My car for the past month and a half has been dropping more and more in voltage. Right now it sits about 1/2 way in the yellow. I was thinking it was just a bad alternator but when I disconnect the cables and reconnect it will come up to about 1/2 way for a few hours. Please help. Thanks.

 

the little black or red cable (depends on car) that plugs into the top of the alternator could be bad....this cause the alt. not to charge and will kill your battery slowly....ive dealt with this issue personally before

 

^agree^ check underneath the red and black rubber boots for corrosion. Common problem.