On the back of my Bro's 87 Camaro LT alternator it has a post labeled "BAT" and it was hooked to the negative battery terminal. Isn't this for charging? Shouldn't it be connected to the positive terminal? It also has a splice off of it heading somewhere under the car but i'm not sure where it goes.

We took this off and the car started just fine w/o it three times in a row (It wouldn't before w/o a jump) but I'm not sure if it's because I removed that wire or just because we let it sit for a bit.

With the wire off and the car running, the alternator wasn't putting out any voltage by reading from the ground to the "BAT" terminal. I'm guessing if it was hooked backwards, the alternator is fried.