TexasHiwayman

I was under the hood and noticed Neg batt cable was slightly loose. I tightened it.

2 days later, the "service charging system" warning came up. Voltage would start at @8.5, then go up to 14.2-4. Warning cleared.
Then the car started not starting. The deadly loud click and nothing else. Cables were tight, voltage appeared to be low. Put meter on it and it was @11. Cycling between "ACC" "OFF", and "ON" seem to start car. I was driving the car home when the "service charging system" warning came on. 10 minutes later the voltage started dropping rapidly. "Low battery voltage" warning came on. Systems started shutting down, active handling, traction control, etc, as they should. Got off the highway and was headed towards a parking lot. Then the instrument panel died. Went into parking lot on 2-3 cylinders firing (it seemed). (Strange thing is that I was monitoring the batt voltage on "Gauges". I watched it slowly drop through the 14s into the 13s. No lights on, radio, etc. Car had driven 20-25 miles at this point. It suddenly dropped from @12.2 to 9.8 It went about 4-5 more till it quit.
Had the car towed to my house. Tried to charge the battery but it wouldn't hold a charge. It kept faulting the charger out. Bought a new battery. It started the car. Ran it for 20 minutes. Turned it off. Tried turning it on, CLICK. Hard to tell in the garage (had backed the car in) but there might have been a small, hardly visible amount of smoke come out from behind the batt (approx). It didn't smell electrical and may have been exhaust. "Service charging" came on again.
I'm going to take it over and have the alternator functionality checked.

Just read the voltage 2 minutes ago. 12.43 V. Pressed the starter button, CLICK.
Car has (2006 Coupe) 68,000. Starter has 38,000.
Also, when we found the loose neg cable that was the beginning of all of this, we changed the rear brake pads. The driver's door open switch (the one you squeeze to open the door) had been slowly failing. I swapped it with the passenger's. I disconnected it all together after new batt wouldn't start car second time.

I have included some details that obviously....most likely I mean, have nothing to do with the problem. They just happened to be done at the time this started.

So, other than the starter and the alternator, any obvious choices to check?

Oh, and my birthday was the day before.

Triumph Jerry

You have a new battery and low voltage, check to see if it's charging and if there is any big amp draw pulling the new battery down.
Happy Birthday.

brettbolt

I agree, but will add some details.

To test for amp draw, get a multimeter and set it to measure milliamps. With the car and all accessories off for several minutes, disconnect the battery cable and put one lead of the meter on the battery and the other on the cable.

The reading should be around 25 milliamps or less. If its much higher, there is a parasitic draw, and you can start pulling fuses until the milliamp reading is normal. That will tell you the cause.

As for the alternator, most auto parts stores will test them for free.

Chevy Cust Svc

TexasHiwayman,
Well, first of all. Happy Birthday! OK, back to business. This sounds like it could be several issues. You've essentially eliminated the battery as a cause since it's been replaced. This leaves a few options. Either your alternator isn't properly functioning. Or, you have a parasitic draw. There are also several other more obscure things that could be causing this. I'd recommend taking it to the dealership and having them take a look at it. Let me know if you'd like me to locate a dealership or setup an appointment for you.

Chevrolet Customer Service,
Justin

AORoads

disagree that w. a new batt. you've eliminated the batt. as a cause. was it fully charged up before or just after installation? you starting the car w. new batt., running 20 min., shut off and try to start it again and no start tells me the batt. wasn't fully charged when you put it in, right?

at 38K miles, I'd look at both the starter and the alternator as possibles, beyond finding any high drains.

KenHorse

I disgree

Just because a battery appears to charge and has a reasonable low or no load voltage doesn't mean it is good. Even load testing doesn't always tell the whole story.

Delco batteries use plates that are riveted together and a those are a very common failure point.

Bowtie_Brigade

Although rare, I did have a case where the main power lead to the starter had barely loosened up causing a similar type problem. I solved it by installing a lock washer. I'd check the leads just to be sure.

CO Lightfoot

You tightened the nut. But that doesn't mean the clamp is tight!

That is, maybe you have the wrong nut...

The C6 battery clamp is a special design that uses a unique cone-shaped nut.



A regular nut will hold the clamp in place. But it will NOT tighten the clamp.

Maybe someone lost the OEM cone-shaped nut and replaced it with a regular nut. It might work okay at first. But eventually, a regular nut will allow the clamp to get looser & looser, causing all kinds of problems: http://www.ls2.com/forums/showthread.php?t=846931

Unfortunately, finding a replacement nut is not so easy. Last time I checked, GM does not sell the cone-shaped nut as a separate item: http://forums.corvetteforum.com/c6-c...minal-nut.html

Anyway, you might need a new clamp... check for hidden corrosion.

AORoads

^^^good thinking and pics by CO to show the difference in design of the battery nut.

Jimmy W1

I don't think the starter would be the problem. You got the car started with the starter and once the car is started, it is not going to make your engine shut down like that out on the highway. Once the engine is running, the starter is no longer in the system to make the engine shut down unless the cable has come off and is being grounded against something. I would say you either have a short, an open or the alternator isn't charging. You need to fully charge the battery before you can check anything. And check it with a hydrometer. Testing the system with a battery that is bad or not fully charged will give you faulty readings. So, that is the number one thing to do before you do anything else. Then start the car, put a meter across the terminals and check the voltage. If the car won't start with a fully charged/good battery then you need to look at something else. I'm guessing that you have a bad alternator.