txjeeptx & mernsy,
That's a common misconception. Cessna, and in fact all general aviation aircraft run off either 14v or 28v different models use each(there are rare exceptions, but they are like the early bugs that ram 6V, an annomoly). The 14v system is actually the same as an auto system, as the alternator is typically rated at 13.8V-14.35V(there are LOTS of old Chrysler & newer Nippondenso alternators on GA planes).
In the aviation community they refer to the running/charging voltage whereas the automotive refers to battery voltage. The 28v system is usually a pair of 14V in series, though 28v batteries do also exist, and the alternator is just regulated differently & has more windings.
Doc
(Pilot with somewhere well in excess of 3000hrs in the left seat)