There was a service bulletin on 2012 bikes due to bad voltage regulators. Mine was replaced earlier this year under warranty.

 

Mike, Harley replaced my voltage reg. today on my 2012 FXDC. While riding the Alt. would quit charging and then start back. ( I have a RG Fairing on mine, and a Volt meter) The charging Voltage would vary from 12 to about 14 while running about 70 MPH. Then it would go higher and stop charging. I rode it to the Dealer this AM(about 38 miles) They carried it in the shop to test and it would not start. Charged battery and
cranked to test Alt. output. They said Reg. was bad. Installed reg. and tested, told me I was ready to go (no charge) Burned a full tank of gas before I got back home. Running great.