Recurring Power Drain

[Patrick]

I've now had to deal with the same problem three times in the 14 months since I got my '06 Convertible. The problem is some form of power drain that kills the battery.

When this first came up a year ago in October, I attributed it to the fact that prior to my purchase of what had been a dealer demo, the car had sat on the dealer lot for several months, being driven only infrequently. I replaced the battery, and problem seemed to go away. For a while.

It began to re-occur at the beginning of this year. Again, I attributed it to the fact that over the winter, the car would sit in my garage not being driven for weeks at a time because of road conditions. (Even when it isn't snow and ice covered, I hate driving the Vette while there's still lots of sand and gravel on the road.) Even when I recharged it, however, the battery would still die within a few days.

So I took it in to see if there were some form of short. The dealer couldn't find one, but did find there was a malfunctioning module which he replaced. Again, a new battery was installed (this was in March).

The car has worked fine through the spring and summer. It never sat in the garage for more than two or three days at a time, and it always started up just fine. I drove it this past Sunday, down to Colorado Springs and back and saw no signs of any electrical issues. Wednesday morning, only two days later, I went to start the car, and I got that familiar click with no turn-over of the engine.

So, charging it up again, I brought it back to the dealer. The dealer called me today and said the problem was dead battery cells. After two days, I asked? Yes, he said, and indicated to me that this was not unusual: he said there are 18 or 19 separate computer modules that "wake up" even when the car is not on, and run diagnostic checks, and those checks cumulatively drain the battery. His advice was to always connect the car to a trickle charger, even if I'm planning to leave it parked, in my garage, for as little as two days.

He went on to claim that this is, apparently, not an unusual problem. That he sees it all the time on Corvettes, the newer Suburbans and Tahoes, and on the Avalanche. All of these cars have these independent modules which perform self-diagnostics even when the car isn't on. He even told me he sees it frequently happen when people drive their car to the airport, take a three or four day trip, and return only to find their battery has died.

I made no argument with this guy, because frankly I've lost confidence in what he's telling me. If this Service Writer's story was correct, wouldn't there be a mention of this in the owner's manual? It seems to me that three battery changes in a year is excessive, and points to a larger problem of some sort. And why would GM design a system that requires you to connect a trickle charger to it if you're going to leave it parked for as little as two days?

My plan is to take the car, and the paperwork this guy gives me, and visit another dealer to see I get a different answer. But I'd like to know if anyone else is experiencing these kinds of power drains on their C6s.

 

[c4c5specialist]

OMG< glad your going to another dealership.
Maybe THEY can give you the straight scoop.
Fact is, 10-20 milliamp draw is normal. With that draw, your battery can last 1 month minimum without usage.
Now, there is obviously MORE than that creating your condition.
You will have to check on the programming of the PCM, RCDLR and BCM.
Your powertrain control module(PCM) is the first one to check as there is a docu mentfor this condition.
Your remote control door lock receiver is the NEXT one, which also has a TSB
I like to personally check the BCM only because this is the power mode master and communicate with EVERY module.
But you can also tell them about the document about power draws specifically for Corvette.
They can print it and show you.
Allthebest, c4c5

 

[twiget]

My dealer told me the same thing, about the car "waking up" and running various diagnostics even when she's just sitting there. They told me that putting the tranny in reverse (for 6-speed's anyway) when the car is turned off would disable these automatic diagnostics. I have never left mine in reverse, but then the longest she ever sits, is over night.

Good luck, Patrick.

Jason

 

[midyearroadster427]

invest in a good charger like the battery tender or the ctek saves a lot of hassles

 

[minifridge1138]

I think your dealer is full of it.

If these cars drained a battery in 2 days, then every car that was shipped from the assembly plant would arrive with a dead battery and so would every car on the lot that wasn't test driven every day.

I see 3 options for you:
1) ignore the problem. Trickle charge your battery everyday. (Fire hazard).
2) ignore the problem. Disconnect the battery everyday. (who needs radio presets).
3) Find and fix the problem. (try another dealer).


Good Luck!

 

[Patrick]

invest in a good charger like the battery tender or the ctek saves a lot of hassles

That's actually the advice I got from the dealer I went to this week- the same dealer who's now replaced my battery three times in the past year.

I keep coming back to the fact that the owner's manual makes no mention of the need to use a trickle charger if the car is going to be parked in the garage for as short as two days. That can't be normal.

 

[Patrick]

I see 3 options for you:
1) ignore the problem. Trickle charge your battery everyday. (Fire hazard).
2) ignore the problem. Disconnect the battery everyday. (who needs radio presets).
3) Find and fix the problem. (try another dealer).


Good Luck!

Thanks, Minifridge. I'm taking option 3: I've set an appointment with another dealer for next week. I've carefully explained to the service writer I talked with how frequently the car was driven in the week before the battery went dead, and mentioned the TSB's C4C5Specialist mentioned. We'll see what happens.

 

[Tuna]

Both my C6's sit for days at a time in the garage without killing the battery. The longest either as sat has been 2 weeks without any problem with a dead battery.

Of course we always put the cars in Park (auto) and Reverse (man) when parked and the key fobs are stored inside the house several feet from them (I don't want the fobs too close or it might keep 'waking up' the cars and draining the battery.

Definitely try a different dealer.

 

[Patrick]

Of course we always put the cars in Park (auto) and Reverse (man) when parked and the key fobs are stored inside the house several feet from them (I don't want the fobs too close or it might keep 'waking up' the cars and draining the battery.

I have a manual transmission, and I'll plead guilty to the charge of not always leaving it in reverse when I park it. I remember to do that about 50% of the time, so that could be a contributing factor here.

