What was the voltage reading?

dghii,

So you are thinking that even though the alternator and regulator passed the tests at the local pepboys with flying colors, that could be the case? Their tests are not always accurate?

Jager,
I bought one of those battery/charging system testers from the auto parts store and with the car running on idle when I clamp the positive and negative, it comes up to around 13.4 or so(which is labeled in red on th meter. Green is above 14V). There is a load button on the tester also, when I push that, it drops to 12 V(slightly above maybe). Does that make sense?

I will post pictures when I get home tonight so it's clearer if I'm not able to explain it correctly.

Yes it does make sense, the voltage is a little low. What are your results when you connect your tester (-) side to the chassis (ground point) and (+) to the positive side of the battery and perform a load test?

So I did some more comprehensive tests and here are the results:

Battery Voltage with car sitting overnight: 12.2 V (seems slightly low but it is a brand new battery and the car hasn’t been taken out in over 2 weeks)
Battery Voltage when car starts up: 13.6-13.8V (Last night it was 13.6 and this morning it came up and showed 13.8 V actually)
Battery Voltage when the car has been running for a few minutes on idle: 13.6 V
Battery Voltage when headlights and blower are turned on: 13.4 V

Never went over 14V in my testing but do you think that if I drive it around a little and charge the battery more, it will? Or jut rev higher? If I had another person looking at it, it would be easier.

Interesting Observation: Not sure if this is normal, but I hear a slight hum from the front left side I suppose with the car turned off even and it goes away when I disconnect the battery. Is that normal?

I was not able to do the load test you asked for Jager because I was not sure what you really meant:

Turn the car on and hit the load button on tester with the (-)ve connected to chasis?
Or
Turn the car on and load using headlights and blower on with (-)ve connected to chasis?
Or
Leave the car off and do either of the above?

Thanks for all the support. What a great community. I hope that I can be of help to someone else in the future as well.

Amit

I should add one more thing- after the car runs for a few minutes and I shut it off, the battery reads at 12.6 V(which seems ideal).

Does that mean my battery is charging? Does that mean my meter is not the most accurate?

This piques my interest.

Yeah exactly, I just heard it this morning.

If I just walk up to the car, and put my ear against the front left without the key in the ignition even, there is a very very light humming noise. I wonder if that is the reason my battery drained in the first place and I wonder if that is why after sitting overnight, my voltage is at 12.2V instead of the 12.6 V after running the car for a bit.

Has anyone ever put a ear to their bonnet close to the battery? It would have to be in a quiet garage to hear the light hum.

Amit

I'm certainly no expert as I have my own issues that remain unsolved. A relatively easy thing to check may be the alarm horn on the right side of the battery when looking from the front. Maybe try unplugging it and seeing if the noise continues. I can't think of anything else that runs while the key is off.

It's probably not the cause, but it should take under 2 minutes to check.

Yes, turn the car on and hit the load button on tester with the (-) connected to chassis.

Jäger,

Did as you suggested. All tests with (-) connected to chasis. Here are the results:
Battery Voltage with car sitting overnight: 12.2v
Battery Voltage when car is started up: 13.8V(hovers between 13.7V and 13.8 V now)
Battery Voltage when load button is pressed: 12V

Car has not been driven in two weeks and I leave the terminals disconnected for fear of discharge, except the last 2 days when I have been doing these tests.

Thanks

I did not get a chance to look at this last night since I got home a little late after cheering on Team USA against Belgium(FIFA World Cup). Unfortunately, we lost the match last night but I must commend the strong fight we put up.

I did put my ear against that area and it seems like it is from that vicinity. I will have to remove the panels and maybe disconnect the alarm horn to confirm.

Amit

This just verified the (-) cable connection to your battery seems to be OK (corrosion problem area).
What is the voltage across the battery, motor running at idle, when you have all accessories (lights, radio (is it working?), AC, fan) turned-on?. As JFP mentioned earlier, it should not drop to 12.03 volts, that is an indication the alternator is bad. Did Pep Boys perform a load test on it?

I see. From my earlier test yesterday, Battery Voltage when headlights and blower are turned on: 13.4 V. Radio is not working since my battery first died and I got a jump.

I took the alternator outside the vehicle to pepboys and they just popped it in the machine in the back and did a test, they didn't really tell me what test but it sounded like basic functionality.

I will take it back to them installed in the car now and ask them to do a load test.

You are performing a load test by turning-on all the electrical accessories and measuring the voltage across the battery terminals. At 13.4V your battery is still getting charged.

I just thought of something... Does it change (drop) when the RPMs are increased??

Jager,

I just ended up taking it to a mechanic for inspection. He looked over it and his meter gave him a 14.2 V reading. Not sure what is going on but he said he does not really see any problems. I brought it home and figured I would give it a few days to see if it surfaces.

Meanwhile, since my radio keys arrived, I yanked the head unit out and sure enough, the fuse was bad, replaced it and all works well again.

I guess what killed my battery the first time will remain a mystery.. unless it happens again, at which point, I will do a full electrical systems test to rule out any other electrical problems.

Thanks for the suggestions everyone. If I can ever help with a similar problem, please send me a PM. Thanks.

Jager, what would it mean if the voltage dropped when load testing and increasing RPM?
Thanks

I have seen alternators on GM cars that had proper voltage at idle but the voltage would drop when RPM's increased... Bad alternator.

Figure out that hum?