I have a decent sound system in my truck, when at a stop the lights dim when the bass hits from a song. I am looking for a bigger alternator, in my search I really only find overwound ones. If anyone has any leads that would be great. Thanks. ( I know I will most likely need a different belt)

 

Welcome from Florida. What is the amp rating on the alternator that you have now? You can also put a smaller pulley on your alternator and that will make it spin a little faster so at idle it puts out more.

 

I have the stock one which I believe is a one twenty

 

Welcome from WA - my dear departed mother would tell you to turn down that darn music!!!
When sitting at idle, what's the volt reading at the battery using a multimeter?

 

How old is your battery and have you had it load tested to make sure it is not going bad?

 

It's not my battery. I am looking for a bigger alternator not an overwound one.

 

if I remember it was at like 10 something, not going to kill the truck but not helping the situation out any.

 

So that shows you are not getting a charge at idle. Does it jump up to 13.5v or greater at 1000rpm? What's your battery voltage motor off after sitting overnite?
If battery is not new have it tested; could be part of the problem

 

if no big bass is playing it fine as soon as bass its voltage drops, no problem charging if no major bass is playing. But still i have no problems with it keeping a charge, want/need bigger alternator for the longevity of my battey/trucks electrical system life.

 

what is your idle battery voltage with the stereo off?