Ford Repair Questions? Ask a Mechanic for Answers ASAP
Hi there welcome and thank you for the question hope i can be of some assistance to your problem
This is quite a common problem with vehicles with twin batteries and it is always the front aux battery that does this as it gets the most use, it is actually the battery itself and is caused by a short of the plates inside the battery which causes the battery to get hot and the smell is produced from the acid overheating smells a bit like raw eggs to most people.
The only thing you can do for this is to replaced the battery and to check the current draw on the battery should not be above 0.05amp max after everything has shut down normally takes around half an hour to drop off.
If your vehicle is a 2011 build as it says in the information you have filled in then it should be still under warrenty so i would have this checked.