We have a 1999 Safari Serengeti with a VMS II. When starting the coach the voltage guage goes to 14 and the VMS reads 14.1 volts. When driving the gauge stays at 14 unless we are using lights, the VMS reading on a flat surface is usually around 13.5 to 13.9 volts, but when you start climbing a hill or putting a load on the engine the vms volts start to drop. Pulling up a steep hill the VMS will go down to as low as 12.4 volts even though the rpms are at 2000 and the gauge is still at 14. Which reading is right? Thank You Don