I'm having some trouble with the battery in my wife's 2004 Jetta. The battery was purchased in November 2009, making it about 2 1/2 years old. The problem is probably best described with a no-so-brief timeline of events, all of which took place over the last week.
Wife takes the car to work at 7:45am (about 3.5 miles away from home, about a 10 minute drive). She goes to leave at around 4pm and the car won't start. She calls me at work immediately (as someone has to get our daughter from day care by 5pm) and I pick up our daughter then drive to where she works. I take them home (our 6 month old was getting cranky) and head back with our Passat to jump it. It takes about 15 mins to charge, but ultimately starts up (everything was completely dead, no clock, odometer, power locks, etc.) My wife swears she didn't leave anything on, and I believe her, but she and I both understand that she could have easily left something on and just didn't realize.
I take the car to Sears (about 5 miles away, 15 mins with traffic) where the battery was purchased, figuring if I need a new battery, I might as well just get it overwith that night. They test battery and alternator and both are fine, so I take the car home. I start it up one more time around 10pm with no problems.
As the Passat was still at my wife's place of employment, we take the Jeep together to drop daughter off, then I take her to work so I can get the Passat. I leave the Jetta home all day and try to start it again at around 7pm. It starts without any hesitation whatsoever.
I take the Jetta to drop my daughter off at daycare (