alternator overcharging

[MatthewGoff]

I was driving to work this morning and about 5 minutes in check gauges came on and my voltage gauge was pegged out. should i bother with taking it off and testing it or is it shot? most of the winter it was overcharging a little and it worried me but always evened out. also bought the truck with what appears to be a deep cycle marine battery, pretty hefty looking SOB. it has also been dying on me when i let off the gas to put on the brakes and it will die while downshifting. dont know if it could be a related issue.

 

[MatthewGoff]

took alternator to auto zone and tested good, battery at 12.53. theyre trying to sell me on a new battery but this alternator looks like hard hammered **** with grease all over it.
220,000 miles on it its probably bad.

 

[Cowboy770]

I don't use autozone anymore due to same type of issue but with a starter .They told me my starter was good but bought a new one and problem went away .have both alt and battery tested at another place .