My dash volt gauge reads almost 14 volts while running with my a/c on.... but when I slow down to a stop my volt gauge dips to around 12.. 12.5.. but not always.. but most of the time it does.. once I step on the gas a little it climbs back to almost 14 volts.. is that normal? I had a new alternator installed about 6 months ago... and I put a new battery in the other day to test to see if the battery was the problem, but it does the same thing with a brand new battery... I just dont know if that dip when coming to a stop is normal or not.. and if not what can be the cause..

thanks