Thanks for the feedback. I actually contacted Zamp and herd back from them the very next day…great service. They said the controller is functioning fine. The 15.5 volts is actually meant to happen to burn off sulfates if I remember correctly and is usually momentary. But that voltage should never reach the electrical components, only the battery and the battery can’t put out more than it’s rated voltage. So, more than likely, Host wired the solar controller right into the electrical grid and not just the batteries like it should be. Now to deal with Host. I’ve had other issues with this camper and Host is less than helpful.