I have noticed for a long time that my 1995 Suburban doesn't read as high in voltage as other cars I have owned. It shows 14 at the absolute highest and is on the line between 9 and 13 if I am running a lot of things such as front and rear fans with the radio and the lights on. All of the other Chevy vehicles I have owned have run between 13 and 16 all the time. I have replaced the alternator and the battery but it hasn't seemed to change anything. in my experience with other cars I have never seen the volts so low yet the car still starts. What is the chance I have a bad volt gauge?