When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Doesn't hurt to check for excess drain as DeeGee suggests but it is VERY common to find your battery dead if you do not drive the car for two weeks or more (obviously!)
There are many electrical drains on the C5 that suck the power out of a perfectly good battery and even a very good used one.
Your best bet is to use a battery tender if you do not drive her once a week or so. They're simple, easy and safe to use.
A battery tender is simply a 1 or 1-1/2 amp trickle charger that runs as needed and then when it senses the battery is charged, goes into standby mode until more charging is needed.
Lots of threads on these.
I have an 01 and a new battery will go in this spring along with my spring maintenance. It's common to have them replaced every 4 or 5 years. Like the others said, they pull a lot of power simply sitting there. There aren't many of us that don't use a battery tender, very easy and safe.
Vinnie
I have a Y2K, no dead battery issues. In fact had the car in the garage for 2 months straight due to knee surgery and she fired right up last weekend. But I do agree with the preivous post for the battery tender or a trickle charger. It will maintain the battery charge and extend the life of the battery.
I also have an 01. It sometimes sits for a week or two between drives. I go out into the garage and can sometimes hear the seat pump operate for a second, pumping air into the air bag I presume (I may have a leak). It does this a couple of times an hour. The computer also takes power. I also have an aftermarket alarm system that has LED's in both front and back that blink all the time, so my battery is constantly draining. I just put a battery charger on it every few days and charge it up.