I left my headlights on in my PT Cruiser. Battery completely dead I put the battery charger on and got into the car in a couple minutes to put the window up since it was about to rain. The radio was on and all buttons displayed 750 AM. I knew it lost the settings. But when the battery was charged and I went to program the radio pre-sets, they were all back to where I had them. What held the settings? This battery was dead!