I own a 2004 VW Beetle and I have been having the same problem summer after summer- it randomly dies! I bought a new battery, and have brought it into multiple mechanics (who have kept it for weeks at a time) and no one has been able to figure it out. I make sure no lights are turned on, I turn the radio off but it still dies. Sometimes after one day, sometimes after a couple weeks.
I mistakenly bought this too-cute beetle because of the flower vase and blame my bad luck the powerful force that is Ford Karma- my dad works for Ford Motor Company and has for the past 30 years… should have bought a Ford 
It know its ancient history, but I have not thought about buying a VW since the 1970s.
Your post tells me I am not mistaken.
Why do you believe that it is a battery problem?
Have you had the battery and charging system checked?
You say it randomly dies. Does it start back up? If not, what do you have to do to get it running again?
What exactly happens when it “dies?” Does it just suddenly and without warning die like you turned the key off? When it dies do the gauges, and lights go out at the same time? Can you start it back up right away, or do you need to let it cool off???
Feel free to add anything else, even if you don’t think it is connected.
Does it only die after warming up? Does it only die when cold?
INFO we need INFO…
It is a little cryptic reading through the problem, it sounds like die means dead battery after sitting and will not start. Let’s start with the age of the battery, and go from there.
More info…
I bought a brand new battery last summer (2009) when my friend thought that might be the problem. After getting it installed, and again, having the car die (by die, I mean, it’s dead. no lights turn on, no engine sound when I turn the key- nada.) he took it out and got it tested. The battery tested out perfectly.
When I took it to the mechanics- a couple of them- they did all the testing to see what was draining the battery and couldn’t find anything.
When it ‘dies’ I can easily fix it by getting a jump and everything starts up again and it’s fine to drive. It doesn’t die when I drive, usually takes a couple days/weeks and often when I leave it overnight.
I thought it was solved two summers ago when I had my headlight replaced (in the new beetle, you have to replace the lightbulb by removing the whole component and taking the bulb out from the back, the original owner must of had someone pop the lens to replace it, and then the lens cover fell off. the headlight is in front of the battery/electrical in the car and when it would rain, car would die. When I got this headlight replaced, it helped for a while but then the car would die again, rain or shine.)
I don’t use my car that often, in the past 3 years I’ve put 20,000 miles on it, and mostly driving back to Michigan (700 miles round trip) or Chicago. Daily, I ride my bike and there are weeks where I might use my car just once or twice.
Thanks for your help! I really appreciate it!