Martin #1458 & #4427
I have a Sears "Security" Die-hard battery which shut itself off if its voltage drops below a certain level (around 10 volts), in order to preserve enough juice to start the car when I return (in case of the low current drain many of us experience). It's a great feature - I only drive my car once a week or so, and the battery is always charged enough to start the car once I reset it with the key-fob remote.
I also have a new Alpine radio. As you can suspect, each and every time the batter turns itself off, I lose all the settings and presets, and there are alot of them on this head unit.