I have a 2006 F250 diesel and last winter when i plugged the truck in my power bill over doubled..meaning the truck used for electricity then everything in the house..any ideas on the cause of this because the 2 winters before this i had no problem

 

The block heater is a really simple system, it's a heating unit that is stuffed into what would otherwise be freeze plug hole on the passenger side. Maybe the heating element is bad.