My Volts Gauge goes down to red line at idle and bak up when im driving. I had my alt. tested today and they said it is working great. I had my battery tested last week and it is fine too. They did say that it wasnt fully charged though. If my car sits for a week without a start the battery will be dead. What could the problem be? Both my power windows dont work either. Could both motors have failed or does it have to do with this problem? They go up and stop and then go up more in time.

 

Upgrade your battery cables.

I had the same problem.

I had a huge battery and a 124 amp alternator.

I upgraded by power and ground cables to 1 guage and it cured alot of it.

 

It's most likely the pulleys... if it just goes down at idle[in gear?] it's not really that bad... mine does it .. I pop it into neutral at long lights etc.. never really had battery go down yet...
Battery 'going dead' in a week, you have some sort of parasitic draw there, it appears..

 

Battery 'going dead' in a week, you have some sort of parasitic draw there, it appears..

How Do I fix that??