Ever since I had my fitst C5 in April 1997 I have had nothing but trouble keeping a charge in the battery if the car sat for 3 weeks or more. My 1998s, 1999, 2000 and EARLY 2001 were no better. Now I have a late production 2001 and have NO charge/battery problems at all. My car sat for 6 weeks and I put the trickle charger on it and in 2 hours I had a full charge light to my amazement. What ever was wrong/draining the C5s battery is now gone and fixed. To bad it took GM 5 years to decide to fix it.