I have a 2009 Chevy Aveo which has had an ongoing problem for months. Every night the battery completely dies. The first thing I did was replace the battery with a brand new one (and, later, replaced that one too - hey, you can never be too careful) but it kept happening. Two mechanics have told me that the alternator seems to be working fine and is definitely charging the car while it runs, and that there’s got to be a draw on the battery when the car is off.
But here’s the weird part. When they test the battery for a load with a voltimeter/ampmeter/whatever, there’s no unusual draw at all. Obviously there has to be a draw sometime, because the thing is at 12.6V when I go to sleep and 4.0V in the morning. I know this because I had to buy a big stand-up battery charger that I use every day.
The conclusion the mechanics have come to is that something is “turning on” after the car has been off for some time, and draining a lot of power. How can I find this? What could it be? Help me, Car Talk Community, you’re my only hope!
Does this car have a remote starter system (either a “factory” system or an aftermarket system) installed?
I have seen instances where malfunctioning remote start systems did some very weird things when the car was sitting idle, and these strange electrical events could be draining the OP’s battery.
If there is a remote start system, I would suggest that the OP have it disconnected.
Ah, I should have mentioned that, because the mechanics asked me, too. No, this is a completely stock 2009 Chevy Aveo with no aftermarket mods except a block heater (I live in North Dakota).
Did you buy this as a new car, or did you buy it as a used car?
I ask because buyers of used cars are sometimes not fully aware of the equipment on their car.
Until the problem is tracked down it will be less stressful on the battery if you disconnect the negative terminal each night.
There could be a problem with the EVAP system, which runs after the car is off a few hours.
“There could be a problem with the EVAP system, which runs after the car is off a few hours.”
+1
Yes, that is another possibility.
The EVAP system should run for only a couple of minutes when the car is idle, but if it is malfunctioning, it is very possible that it could be running long enough to drain the battery.
I’m wondering if you have any specifics on “no unusual draw at all.” Do you know what level of draw was actually observed?
Personally, I guess I’d be thinking about a “stakeout” - hook up a meter at the end of the day, leave it on, and keep babysitting it until something happened. This isn’t really practical for a shop to do. I’m sure some clever work with a webcam or something and you could babysit the meter from your couch.
I ask because buyers of used cars are sometimes not fully aware of the equipment on their car.
That’s a good point. I only assume I don’t have one because the seller never mentioned it, there’s no fob on the keys it came with, and it’s the base model of the Aveo. And the mechanics I took it to didn’t say anything abuot a remote starter. Is it possible I have one tucked away, maybe?
Until the problem is tracked down it will be less stressful on the battery if you disconnect the negative terminal each night.
My coworker suggested buying a knife terminal switch and just using that, since I’ve been wrestling with this problem for so long. My understanding is that does the same thing a little easier. Am I right?
There could be a problem with the EVAP system, which runs after the car is off a few hours.
This sounds very promising! How would I find out it’s the EVAP and not some other random thing, like the rear defroster (also suggested as a possible random switch-on by mechanic)?
I'm wondering if you have any specifics on "no unusual draw at all." Do you know what level of draw was actually observed?
They didn’t give me any numbers, but of the two mechanics who specifically checked the load, they both said the car should be fine for “months” without losing charge. I’m not sure how many milliamps that implies.
Thanks a lot for your help thus far, guys! I think I am going to try that webcam stakeout thing. I just hope my laptop doesn’t freeze solid in this godawful ND winter.
There could be a module/computer that fails to go to sleep after the vehicle is shut off. Or a module/computer that wakes backup after the vehicle is shut off. These are called F.R.E.D.'s
You can’t use the old method to check for a parasitic current draw because disconnecting the battery forces the offending component to go to sleep. So when you go to check for the parasitic current draw it’s not there.
You have to sneak up the current draw to catch it. Here’s how that’s done.
I had a fan controller do this on my car and didn’t figure it out until I was walking by the car 3 hours after it had been shut off and heard the radiator fans start up.
I have to wonder if the shop checked to see if the trouble is being caused by the alternator backfeeding current due to a bad blocking diode inside the alternator. They may have overlooked that in their testing.
I agree with @db4690 that normal current draw should be less than 50 milliamps. More like 25 would be prefered. Aftermarket accessories can make the reading go higher if there are some installed on the vehicle.
It sounds like something is happening during that night that draws a lot of current. Presumably the tech is observing nothing beyond 50 ma of parasitic drain initially. The comes back in the morning and finds the battery drained. A car battery has a capacity of about 30 Amp-Hours, which means it would take 30,000/50 = 600 hours or 25 days to drain the battery at a 50 mA rate. So something big must be happening at some point during the night.
hmmm … electronics types with access to professional equipment would put a instrument on the battery lead to monitor and log the current drain vs time. Then you’d know how many hours it took before whatever is happening, happens. While the typical shop wouldn’t have this kind of equipment, I think a mechanic who specialized in auto-electrical diagnosis would at least have an instrument that would measure the peak current flow occurring during the night. That would provide a big clue as to what is happening.
It has to be something turning on that produces a lot of current drain, like the starter motor engaging, the headlights coming on, or the alternator shorting out. I think you just need to phone around to find an auto-electric shop that has the proper equipment to log the parasitic current vs time is all. Then you’ll know when it happens, and can be there the next night to see what exactly is going on.
I guess if I had this problem myself I might see if I rig a way, using a relay or a thermostat or something, to turn a loud radio on when the current drain exceeds 1 amp.
BTW, this situation could well present a fire hazard. OP may want to avoid parking in a garage until it is resolved.
Um, if the battery is regularly dropping down to 4 volts, if it wasn’t bad before, it is now. Nor do I see any mention that the battery was load tested.
"Nor do I see any mention that the battery was load tested. "
This was in the original post:
"The first thing I did was replace the battery with a brand new one (and, later, replaced that one too - hey, you can never be too careful) but it kept happening. "
I guess all three batteries could have been bad including the two new ones. Implausible. Though you’re right that each one, including the one in there now has been abused.
I know this post is a little old, but I’ve been having the same issue with my 2009 Aveo for about 2 years now, and I bought it brand new, base model as well.
Chevy wouldn’t acknowledge any problem once I replaced the first dead battery with a non-chevy brand battery, and I’ve not had the money nor energy to put into figuring out what’s the issue. So I go and get my still under warranty, only a couple weeks (or sometimes days) old battery replaced all the time. I’ve probably replaced it 18 times in the last two years.
I’m not as auto aware as some might be, but the issue sounds the same… battery dies, its not the alternator, and nothing appears to be putting a drain on the battery, although something clearly is.
Sometimes the replacement battery will last a few months before dying over night, other times it will only go about a week before I have to replace it again. It will always jump, but drains progressively more quickly the longer I wait to replace it. Sometimes its less than 4 hours before its drained again, other times it takes over 12. I’ve seen a ton of forums on the issue for the 09 aveo, but never have seen one where someone has figured it out.
kind of just waiting for the factory recall at this point, but would love to hear if you’ve gotten any further in this.
