lights dim at high rpm

[1fastam]

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

 

[REDCRAPGP]

Check and clean all the grounds and power wires.

 

[1fastam]

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

 

[FordMan77]

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.

 

[1fastam]

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.