ron fish

Jan 21, 2012
2002 coupe
Hi everyone. I recently sold my 02 C5. In 4 yrs I got thru 3 batteries. I was told these particular models were notorious for battery failure if the car sits for greater than a couple of weeks or so. It appears there is a considerable "parasitic drain" on the battery due to the fact that there are numerous electrical circuits that drain the battery when the car sits idle. I am considering purchasing a 05/06 C6. I would like to know if this model suffers from the same problem. Thanks.
Yes is the short answer .It's a great contention of what to do and I can only tell you what I do .If the car is going to set ideal for a couple weeks I hook up a tender .If the car is going to set for more then a couple months I disconnect the battery .BUT if your going though a battery every year than there are issues somewhere .I replace my battery about every three-four years and that original equipment spec.
C5/C6 Electrical

Tks for the reply. Any thoughts on what areas to check for the power drain?
Hopefully someone should be able to properly answer this but I believe if you put a C6 in reverse gear when parked, it doesn't drain the battery. Not sure what the guys with auto's do......

Not too sure where to check for power drains on these cars. I imagine one of the best solutions would be to start by cleaning all the grounds and connectors as this may lead to causing extra draw.
I've had my car for three season now and not one bit of trouble. I think the best advice is to buy either a Red top or like mine a Yellow top optima battery. Last year I was away for a month and accidentally left my radar detector on and came home to a totally dead battery. Put my C-tec on it and within 2 hours it started right up. For winter storage I just put the c-tec on and forget it. come spring it just starts right up.
Mine is an 02 C5, and have never had a battery drain even after sitting for a month or more. Have had a lot of personal issues this year so the most time that we were away was 4 days, and the other times just trips of 150 to 200 km round trip to go visiting, Just lucky I guess. And I don't have an Optima battery either. I'm not bragging about this just confounded cause I've heard about this issue so often.
Also Manny says when you put the battery on a maintainer do not have the battery still connected to the car. Makes sense when you think about it.
I have a 2008 and have never had any issues at all with battery drain, Never store in reverse, never take the battery out and honestly have never used a trickle charger during the winter storage either has always started not one concern
C-Tek Charging Facts

The first line in Battery Chargers And Equipment would explain why you should disconnect the battery before charging it. Charging facts It's strange that they warn about disconnecting the battery then include the adapter to plug into the lighter. The owners manual tells you to park in reverse with
the stick shift cars to avoid draining the battery and the DIC reminds people like me who keep forgetting. I've never had any problem with the battery draining. I left the C-Tek hooked up in the winter and the car never sits still long enough in the summer for the battery to go dead.
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No battery problems on my '04 C5, if it won't be used for a couple of days I use the Ctek plugged in to the ciggy lighter, takes all of 20 seconds.

With the red top / yellow top controversy on the "other forum" I have painted half the battery red, the other half yellow, compromise is always the Canadian answer. That would also explain why I have only one body side molding.

The only real "parasitic drain" I'm aware of would be the senate. YMMV
Tks again to all of you for your very interesting experiences with this issue. It seems it's a bit of a hit and miss issue on these cars as some of you have never experienced this problem. However I do have a C-TEK charger. Hopefully my C6 (when I buy it) will not be plagued by this problem.
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