Hi All. When I am on the highway at high speed the voltage gauge keeps bouncing low every few minutes. If I cruise at a lower speed it stays steady. Also if I punch it to pass someone the lights will dim way down and the battery icon will light up and I get a message "battery not charging". When the rpms come back down all is normal again. Anyone have this experience? Thanks

 

so... is this the impala? Tahoe? Ram? year/make/model would help

 

Sorry, 2003 Suburban.

 

First make sure the belt is tite. Even if it's a serpentine, the idler may not be as stout as it was when new. Second get the alternator tested. Most auto parts stores will do that free.

 

Absolutely correct. Check the belt and tensioner. The belt may be slipping and that will cause the low voltage on hard acceleration.

 

Thanks. I changed out both belts, idlers, and alternator last year. I'm gonna try another alternator.

 

Put in a new alternator, problem solved.