alternator/battery question

[bloody_angel111]

Well my battery is only 5 months old, pep boys battery, and I just had my alternator replaced about a month ago, since I was told it was bad, and the one I bought was used, but was supposedly tested before being sent to me, from an ebay seller, and the first weekend it was on, I didnt drive my car, and monday when I went in to go start it for work, the car cranked once, and was dead, and battery was showing under 9v, so i jumped it that afternoon, and it was fine.

That afternoon, I took my car to walmart to have them check the battery and alternator, and the guy told me the battery was bad, so I took it back to pep boys and had them test it, and they said it was good, so im confused here? The problem is when I start the car in the morning, its only showing 13-13.5v on my SAFC, and after driving for a while, it gradually gets lower and lower, sometimes even into 11v, and the car starts running rough and idles low, and I dont know what the problem could be.

I didnt install it myself, I had my job do it, but i dont know how they could have did it wrong, and the belt is tight, I just put a crank pulley on, and made sure it was tight, but that didnt help nothing, and checked the 120amp alternator fuse, and its fine, so what else could be draining the battery like that?

 

[VapedTalon]

Do your lights pulse at all when the car is acting funny? Both my car and a friends car didn't even have proper grounds to the alt. It caused all sorts of issues such as battery not charging, idle surging, lights pulsing. Make sure that the ground has a good connection.

 

[bloody_angel111]

Thanks for replying. Ive never really messed around with my alternator other than changing belts, so I really dont know what to look for when checking for a proper ground, although i do have a ground wire kit, and have a wire grounded from the negative battery terminal to the alternator itself, so I would think its grounded good, but maybe im wrong?