Since we got the prius in October, I have noticed that the lighter socket won't work properly. I have tried multiple chargers and some work, some don't. The ones that don't work in other cars just fine. My theory is that the plug is too shallow for the socket and doesn't make good contact. The one that doesn't work looks like this:
Try extending the contact on the end with something. Maybe solder a small piece of metal to the tip or maybe even just a gob of solder will extend it enough to make contact.
