I had this happen a few weeks ago. A little research here showed others having this issue and it ended up being a bad voltage regulator - a 'known' issue that is covered under warranty. I went in and had it looked at and they replaced the entire voltage regular and associated parts. While there they also diagnosed a funny noise in the primary (which I didn't even hear/notice) and they replaced that as well, also under warranty, also a known issue. My warranty is up in two weeks - or it was going to be... I just reupped if for two more years!
2013 Road Glide Custom CVO in Roman Gold/Burnt Emerald, Le Pera Maverick, Vance & Hines Power Duals, SERT, MadStad 13", Kury ISO grips & Scythe mirrors.