Duralast Inverter

I have a 5th wheel with 2 gel cell batteries and an inverter installed in the basement. We were in a Forest Service campground with no hook ups so I was going to plug my cell phone charger into the inverter but decided to plug my voltage meeter in first to see what kind of voltage I would get. Ouch it was putting out 130 volts. I do not know if that is just a fluke or if it does that all the time.....