I keep an adapter cable in my car for charging my cell phone from a 12 volt outlet. But all of the 12 volt outlets in my car are switched, i.e., dead unless the car key is not off. Even the car's battery won't last long when the key is not off.
(a car with GM's OnStar or LexusLink would answer a call for 30 days at least,if anyone thinks to try it. But this was a Honda Element)
This finally nudged me to order an AA charger for my cell phone (I already carry a set of Lithium AA in the car for the GPS). My call phone charges from a USB cable so I got BoxWave unit that takes 4 AA and has a USB connector to charge from.
PS. 7 days seems to be the standby time most marketing types want to claim, and the engineers often come close in good conditions. But she was well below terrain after the fall and covered by brush, and she was on the way home so when was the last full charge?