Parasitic Draw
 

Bought 2011 Elantra Touring from dealership. Soon after car would not start due to drained battery. After several trips to service department they determined battery leaking electricity to audio system. Diode in radio head staying stuck not allowing unit to go into sleep mode. I had them disable audio system to stop leak. Solved problem until I left car off for 4 days while away. When I returned again battery was drained. Using Ohm meter and pulling each fuse traced leak to Memory fuse. Pulled out part way and leak stopped. Pushed Memory fuse back in and still no leak. Service tech thought might be temporary fix. Before I spend $450 for after market radio I wanted to make sure I was not going to make problem worse. Not convinced have really found the true underlying cause. Any ideas?

1. Yes, the radio power drain is a known issue.
2. if you do leave the car sit unused for 4 days, I would suggest pulling the memory fuse anyway. Modern cars use electricity even when turned off. Long periods of no use will drain a battery.