: car won't start. Need favor. What's your "ignition off" battery voltage?



cobrayankee
10-05-07, 07:18 AM
My car has been slow starting the last two weeks. Yesterday it finally stopped starting all together but then started again early this morning after clicking away for a few seconds. Now it's dead again. I have 9.2 volts showing. Is that normal with the car off or should it be higher? I'm guessing that's the battery saver causing it to read that low?
I'm hoping it's as simple as a battery but I can't tell. When it started back up again yesterday it showed a strong 14.4 volts at idle.
Also, the last month or so I have gotten in my car in the mornings and my time is reset to 12:00. :suspect: Has it gone completely dead over night???
In my searches I found that a few guys have had battery problems as early as 12,000 miles. Other than that I didn't find much else.
The worst part is that it's a nice long weekend for me and I'm supposed to be picking up new tires out west as well as some wheels from another member up north and I need my car for both.
Any help is appreciated guys.

RunningOnEMT
10-05-07, 07:22 AM
14.2 jeff

darkman
10-05-07, 07:25 AM
Your supposed to test the battery under load. In any event 9.2 volts is too low. Intermittent starting problems are almost always battery related. A weak battery will go dead overnight and will often fail to start the car when cold, but if "boosted" may start the car the rest of that day. Battery life is more dependent on other variables, e.g. heat, rather than mileage. The battery appears to be the most likely culprit in your case.

cobrayankee
10-05-07, 07:40 AM
I guess it's not going to hurt anything to replace it. I'll try to get out of here at lunch time and get someone to run me to Advanced Auto. Thanks for the quick replies guys.

The Tony Show
10-05-07, 09:29 AM
Also, voltage and cranking amps are unrelated. I've seen batteries showing 14.2 unable to even turn the car over, much less start it.

Fire and Ice
10-05-07, 11:41 AM
Most battery testers will show that under "starting" type loads 9ish volts is normal, but the battery should have 12v or higher when not in use. Typical voltage while the engine is running is about 14.2-14.5v. If you suspect battery problems, have a local shop do a load test on your battery. Sounds to me like you have a bad cell though.

Craig

Flyboy
10-05-07, 02:26 PM
Battery should be under warranty?????

ewill3rd
10-05-07, 08:53 PM
Key off the voltage should read in the 12.5-13.0 volt range. Each cell produces 2.1 Volts which should leave you with 12.6 volts but charging will usually leave it a bit higher.
If you have less than 10 volts you probably have a bad cell. One cell may have some damaged plates or a poor connection that is causing the battery to fail.
Delcos are notorious for holding a "surface charge" that will often fool testers after the car has been running.
After the car sits overnight it should still have over 12 volts in it.
If it doesn't you either have a current draw or a bad battery.
My bet would be a battery issue.

If the car is under warranty, the battery can be replaced by the dealer. They just have to get a test code out of it with a special battery tester.

cobrayankee
10-08-07, 04:44 PM
Thanks guys. I'm convinced it's the battery and was going to buy one but I made an appointment to get it serviced on Wednesday morning since the rear is leaking a little along with the coolant from somewhere. I'll get them to pay for the battery or at least troubleshoot it.
I think they'll have it for a couple of days.

CTSV_Rob
10-08-07, 06:00 PM
Let us know what you get after you put the new battery in. I'm curious what numbers you get when new.

I just checked mine last night and it was 11.8 with the key off and 11.6 with the key off and the low beams on.

Quick question ewill, (May be a stupid question and if so I apologize) How long can you listen to the radio before the car will not start? I listened to the radio for about 15 minutes and then tried to start the car and there was the familiar click. This was only about 4 Mo after I bought the car (new) but it still starts every morning (almost 1 year after purchase).

My car doesn't see the kind's of cold that you see though!

ewill3rd
10-08-07, 06:55 PM
Well that is an age old question with no really good answer.
Technically you would refer to the reserve capacity specification to calculate how long the battery can withstand a given load.
Reserve capacity on a 101 series battery is 110 minutes.

Reserve capacity is the amount of time in minutes it takes a fully charged battery, being discharged at a constant rate of 25 amperes and a constant temperature of 27C (80F), to reach a terminal voltage of 10.5 volts. Refer to Battery Usage for the reserve capacity rating of the original equipment battery.

So if it can handle 25 amps for 110 minutes you would think you could listen to the radio for half an hour.
You could have a weak cell. Delcos are notorious for holding a good "surface charge".
What this means to you is that the battery can actually be bad, but always start the car and usually test okay on our battery tester. Sad, but true.
The alternator keeps the charge up on the battery if it is driven regularly but if it sits, or the key is left on for a short while it will lose power fast and drop enough to where it won't start the car.
If I know the details of what is happening I can usually run a few tests that will show a bad battery that is doing this.

