Alternator won't charge. What do I do?

[wagon]

Well, I was coming home from work and my 87 GN was sputtering. I figured that the gas gauge was broken and I was out of gas. It wouldn't restart. It turns out my battery was dead. I didn't get the alt. light or anything, but the dash got dim (digital). I put on my battery pack and the car starts right up. When I take it off, the car just dies. Bad alternator, right? That's what I thought, but no light. I changed the alternator with one that I had on the bench from my waGoN that is currently apart. It still won't charge. The waGoN's alternator worked fine when I took it off, and still no light. So, I'm guessing maybe the bulb is out. Nope. Now I remember that I have another alternator in the basement. It has been there a while, and I don't know the condition, but throw it on anyway. Still no charge. The car runs until I shut off the battery pack, then it sputters and dies, my voltmeter reads about 12 while the pack is on, then drops to 7 when it is off, and the car dies. This is with 3 different alternators, the charge light never comes on even though I checked and the bulb is good. The single wire is plugged into the back, and the wire from the battery cable is connected, and does have 12v at it. with the batterypack on. The neg cable is attached securely to the head. What can it be? I'm stumped. Thanks in advance.

 

[wagon]

Well, I knew I should have searched for the solution first, but I wanted to get this fixed right away. Anyhow, here is where I found the solution.
http://www.turbobuick.com/forums/showthread.php?s=&threadid=124102&highlight=alternator+wont+charge

I turned on the key and only the seat belt light lit. I pushed on the bank of lights on the left side, and a bunch of lights came on. I started the car, shut off the battery pack, and the car is charging hgih in the 14s. All that alternator changing for nothing.

 

[TurboBuckeye]

That's good info to have

 

[Red Regal T]

Look how good you are at changing alternators.