i drove it for aday and it died on me... i changed the alternator and still the same, not charge while engine is running (staying a 12.46 volt and dropping) i changed the battery and still the same. what else could it be?

did you wiring the alternator correctly? check if there are any loose wires.. and check if you ground everything correctly check for tightness..

Yeah, the alt should be able to keep the engine running w/out help from the battery. Double check your main wiring connections.