the regulator inside the alt is usually the problem when the alt is draining the battery. take the alternator in and have it checked just to make sure when u buy a new one. take a minute to make sure its not the switch. hook the main wire up to the alt and unhook the little wire. with the key off there should not be any power getting to that little wire while its unhooked.

 

Well, im not an electrical guy, but logic says, have them test it at an aoutozone, and if it's bad, get a new one.

 

Try getting a better battery that has more charge/discharge cycles like an Odyssey (I'm told the US Military uses them), read:
http://www.camarohomepage.com/project/part4.htm

But yea, get the alternator tested -- Murrays auto parts does the check for free.

 

I just recently found what was doing the same thing to my 87. While I was looking I disconed neg cable overnight.
Rear hatch mech. Hotter than... you know. Powered even when ign off. Look into elecs items like that.

 

ignore posted on wrong page

 

I had a problem similair to that, just make sure first of all that you have a big enough battery because I bought some dinky little one from auto zone and it would kill it almsot immediatelly when I started it. and then get your alternator checked at autozone or something and if you're still having problems make sure that it's not some dumb little thing liek your radio or a door light.