Headlights Dimming

I have been having problems with my headlights dimming at an idle. The second i kick up the idle or accelerate, the lights brighten up. Also i had an elecrical problem before, my negative ground cable for my battery was sh*t so i bought a new one. I also bought a battery thinking that was the problem before i found out it was the ground. The battery was never being fully recharged. Could this possibly be a problem with my battery? Or this alternator related?rock and roll!!

Hmmm, in my experience, there are so many things that are related to this: 1. Battery 2. Small alternator 3. Small power cable for your amp 4. Maybe you need a capacitor Well, this is assuming that you have some sort of audio system, which you didn't really mention. For my problem, I added a 1/2farad cap, and a larger wires for my amp's power and ground. The wires helped a lot (I did them first), and the cap seems to help somewhat. I still get the dim if I'm at a light, but not as much. ALthough I've heard my alternator is a weak one, so I'm sure that doesn't help. I've heard, too, that if you do this too much (dim), or put too much of a strain on your alternator, then you run the risk of hurting it.

If I was you I would think about getting a higher output alternator.  What kind of car do u drive and how much power are you driving with amps and such?  If you are running an amp or two, I would think about a new alternator.  Do they stay dimmed or does it kinda go with the bass hits?  We will need more info to get a good diagnosis.1 plus 1 equals 2

Ha Ha. I don't even have an audio system. I am just having the problem by itself. I guess i should have said that. Anyways this is an old cop car. So from what i have hear they have a larger alternator to run all the lights and all that other sh*t. This all happens simply at an idle.rock and roll!!

i would check all your wires comming off the batt. i would also run 1 or 2 extra ground wires from your batt to the chassis. what rpm is your idle set at? some ho alts don't start kicking the power untill 1000 rpms. check all that stuff before you spend money on a alt.Big Dave

some cars its normal, at idle my 93 subuaru lights dim, heaters slow down pretty much evertyhing drops, it also don't help my car idles at like 250-300 rpm, im dead serous it does, only thing u can do is may adjust the idle speed

you could also adjust the pully ratios on your car. all you would need is a smaller pulley on the alternator, and a new serpentine belt. you would also need to calculate what it would be doing at idle to get the right one. and if it revs really high you mught not be able to go as small as you want because the alternator can only handle so much. but first i would go to an auto supply store, and they will probably test you electrical system for free. they will tell you what wrong. make sure your battery has been fully charged before you go, if you want the right readings.