Lose of power

I have recently purchased a 2005 SL500 that had been seating in unheated storage since 2010 with the top down. I didn’t even try to save the batteries I just replaced them with new ones from the dealer. After clearing a large amount of codes from seating so long, I’m down to just two that seem to have nothing to do with my current problem. An Ac cycling switch and a Vario roll bar positioning fault. After the car sits for a couple of hours the battery totally disconnects from the car and shut everything down and makes it forget what in its memory and makes it unable to unlock the doors or open the trunk. But as soon as I place the key into the ignition and turn it twice everything jumps to life and the car will start, but it acts like the batteries behave been disconnected and then reconnected it has no memory of what was stored. I have replaced the starter fuse and the relay in the trunk and placed a drawn down tester and still have no idea where to go from here. No red warning lights on the dash and no new codes that would lead me to believe anything more then a lose of power after it sits. Any help or direction would be greatly appreciated