Not seen the wiring diagram for a 2008 car, but the socket itself ought be fused at a fairly high rating.
If the battery charger does not have one, easiest thing to do is put an in-line fuse and holder in the lead from it to the car. The book of words on the charger ought to give maximum output, and the fuse needs to be rated a bit higher. Example, if charger supplies up to 3 amps, put a 5 amp fuse in.
