dumb question!!!

only time i had this problem was when i bought a car, it would do like described above. found out after taken the car for a 15 minute cruise, the dummy before me had put a dual lead alt on a car that only had one grn and one led off of the alt. so at idle, it would not charge, but once i got the car moving, it was seriously over-charging, and i could smell wire burning under the dash.
so, like a jack ***, i thought it was the guage in the car, so i cut it, and tried touching them together while at idle, and there was no spark. then i decided to hold the throttle at like 2500, and then touched them together......... it was like ark welding under the dash, it literally burnt the skin off 4 fingers, and the two wire ends basically fused together,lol what a jack-arse i felt like.lol