Hello fellow Corvette enthusiasts. I have been having a serious battery drain problem with my 07 Z51. A little background: The car was in storage since last August while I was in training (Army). The battery was on a tender until I returned this past May. Battery went back in, car came out and all was good. One month later I PCS'd from Ft. Bragg, NC to Ft. Lewis,WA with the car on a U-Haul trailer (long drive). I started noticing a battery drain issue right before we left. I would have to start the car every couple of days, and then at least once a day. Pretty soon that didn't even work. After jump starting her a handful of times I said "F it" and waited until I arrived at Ft. Lewis to start her again. Arrived at Ft. Lewis, jumped her and took her to get her battery charged and the alternator tested. Took it to two different places, used different testing equipment and both said the battery and alternator were good. With a charged battery I locked the car, tripped the passenger door locking mechanism and put my key fob inside the house. After waiting 15 minutes I disconnected the neg battery cable and hooked up a test light in series back to the battery. I disconnected the alternator and no luck. I then systematically pulled every fuse and rely in the floorboard and in the engine bay fuse box. The light never went out. I then disconnected the wire at the jump bolt adjacent to the engine bay fuse box. Bingo! The light went out. I reconnected that wire and disconnected the two main cables to the starter and the light did NOT go out. So gentlemen, there is my riddle. Any and all suggestions would be greatly appreciated because this is becoming a huge PIA.

 

Did you happen to measure the current draw after everything was supposed to be shut down? There is a slight possibility that could help identify where the problem is, but can't guaranty it.

 

FWIW: "Battery tests" are seemingly worthless. I would NOT under any circumstances have any faith that just because a battery "tests good" that it actually *is* good. I say this from personal experience and from the experiences of others.

"Battery tested good" ... LOTS of threads here that have this phrase in them end with "replaced battery and now all is well".

You may well have some other issue, but I wouldn't make assumptions on battery condition based on the "test".

 

if you have heated seats, the relay has been know to stick.

 

Power wire from starter to fuse box may be chaffed and shorting to ground. The chafing process can build up a layer of oxide at the short causing resistance and the wire not burning. Follow wire and check for damage.

 

Not yet. Good idea.

 

Check your driver side power seat switch, that was my problem causing drain. The switch was sticking from day one.

 

How old is the battery? Full discharges kill batteries. And those testers have passed batteries that were junk in my experience. If it was my car, I'd buy a new battery. When I had a similar problem, that's exactly what I did as a matter of fact.

 

Do you have OnStar that isn't activated? It is a known battery drain.

 

A test light like that will not even register the 11-17 ma that my car draws when all quiets down. You really need to get a decent meter that can register up to 10 amps of current and put that in series, give it 5 minutes or so for the computers to go to sleep, then measure the draw and start checking things.

And I agree about Onstar....first place to check.

 

Small correction: A *malfunctioning* OnStar can be a battery drain. OnStar units that are operating properly don't present a current drain issue, activated or not.

 

Thanks for all the replies. Work has been crazy but I plan to try everyone's suggestions tomorrow. I'll update then.

 

Battery tests are not worthless, some battery testers are.

 

Amen to that, the Carbon Pile load tester is the gold standard for battery testing. Impedance testers (which are in vogue now) are notoriusly unreliable.
I would hesitate to buy a new battery or junk a current one based on anything but a Carbon Pile load test on a properly charged battery.

 

I had issues with my 08 last year. the Delco battery was 2 years old and had been on a battery tender since new when stored. When the battery failed initially I had the battery tested battery tested multiple times at Autozone, AAA, and the dealer again and all reported the battery and alternator were functioning properly. After week of total frustration I decided to purchase a $2 battery hydrometer, fully charged the battery and tested each cell. Hydrometer reported 2 dead cells, replaced battery and no more issues since April 2014. My opinion is that the best battery testing device is a $2 hydrometer from Walmart :-)

 

Another way to definitively test is to fully charge the battery, pull it off the charger and let it sit 24 hours (no xternal connections). With two dead shorted cells, you'll find the battery voltage at less than 10 volts.

 

Update. So today I bought a Bosch FIX 7665 multimeter and proceeded to try everyone's suggestions. First attempted to trace the jump bolt wire from the engine bay fuse box to see if there was a bare spot grounding it out, it was all good. Onstar is not activated so I moved on. Tested the battery and it was low, 12.26v, but I continued with my tests. Disconnected the drivers power seat (I don't have heated seats) and still had a battery draw of 2.00 which dropped to .47 amps. Disconnected the jump bolt cable and the draw disappeared. I pulled the battery and plan to charge it overnight. To everyone who suspects I have a bad battery, and I may, what could be causing that much of a draw?

 

I'd suspect your battery needs to be replaced if it's the original one from 2007. I've replaced batteries for friends with '07 and '08 Corvettes and each car was on a battery tender. No clue what might be causing the draw down you measured.
P.S. Thank you for your service.

 

Even with Onstar not activated, the link still exists and they can track you unless you call and request the two way link be severed. Onstar intermittently powers up and pings your location. This would cause an intermittent spike in current draw.
Just a heads up.

 

Your battery is good if it had not been charged in 24 hours, or the car not driven in 24 hours.

With Onstar out of service, it has caused battery drain with some of the forum members. There are threads documenting this.