CTSV_Rob
10-08-07, 09:47 PM
Does this Radio really draw more then 50Amps or are you being a bit conservative?

I know when I put an amp in my car with a decent sub it would draw some serious current (<70Amps with the volume turned up) but I figured this one was closer to 25Amps at a comfortable volume.

This is great info and I think I will take an AMP clamp to the positive cable going to the battery to see how much it's drawing then see how long it takes before the battery goes completely dead.

It could just be my 15 minutes is closer to 30 minutes and this could be why the battery went dead.

BTW, By the time I get the "Battery Low" warning the car won't start. Is this because the limit is for the base CTS which I'm sure requires less current (Cold Cranking Amps) to start (lower compression, less cylinders...) or is this what GM intended? Not much of a warning if the car won't start when you get the warning, turning the key tells me the same thing.

I'm sure you have heard this many times but is there a better battery that fits into this car to give us a little more overhead?

Thanks much for the information.

ewill3rd
10-09-07, 06:54 AM
I think I have heard of guys trying a 78 series battery rather than a 101, I haven't tried it myself. There are lots of manufacturers of a 78 series battery out there and since it is under the hood you should have no install issues (as long as it fits in the tray).
Some guys are using optimas, but I'd advise staying away from anything that has top posts on it for that car. It is either going to contact the hood in some way or create an accident hazard. Some guys cut the posts off, but that doesn't eliminate the danger.

I am confident that the audio system is not pulling 50 amps, but I'd say the loads are probably between 20 and 30 amps with the key in accessory mode. I have an amp clamp but I probably won't have much time to do any data gathering for a while. I am going on vacation next week and I have to wrap up all the stuff I have going on in the shop inculding a rework of an XLR folding top. Lots of adjustments to make. ;)

Usually when the "battery saver active" or "low battery" message comes on, you are right... it is too late.

bpitas
10-09-07, 09:19 PM
If it's still under warranty, just let it die and then call roadside assistance and have them come out. I had a dead cell (battery was hot!) and they had one in the back of the support vehicle. The tech did a few tests, pulled one out of the back of the Denali, and put it in, all under warranty, in about an hour. After you change the battery you have to reset the window stops and a few other things, which is why it's nice to have the tech do it for you if you have that option.

-B

CTSV_Rob
10-10-07, 12:30 AM
I think I have heard of guys trying a 78 series battery rather than a 101, I haven't tried it myself. There are lots of manufacturers of a 78 series battery out there and since it is under the hood you should have no install issues (as long as it fits in the tray).
Some guys are using optimas, but I'd advise staying away from anything that has top posts on it for that car. It is either going to contact the hood in some way or create an accident hazard. Some guys cut the posts off, but that doesn't eliminate the danger.

I am confident that the audio system is not pulling 50 amps, but I'd say the loads are probably between 20 and 30 amps with the key in accessory mode. I have an amp clamp but I probably won't have much time to do any data gathering for a while. I am going on vacation next week and I have to wrap up all the stuff I have going on in the shop inculding a rework of an XLR folding top. Lots of adjustments to make. ;)

Usually when the "battery saver active" or "low battery" message comes on, you are right... it is too late.
No problem on the additional info, I will take care of it myself and if anyone is interested I will post the numbers. I am going to try and get it done this weekend.

Enjoy your vacation! (Sounds like you will need it after finishing the XLR top!)

ewill3rd
10-10-07, 06:49 AM
I got all the parts back from the body shop... going to try to get it done today. Not really looking forward to it.
I can't even tell you what a pain this is.
This poor lady lives kind of far away from here and has her car worked at by a dealer closer to her house. I guess she lets them work on it until it is all screwed up and then she brings it to me to fix it right ;)
LOL
Not to diss those guys down there, they do okay. This is just a really hard car to work on and I don't think whoever is doing it down there is fully trained on XLR.

We are leaving for Disney World on Sunday for a week.
Man do I need some time off!

cobrayankee
10-10-07, 08:54 AM
The car is at Cadillac now to look at the problem along with my e-brake, coolant leak, rear diff. leak, and peeling wheels. I'll probably see the car again on Friday I bet.

cobrayankee
10-10-07, 01:19 PM
Dealer confirmed the bad cell in the Delco battery. Warranty is paying for it. :thumbsup:
I had a bunch of problems that they're taking care of so I figured I'd throw some business their way and have them change the oil and fuel filter while they have it in there the next two days.