Crazy (not) charging problem on my 68...

[TommyShameless1978]

Okay, so my car has been running like garbage since I got it all back together. I quickly noticed that the charging system wasn't functioning, even though everything was new. I decided to go pick up a new voltage regulator, since I had problems in the past with the one in the car. I picked up a unit from NAPA.

Here is where I did something I should be smacked in the mouth for!

I got home, started up the car again, and stuck my multi-meter on the battery. 12.7-ish, no change at all from when the engine was off. Okay, ready for this? Like an idiot, I PLUGGED IN THE NEW REGULATOR WITH THE CAR RUNNING. Immediately, my charging system worked again. Except it was putting out almost 18 volts at the battery. I placed it on the firewall, put the first bolt through, and voltage at the battery came down immediately to 14.5-ish. Bingo! Now we are in business! Mind, you, the car is STILL RUNNING. It was at that point that I noticed the first flash from behind the regulator. And the meter dropped into the 13's. And another flash. And it dropped to the 12's, exactly like it was before. And the smoke came out of the regulator.

So, I started cursing my own stupidity, thinking I must have shorted out the regulator by allowing one of the terminals to get to close to the firewall. I desperately search for another one, and find one at Auto Zone. It looks different...same configuration, but all silver, not black like the one from NAPA. Also, it is made in Mexico. I put it in, and there is absolutely zero change. So, I start wondering what the hell is going on. Did they give me a bad regulator?? Well, wanting to narrow thing down, I took an old alternator off the shelf and threw it on. Same problem. So I took that alternator and the newer one that had been on the car up to Advance Auto Parts to have them both tested on their machine. The old alternator failed, but the newer one, that had been on the car, passed. Hmmm...okay, so I bought ANOTHER REGULATOR. This one is like the NAPA unit that had briefly functioned this morning. I put it on, and my tested good alternator, and I still have nothing whatsoever. I have 12.6ish at the battery, and 12 volts at the large lug on the back of the alternator.

I also have 12 volts going into and out of the regulator...slightly less than what is at the alternator, but still 12 volts.

Now, here's what is crazy (I think). I am using dual-field alternators and just grounding one of the terminals (yes, you can totally do this). I've never actually checked what those terminals would read, but I did just now. Both are showing ground when I use my power probe. Strong ground, actually. In fact, with the engine running, they still both show ground. I even disconnected the one that was grounded, and the other terminal STILL shows ground. Even with BOTH terminals disconnected, they both show ground!

What do I have here guys? A bad alternator? Is it internally shorted? How could it have tested good on the machine at the auto parts store then? And is it taking out my voltage regulators? Or did my stupid more this morning fry out my new regulator AND kill my alternator?

I'll be up all night with this one!

Tommy

 

[bigmanjbmopar]

Wow long night, Sounds like you fried the regulator is the resistor installed? With out the regulator installed correctly I would not try to trouble shoot the ALT. unless you know it's bad. With the battery disconnected replace / remount a known good regulator then start it up get it reved up to 2k rpm and check with meter.

 

[Ron 73]

While i was slowly typing bigmanjbmopar made some good suggestions, but ill leave what i wrote anyway in case it could help... Hope ya don't mind bigmanjbmopar i type slow, hate to waste the effort

Sounds like a mess for sure, I would start where the voltage reg is located Take it off and make sure there is no corrosion at all there, no rust, clean.... Then make sure its a good regulator and the right one for it, and ive seen guys put the wrong ones on, sometimes we get in a hurry along with just plain fed up. If the alternator is testing right, the voltage reg is correct and clean, believe it or not so many of these problems end up corrosion and rust. Then check everything, grounds, plug ins, look for any burnt wires, cracked or broken ones. This is kind of starting at the basics, but ive found its the best way to start. Do you have a voltmeter or amp meter in your car? Check the connections, tight and not touching anything back there. Somewhere here i have a test that you can use to check everything with a volt multi meter that ill be glad to post if you want it. If none of this works there's other things to check but this is where i would begin, just a suggestion.

 

[bigmanjbmopar]

No worries! I yield the floor lol

 

[TommyShameless1978]

Solved!

The field wire going to the regulator had a bad terminal end connection, AND one of the wires on the OTHER side of the regulator had a dead short!

My suspicion is that...well, actually I haven't the foggiest idea what took out what or why or how. I just know that it works again!

Tommy