My car appears to not charge the battery properly. I think this problem has been around for quite some time, and I've replaced the battery several times, but I have a new one in right now. When measuring voltage while the car is running, it is sometimes about 12.5v and sometimes around 13.4v with no changes, meaning, I can be measuring the voltage at the battery, and it will change suddenly.

I took my car to a shop to have the alternator replaced, as it seemed to be the problem. They replaced it, tested it, and the same thing was still happening, so they put my old one back in. What I'm reading is that it could be ground straps, but I want to make sure there wouldn't be something else causing this specific behavior. I get the same readings (12.5 or 13.4) even when measuring at the negative cable while it is detached from the battery (car running without the battery connected), as this is the suggested way to test according to the repair manual.

Any thoughts on other things to check?

 

Did you check the power stud on the FALSE BULKHEAD??

A loose connection will do all sorts of strange things.

Also check all the large cables from the alt all the way back to the MEGA-FUSE and battery.

 

This isn't necessarily direct fix scenario to say, ..its a hunt and search.
Like Bob said, check the cables and bulkhead....if there's any corrosion in them, you won't get it out, so replace them as needed. Your statement on grounding lanyards (especially the one coming off the battery negative) is a good idea also. Clean your grounds also.

 

I hadn't, and you hit it right on the nose. There is corrosion on that connection. On one side it's a solid 14.45v and on the other side it's 12.5 to 13.4. Now I just have to figure out the easiest way to fix it. Thanks so much!

Bill

 

It's a copper or brass stud so take it out and wire brush or 'bead-blast' it!!!!!
If it is 'burnt' then replace it!!

bob