Two months ago I had an alternator wire break,the factory crimp was not centered on the connector and the crimp almost cut the wire,over time with the vibration and heat the wire broke at the crimp,the dash light came on and I started the generator which charged the bus batteries,it was night and I was only 15 miles from home.I don't know how long the Guest charger will power the coach with headlights on but I doubt that it would supply enough current for several hours at night.I had a regulator fail last spring and I had to drive 3 hours and the Guest charger overheated after about 2 hours and shut down,I had another charger with me and hooked it up and made it home.