Loose ground wire?

I have a 2011 5.7 and theres a nice whine coming from the enginge bay. Sounds like passenger side. My battery voltage will run low and windows will roll very slowly (sometimes) and sounds gets worse when windows go up. Truck didnt start the other night and out of anger i punched the steering wheel then it started. Batterys only 7 months old and no lights on dash. Could it be a loose ground? Hoping not the alternator

 

Wine usually means bearings or other rotating mass noise. That would suggest the alternator going out, especially with the other symptoms you describe.

 

Put a voltmeter on the battery while the truck is running. If you measure 13.5-14v the alternator is charging. If only 12v it is not charging.

Try to listen closely to where the wine is coming from. Old school guys will use a long socket wrench extension or similar to stick on the metal part of alternator or similar. The solid steel will carry the sound better and you can hear it if you stick your ear close to the open end of the extension. If that makes sense

 

^^ What these guys said. Pretty simple and easy to rule out basic alternator problems with a multi-meter as instructed above. Whine could be a different part of the belt drive such as a tensioner or pulley and be simply coincidental, but could also very easily be the alternator itself. With the information you've provided, I would suspect the alternator before a loose ground wire.