Help! Battery wont charge.
 

I recently got a 92 Mazda Protege 5 speed. When I'm driving (mostly at night) my charge light will come on and after a few minutes the car will die. I replaced the alternator and battery and have checked all the wiring between and everything checks out fine. I took the alternator back in to be retested and it passed pushing out 14.6 volts. When the alternator is on the car and they test it it fails every time. Coming out of the alternator I get between 11.8 and 12.6 volts depending on if I'm running accessories. I have no idea what to be looking into next any help is appreciated greatly.

Clean your grounds. Check the connectors on the harness for any corrosion (look inside of them).