Chevrolet Repair: Tahoe slowly dies then restarts and rides fine then does the same thing, chevy tahoe, battery gauge

Question
1999 Chevy Tahoe!  I am extremely curious as to why the Tahoe starts fine and the battery gauge is at normal 14 voltage, but after riding for 10-15 min the gauge slowly lowers and almost dies (has died once).  When it gets that low, if i pull over and put it park the gauge moves back to normal and drives fine...then if i am driving long enough it does it again.  The temperature gauge does not read as if it is overheating, but when i pop hood i smell traces of anti-freeze.  So i have no clue if it is overheating, if it is electrical, fuel pump...i just do not know.  Can you help me out please

Answer
Hey,

 YOu need to have the charging system tested.  IF the gauge is accurate your alternator is failing when it gets hot.  Don't trust the gauges though because they chronically tell the wrong info.  Have it tested with a voltmeter and make sure someone pressure tests the cooling system.  There is multiple places that can leak and if you run out of coolant you will be kicking yourself in the butt.  If you can smell coolant that because its coming out of the system. Sometimes when the cap vents into the reservoir you can get a whiff but not usually.

w