well i just put a 408 stroker in my 98 SS and the battery is not getting any charge, i just replaced the alternator and its doing the same thing. Last night i let the battery get a trickle charge all night and when i started it, it was just below 13 then it came down as i drove it about 15 miles and then died on me. I have a brand new red top optima battery so i know thats not it. Any ideas guys? I need help asap!! thanks if anybody knows what that little wire is that goes to the plug that goes into the alternator from the wiring harness that would be help full. thanks

 

That the little wire is probably your sensing wire. That should be getting voltage with the ignition on. If there is now power going to that wire the alternator will not charge the car.

 

+1 that wire tells your alternator to charge the battery.