Thread: lights dim at high rpm

my lights are dimming when at high rpm ,over 5,500. battery is staying charged, engine runs fine.
i was following my son on his ss cobalt, and we both hit it and after 5,500 rpm they started to dim.
is there a way to check the alternator at high rpm's?i'm thinking maybe a diode is going bad or the
rectifier.there are new gatorback belts on alternator and supercharger,thanks,jimmy

i'll double check them tomorrow,maybe i missed something somewhere.thanks redcompg.

How old is the belt tensioner? I've had this issue with cars in the past at higher rpm's where it would let the belt slip as well.

don't really know fordman77, i thought about that too.i guess if its that old it needs replacing. i know as soon as i let off the lights brighten again, almost instantly.