When I go backpacking and park my 2006 prius at the trailhead I disable the Smart Key with the under-dash button and leave the fob in the car, taking only the small physical key in my wallet. I'm afraid the fob could be lost or damaged on the backpack. Now with my new plug-in, I don't see a way to disable the system so I can lock the fob in the car. Am I missing something? Anyway to do it short of removing the battery from the fob?