Hey all,

2002 C5 Z06 here with about 95k miles.

Had the battery replaced around October 2019. I generally don't drive the car much, and during the last 2-3 months or so, have allowed the car to sit for 2-3 weeks, causing the battery to drain to the point that it wouldn't even start the car and needing a jump. Normally if I let it sit for under 2 weeks, it will still start no problem (slow crank, but it starts).

The second time this happened was March 23rd. Didn't drive the car for almost all of March. I jumped the car and drove it around for 30 minutes/10 miles or so. Today, I tried starting the car and not only did it not start, the battery seemed to be more dead than before and I was hearing a strange winding/grinding noise from the BCM/passenger footwell area.

I'm wondering what's going on here. Did my battery get so badly damaged from the two times it drained completely down? Do I have a good battery but have a parasitic drain issue? What's up with the winding/grinding noise I am hearing this time? I also tried locking the car via the Fob and noticed that when I pressed the lock button once, the car door's locking solenoid or whatever was clicking like 4-5 times. Guessing this is a weird C5 low battery quirk.

I live in an apartment and park in a shared garage with no electrical hookups, so a battery tender is out of the question.

Any help will be appreciated!


Thanks

 

First you need to get your battery fully charged somewhere and check if your current draw (drain) is normal (should be below 30 mA )
Shown in post #589 here

If you have excessive current draw a nice way to locate the circuit Fuse with too high drain current measuring mV over each individual fuse.

To avoid any further flat battery when you leave the car fore weeks you can instal a quick battery disconnector similar to

 

Remove the battery and fully charge it, then have it load-tested. Most auto parts stores offer free tests.

Deep discharging a battery can irreversibly damage it, or shorten its life. Repeated episodes are definitely not good...

 

I've been on the forum for almost 3 years now and I've read many, many posts about a dead battery in their a C5 .
It's obvious to me a person with a C5 needs to buy a battery maintainer and use it if they don't drive the car regularly.
Something about the electronics in a C5 will drain a new battery over a short period of time compared to other vehicles.
It's bit me one time and it really sucks when you hop in the C5 ready to go on a cruise and nothing happens when you turn the key!
Never again!
I had a couple of maintainers sitting around and after charging up the battery I fixed the maintainer up to where it only takes one minute to hook it up when I get out of the C5.
I know that some people aren't able to use a maintainer because of where they have to park the car. In that case they need to drive it more or get a jumper pack.
Good luck!

 

That's me. AND it helps me enjoy the car every week. I make plans looking at the weather what day in 7 I will drive for at least 30 minutes. Been doing this for 5 + years. No storage for this owner.

 

If you add a battery disconnect switch or just disconnect the battery you can prevent the car from draining the battery if it sits in the garage too long with no charger; there are solar chargers you can use if the car is parked in the sun for a few hours, just place the array on the dash and plug into the lighter socket.

 

Does it get sun at least for a few hours? If yes, and your car's sleep mode battery drain is within parameters (around 25mA), this should help.

 

Watch the cheap solar "maintainers". They have no regulation and will over-charge the battery killing it quickly.

In general, with a good battery you should be perfectly fine with it parked 2-3 weeks between drives. But, it needs a decent drive to get that battery fully charged again.

rrwirsi- I like the strategy. Don't maintainer it, drive it!

 

Thanks for the responses guys.

Well I ended up taking my battery to work where we have an on-site garage for our work vehicles and had one of the guys charge the battery up and load test it. The guy said it was still good during the load test but was a bit borderline.

Stuck it back into the car after getting home from work and it started up just fine. Car started up fine again today. Hopefully it's simply a case of me just not driving my car enough and for long enough in the few times I do drive it. Guess I'll be driving it more often!

 

Glad there were no complications after charging and load-testing the battery, but now you know you have to keep an eye on it to avoid another surprise (specially for the "bit borderline" behavior).

Hopefully everything will be fine by just enjoying your car more, but as it was asked before, does your car get sun at least for a few hours in your parking spot? If yes, and your car's sleep mode battery drain is within parameters (around 25mA), the Deltran Solar Battery Tenders could help with your battery health.

These battery tenders are fully automatic and won't overcharge your battery. They have 3 full models (panel with built-in controller) and a standalone controller, in case you already own a solar panel.

 

If its "borderline" and under a year old then bring it back and exchange it for a new one.

 

So I park in a shared and gated apartment garage and I have a 2-car tandem spot. The front of my spot (where I park the vette) gets a few hours of sunlight everyday, but I've recently been covering up the front of my vette with a car cover to protect it from the sun. I don't think I can rig it up to the fence since it will probably just get stolen.

Do certain batteries last longer than others? Sounds like my only recourse is to regularly disconnect the battery or just drive it more. I do make 1+ hour one-way drives about 3 times a month so maybe I can start doing that with the vette more.

Perhaps if my battery is doing bad soon and Costco tries to jerk me around, it might be an excuse to upgrade to a lightweight drycell battery lol