Makes sense about the coins - I hadn't thought of that being a possibility.
While we're talking about these sockets: I would like to keep my USB plug in the socket when I'm not using it, but the socket is powered when the key is off. Does anyone leave theirs plugged in (without anything else plugged in) and it NOT drain the battery?
I unplug mine just for the fact that I don't want to take a risk on draining the battery, I had enough charging system problems as it was. All these new cars draw some milliamps when the car is just setting, it shouldn't be enough to drain it over a few days, but if you let it sit for a few weeks don't be surprised if its dead.