Hey guys.


I have a 2008 C6 coupe that's basically stock and about 72,000 miles on it.


I've been having a random battery issue for about the last 6 months. The issue showed itself when I started using it after the winter layover - the battery had been on maintenance charge over the winter. I went to use the car, but the battery was so dead that there wasn't enough charge to open the doors - I jump started it with no problems. A few days later I had the same issue so I replaced the battery with an Optima red thinking that the battery was at the end of its life. Problem solved? - no!


If I don't hook the battery to a maintenance charger (now of the CTEK variety), the battery will lose charge - sometimes in 8 hours, other times it will start after being laid up for a week or two. To be sure that it will start, I need to have it hooked up to the charger every time it's not being used.


The voltmeter shows about 14.0 to 14.3 volts when the engine is running.


I've pulled the On Star fuse, but that hasn't resolved it.


When it happened this morning, I hooked it up to the charger and there was a solenoid clicking in the right lower engine bay - I'm assuming that this is part of the emission control system, but it could be part of the issue.


Any thoughts or ideas of what's wrong or how to diagnose it?


Thanks

 

From your description of the problem, it appears that you have something drawing far more current than there should be in the electrical system when the car is off. If you have an ammeter, connect it in series with the battery (positive cable) with the engine off to see what current is actually being pulled through the system. More current than just enough to keep the electronics for the doors/theft system active would indicate you have a problem. The current draw in this manner should not be over one amp or so. I have a Red Top in my other car and really like it. It should provide several days of current to your car in the engine "off" position and still start the car, given no problems with your electrical system. Lastly, you could disconnect the alternator and then measure current draw at the battery in the manner I previously mentioned (engine off). Your alternator could have a bad or leaking diode which would also be a source of a current draw

Also, I don't know if this is any help, but the solenoid in my 2007 was replaced under a recall.

Steve

 

Something isn't shutting down. You will need to do a draw test to find out how much and start disconnecting modules to find the culprit.

The draw after full shutdown should be no more that about .015A - .030A. Take a look at post 77 in here for a "typical" draw test result:

https://www.corvetteforum.com/forums...yndrome-4.html

 

I haven't had the problem but have done a draw test just to know where I stand...mine has no Onstar so it draws a bit less, 11-17 ma after giving everything a few minutes to calm down.

 

Other things to consider:
When the Battery is dead , confirm the battery voltage.. AT THE BATTERY. If the battery is in fact dead, this will eliminate ALOT of checking other things.

Until you fix the drain issue, get a battery disconnect.. I have em on ALL my cars...

I modify mine to put 2 small screws on either side of the disconnect to make it easy to hook an amp meter up to solve issues.

Inspect the starter solenoid input stud... over time these get AFU due to heat & corrosion.

Mike

 

Some new events to report:
- I put a battery disconnect switch on the negative terminal.
- I disconnected the battery, then tested the current being drawn. To my surprise, I nearly melted the wires on my 10A meter - the meter read off-scale high (more than 10a). I didn't have anything turned on in the car.

It scared me - I disconnected the battery, then closed the garage door.

With that kind of power being used, I'm guessing that it's not something electronic - more likely something like a seat heater or bad diode in the alternator.

Probably time to take it to my local stealership.

 

I've got the same sort of problem. It started after I pulled the radio bezel. The radio bezel is still out, since I'm doing some upgrades. I can hear an intermittent clicking from right side, every 10 seconds or so. Like the op, my battery goes dead overnight. I have a tender on it now and I'll look into it more when I get the bezel back on. I don't believe much in coincidences, so I hoping it has something to do with the bezel and associated wire plugs removed.

 

I am surprised your test with the ammeter showed that much of a current draw. Before you hit up your dealership for the repairs, check the alternator - - it may be warm even with a cold engine. If so, you've got a leaking diode. Better yet, disconnect the battery, then disconnect the output lead or "A" lead from the alternator, then do the current draw test again. I've also heard that the seat adjustment motor(s) can stay engaged even when they're not moving the seats. That (and/or a bad window lift motor) could pull 10A or more.

Steve

 

Very interesting stuff above.

 

Does it have an aftermarket radio?

 

https://www.corvetteforum.com/forums...d-stumped.html
It has a PDF that shows how to hook up a multimeter to get the current draw.

 

Hook up you meter with the draw showing. Then start pulling fuses until the draw goes away. Start with common items first. Seats, windows, cluster, radio, etc. you will see the amp draw drop to almost zero. I do this for a living at a dealership, and that is exactly what we would do. If you have an intermittent draw hook up a good fluke meter with a min/max function or a scope with timer. You can catch exactly what time the draw starts and how long it lasts.

 

No, it's a stock radio/cd/nav unit.

 

Oh well, that eliminates that as issue. The shop I use has had several instances of aftermarket sound system installs that have caused battery drain.

 

Over 10A !!! wow... something is really not right....
I agree, start with pulling the BIG LUG on the back of the ALT.
OH also be aware of the Delayed Accessories Bus...
AND
If you are in a state the car THINKS it's dark outside.. it will leave the lights on as you exit... So you have to make sure all that sillyness is not happening...

 

Check the wires going to the starter also.

 

LATEST: Tested the battery draw using the method in the above link and I got the following:
Time 0 - 3.5amps
1 min - 3a
1.5 min - 0.21a
3 min - 3a
3.5 min - 0.07a (constant until I stopped the test after 15 mins)
(Times are approximate)
I ran the test two times and got the same result.
I'm no expert, but 0.07a is a pretty low draw and probably isn't enough to drain the battery in 8 hours.
The battery tested 12.6v then 14.6v with the engine running.

Any ideas?

 

It's been a long day, so I'm a little fuzzy. So your test showed a 3 to 3.5 amp draw intermittently? If so, that would be a problem. Have you done any troubleshooting to find out where the draw is coming from?

 

If the door was opened, it will leave stuff on for x amount of minutes and that could be the reason the drain goes away.

 

The doors were closed throughout the tests. Nothing was opened or closed or switched on during the tests too.


I looked through previous posts, and my results appear to be in line with their 'normal' results (although my final reading of 0.07a appears to be higher than theirs [0.036 and 0.007a], but is real low). See https://www.corvetteforum.com/forums...ead-again.html post #14.


I'm guessing that the battery drain is an intermittent fault - something is randomly waking when everything else is turned off. I probably need to run the test with a scope with a timer as Medicdiver suggested.