Ladyshires

On the hour counter, lower hours = higher trade in value, we all know that. What if the key is left on and it drains the battery - is the counter powered by a separate source and will it continue to click away in spite of a dead battery? Seems odd that it would, but someone has told me that since the key was inadvertently left on for several days, the hour counter has racked up several days worth of hours.