So I let my car sit for about a month. I went to take it out yesterday and it was completely dead. I charged it for 30 mintues and everything was fine. After driving it for a while i noticed everything started getting dimmer and my voltmeter was getting lower. Eventually nothing electrical would work on the car, I couldn't even put up the windows but the engine was still running perfect. Could this be an alternator problem? I just think its odd how nothing would work but the engine I let the car run for another 20min and it kept running strong.

edit: Once I shut the car off, it had absolutely no charge at all, couldn't get it to even turn over. God damn remanufactured alternators

 

try swapping batteries from another car first, then try changing alternators. Its also possible you might have something draining the car but its hard to say.