sd455ta

Has anyone measured or read somewhere exactly how many "milliamps"
of current the Corvette alarm system & other computers use, when the car is at rest, all systems off & locked up?

You need to know that number, before you can determine how many days that a fully charged battery, that is performing to its specifications, will last. You should be able to tell what the voltage will be after any given week of no use.

You should be able to know what the minimum battery voltage is to start an LS2 engine at any given temperature, with factory oil viscosity, & some many miles of engine wear. These numbers are available somewhere.

I do not think there is anything such as DBS.

What you do have is:

1. A battery that is defective, but you do not know it

2. Something within the car's electronics, is causing a far greater than normal current drain when shut down.

3. Or both of the above

4. There is a remote chance that the cars charging system, as a whole, is not maintaining the battery up to rated voltage after start.

With an 80 amp alternater system properly working, you would be hard pressed to use up all of that ampere, simply by having all of the electronic devices in you car at the same time, under normal use.

You would have to have all headlights, fog lights, wipers, defrosters, heated seats, brake lites, fan on high, radio interior lights, HUD hood open, doors open, hatch open, everything that use electric power on AT ONCE, to exceed that 80 amp capability of the charging system & therefore start to drain down your battery capability!

Regards, Rich

MSME, BSEE

PappyTinker

Thanks for that posting. Thoughts similar to that have been running around in my mind for a long time but I do not have the expertise to make the points you have made. No vehicle should have the battery run down as fast as some here on the forum have indicated unless the operator has left lights or something else on (failure to follow shutdown procedure?), the battery was manufactured by total incompetents or there is something wrong with the electrical system in the vehicle.

PJinNJ

BUT I don't understand the value of stating the obvious and all of the things we already know. We know all of these thing yet we have not discovered the reason/cause/defect/problem.

6spdC6

You would think much different about DBS if you had a car that had the problem.

Your point 1 Have had DBS twice, car has gone back to dealer twice, battery has been checked out twice, (ok) In fact the same battery is in car now (tender on for winter storage, will come out of hibernation in a couple weeks).

Your point 2. I tend to agree with that one. Either something does not shut down as it should, or something OCCASIONALY wakes the car up after it is shut down. DBS (05 6spd) is a event that occurs after the car is shut down in the way GM says to do it. Some people say "O you must not have put it in Reverse" In my case that is impossible as I always drive in garage, shift to reverse and back up a couple of feet, then shut down as recquired. + all sorts of horns blow if you are not in reverse.

Yes Virginnia there is DBS. By taking out the reverse/stearing interface in 06 models, DBS is a non issue. Most of us feel that this system is the problem. GM is looking into this at last, but not moving fast enought to find the cure. a lot of people have said to get a pirority start, that does help. It is not a fix, but a bandaid on the problem.

lytmup

I dont know what the resting draw of the Vette is, but check this out:

I had a 00 Camaro SS in which I replaced the factory head unit with an aftermarket head. The aftermarket head unit needed a "constant" power supply to retain its memory settings, and so I hooked it up to the factory wiring constant lead.

After 2 solid days of sitting (no starts at all), the battery would go completely dead. I put an ampmeter in series on the battery to find that the aftermarket head was drawing 2 milliamps of juice. Not many people believe that only 2 milliamps could draw a battery down in only 2 days, but I tested it time and time again.

I rehooked the factory head unit and the draw went down to .001 or something. It appears that the factory head maintained a capacitor for its memory settings and must have only used the constant power lead if the capacitor got low.

So, my long point is, believe it or not, is that 2 milliamps of draw can suck a battery down within 2-3 days.

As for DBS, I dont know what is causing it. But, what does stand out is that no one seems to be having the issue on the 2006 Corvettes with the "Park in Reverse" feature removed. I am of the camp that believed the problem was in that circuit (possibly a unintended short or bad ground)

NORTY

I suppose the only "slam dunk" fix would be to install a battery isolation switch when the car is latent.

ronsc1985

I think you missed something in your measurements. A 2ma current draw would require 500 hours to use 1 amp hour of battery reserve. Since your battery has 25 or more amp hours of reserve the 2ma is not the cause. What were you using for a battery, 8 D cells in series? Even with that you could make 2 or three days at 2ma.

torquetube

Abnormal, excessive draw is the suspected cause of what appears to be a rash of dead batteries on '05 MN6s, a.k.a. DBS.

lytmup

Like I said, most people dont believe me. I also realize what logic would dictate should happen to the battery given that kind of draw, but it happened just the way that I said. Hell, I didnt even believe it myself until I tested it over and over again.

