Hi I just got a 82 Toyota pickup the other day. Well yesterday I was out at the lake turned it off for about 10 mins went back battery was dead. No biggy i just bumped started it drove around for a couple mins until my friend got stuck in the mud. I left my truck running prob 15 mins came back to it and it was just getting dark turned the headlights on supper dim and than just went out. tried to leave on the way out just died no power. Basically I knew the alternator was crapped out so i replaced it today and put a good battery in it haven't drove it yet but started it and charge lights still on? What could it be? PS the light was on sense i got it prob 2 days before this happened.