOW you've got it charging, NOW you have a different problem, most likely "harness voltage drop"

There are several possible causes for over voltage

MOST LIKELY

1....Voltage drop in the wiring harness

2....Poor grounding between VR and battery negative post

3...In a few cases a battery going bad

4...In a few cases, a VR out of calibration

Start by assuming it's either 1 or 2. You need to make some tests

A........With key in 'run' but with engine off, access the "switched ignition" or "ignition run" (IGN 1) coming out of the bulkhead and feeding the ballast resistor

Depending on the year of the car, the ign run feeds

the ignition system

the voltage regulator

On 70 / later, also feeds the alternator field (blue)

and some smog doo dads if used, and electric choke

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

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.

If you have harness drop the top suspects are bad bulkhead connections, bad connections at the ignition switch connector, or the switch itself. More rare is problems at the ammeter, and last, most rare, is a failure of the factory welded splice

Now it's time to go read the MAD article............

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

and

http://www.madelectrical.com/electricaltech/howitworks.shtml