I can only tell you what I measured and what happened. I missed NOTHING in my measurements. I even showed the mechanics that were trying to figure it out at the time that wouldn't believe me either just to prove my point.

timd38

The part you don't know is what module in the CAN BUS turned itself on and drained the battery. That is really the question.

Hoonose

Someone did this a year back, and I believe the battery should last weeks if left on its own.

#2 is the basic cause of DBS, and it's real.
#1 would just let DBS happen in fewer hours.

I've had 3 or 4 episodes of DBS, and at also least 2 other explainable dead batteries since Oct '04. I never replaced the original battery and the car has had no dead battery episodes in a year now.

DBS specifically happens over the first 24-48 hrs of the car being left alone. That's a clue that something major is not turning off.(or coming back on)

My theory of DBS is a defective (or slow to engage) reverse sensor switch. So far it explains everything, but of course is not proven.

Hoonose

The prioritystart module makes more sense though, since it works only if really needed. Total isolation, and what would happen to onboard computers and timers, etc. on a daily basis?

double eagle

Had a similar 'DBS' on my '04 BMW 330Ci after a couple of months ownership - problem was diagnosed in a few weeks - BMW determined the '04s climate control was drawing 800ma at rest instead of 8ma killing the battery in a few days of non-use - software update cured the problem. Hopefully GM will find a solution soon.

Hoonose

There have been similar theories with the C6 over the past year that never panned out. Removing relay #46, and also a potential problem with a headlight module.
The only problem, is those answers never explained why there were mostly MN6 dead batteries. And people also had dead batteries again after relay #46 removal.
The answer probably remains somewhere in the reverse/steering lock area that has been removed for '06.

mforman42

The 'sleeping' current draw is only a few mA. It will depend on what options you have installed. The likely cause of DBS, as others have stated, is a defective part drawing larger current.

There is the possibility that there is more than one 'root' cause of the problem. It can be caused by any one of many modules either failing to go into sleep mode or waking up after initially going to sleep. It may also be that the car is 'awakened' by some external influence that is similar enough to a key fob that the car thinks it recognizes a fob in the area.

In the case of my other car (a Jag XJR) there was a control module intermittently not going to sleep that caused a dead battery while on the showroom floor. It took two days to isolate the module. If your dealer is willing to invest the time, they can find the problem for your particular car.

xs650

Something doesn't fit. Normal power off battery draw on a modern car is lot higher than 2 mA. 2mA wasn't draining your battery enough to cause a problem.

Parasitic loads of up to 50mA are normal on a car, some are bit higher, some are lot lower.

Hoonose

They will/have not in well over a year!

mforman42

While I can sympathize with you, it is *possible* to find the glitch, just very time consuming. Of course, it may be a better use of their time to just replace the car under whatever lemon law Arizona has. If you haven't gotten the problem solved in a year, and GM hasn't stepped forward, it is time to contact an attorney.

My sister had an Impala with similar issues, and GM didn't respond until an attorney got involved. Then she suddenly had a full refund on the car, even though the period for the lemon law had passed.

Just my $.02 worth.

Hoonose

I didn't mean to imply that they have been working all year on my car.
I feel that my problem is solved since I have not had another episode in a year.
I meant that others on this forum have had their car checked and monitored and reported over this past year, either through their own resources or dealers and most have arrived at no useful conclusions. I say most. In a few they did find a glitch somewhere. One was the #46 relay, another a headlight module, and another was with Trayc6, but I forget the long term or end results of those last two. The #46 relay hasn't panned out long term.
I have heard of at least a few bad cases of recurring DBS that I'd bet a lemon law would apply.

Norske

Today I took my 2006 (MN6 NAV OnStar) to the dealer to check for a bad battery. The tech measured the quiescent current draw at 44mA and mentioned that anything under 50mA is expected and acceptable. He let the car sit for about 30 minutes to be sure all systems had shut down, and the current never went above 44mA.

I had the car in because its battery voltage falls to about 12.1 volts within a few hours after shutting down, no matter how long I've run it. I thought that it should be staying up near 12.5v or so.

The tech mentioned that the LS2 motor should start even with a battery voltage as low as 9.8v as long as it's able to supply the necessary current. My battery was putting out 545CCA during the load test, which is plenty, so the GM definition of a bad battery was not meant and they could not replace it.

Of course, the battery voltage after all that testing was still at 12.56 volts! It had started out that morning at 12.0 volts, then was driven for less than 15 minutes to get to the dealership.

Tonight, the demon battery is back down to 12.1 volts. But to its credit, it hasn't actually failed to start the car yet, even after sitting for 10 days. It's waiting for me to travel far away from home before it strikes, I'm sure.