My garage is detached from my Townhome, and separated by about 25 feet. So I don't think that's a factor here.

 

[Scottsredvette]

Hey Patrick,

Change dealers. How much longer is your warranty good for? Or, call Rik. He might have some ideas.

Scott

 

[Patrick]

Hey Patrick,

Change dealers. How much longer is your warranty good for? Or, call Rik. He might have some ideas.

Scott

Scott,
Based on when I got it, the car is under warrantee until August, 2010. I agree that calling Rik is a good idea, but as it's still under warrantee, I'd like to exhaust my remedies with GM first.

-Patrick

 

[Patrick]

Update:
I've now been to a different dealership. And I'd like to thank Paul for giving me some helpful things to point them toward:

You will have to check on the programming of the PCM, RCDLR and BCM.
Your powertrain control module(PCM) is the first one to check as there is a docu mentfor this condition.
Your remote control door lock receiver is the NEXT one, which also has a TSB
I like to personally check the BCM only because this is the power mode master and communicate with EVERY module.
But you can also tell them about the document about power draws specifically for Corvette.
They can print it and show you.
Allthebest, c4c5

This second dealership discovered that the RCDLR had not been reprogrammed per the TSB Paul wrote about. The result, according to the Service Writer, was that even after I shut the engine off, got out, and the car armed the alarm, was that the car was still in 'run' mode. His technician figured that out as soon as he moved the car into the service bay.

From the paperwork they gave me after the reprogramming of the RCDLR, and the power draw test:

Battery tests good at 689 CCA, and draw at 17mA, Alternator charging 14.6V.

Let's hope that's the end of it.

 

[Tuna]

Great news.

 

[NORTY]

As infrequently as some owners drive their Corvettes, this has been a problem (current draw when static.) I doubt this happens with Cobalt owners as they drive their cars all year. Maybe GM could install a "sleep" mode that disconnects the neg cable or something for extended non operation. A healthy battery loses 1% of charge everyday. A battery that has been deep cycled isn't a healthy battery, (unless designed for that purpose.) Automotive batteries are not "deep cycle" units. The Corvette does "wake up" when it isn't necessary. I don't know if the FOBS makes a difference regarding distance from the car when in non op. (I've heard it does.)

1. Get a battery tender.
2. DRIVE your car!
3.

 

[Patrick]

As infrequently as some owners drive their Corvettes, this has been a problem (current draw when static.) I doubt this happens with Cobalt owners as they drive their cars all year. Maybe GM could install a "sleep" mode that disconnects the neg cable or something for extended non operation. A healthy battery loses 1% of charge everyday. A battery that has been deep cycled isn't a healthy battery, (unless designed for that purpose.) Automotive batteries are not "deep cycle" units. The Corvette does "wake up" when it isn't necessary. I don't know if the FOBS makes a difference regarding distance from the car when in non op. (I've heard it does.)

1. Get a battery tender.
2. DRIVE your car!
3.

Here's an interesting question to ponder: besides Corvette owners, how many others in the motoring public know about, let alone have in their garage, items like some sort of trickle charger or Stabil for the gas tank?

 

[twiget]

Here's an interesting question to ponder: besides Corvette owners, how many others in the motoring public know about, let alone have in their garage, items like some sort of trickle charger or Stabil for the gas tank?

I'd venture to guess that most anyone in the car hobby, who puts their toy's away during the winter knows about those products. Heck, my Mom, who is about as technologically challenged as one can be knows about a trickle charger.

Jason

 

[c4c5specialist]

Hi there,
A little more specifics should be understood.
#1, CAN networking the computer modules within C6 enables the SLEEP mode.
#2, only when a module is awoken or commanded to come to life, does the battery draw increase.
#3, this is the reasons for the programming changes, because some modules were coming awake WHEN they were NOT being commanded to.
#4, within 10 mins, all modules are asleep, unless there is an aftermarket load on the system or something is left on.
#5, with the 10-20milliamp draw, that accounts for the radio memory and clock, as well as ONSTAR.
So, that being said, the communications system over C5 is completely different and should be understood.
Allthebest, c4c5

 

[Scottsredvette]

Here's an interesting question to ponder: besides Corvette owners, how many others in the motoring public know about, let alone have in their garage, items like some sort of trickle charger or Stabil for the gas tank?

Been using battery tenders for years on my tractors ($6.00 at Harbor Freight).
Been using fuel stabilizer in my rec truck for a few years.
And, if the roads are clear, I drive the Vette in the winter. It doesn't get put up.

Scott

 

[Patrick]

I'd venture to guess that most anyone in the car hobby, who puts their toy's away during the winter knows about those products. Heck, my Mom, who is about as technologically challenged as one can be knows about a trickle charger.

Jason

Been using battery tenders for years on my tractors ($6.00 at Harbor Freight).
Been using fuel stabilizer in my rec truck for a few years.
And, if the roads are clear, I drive the Vette in the winter. It doesn't get put up.

Scott

Well then I must be in the distinct minority. I asked my co-workers. Apart from two or three who make a hobby of restoring vehicles, the vast majority I asked thought "trickle charger" was something you hooked up to your sprinkler system and irrigated your garden with. And "Stabil" was a roadside DUI test performed by the police.

Go figure.

 

[LC2001]

If you pay 50G plus for a car and the battery is dead in two weeks or less I think GM should fix the problem not say hook up a charger. If it needs pluged in all the time put the charger with a plug installed at the factory and a disconect when the wife goes to the store and dosen't unplug it. A car should start after a month of setting.