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I have my 2005 Corvette. 33,000 miles. Yesterday I had it out for only the 2nd time this year. When I went to put it in the garage, I could hear the alternator making a humming noise that was a little louder than normal. The gauge on the dash read 13 volts, even with the lights and AC on. I put a meter across the battery and it carried the load ( AC and lights) at 14 volts. But the voltmeter on the dash continued to read 13 volts. The battery is four years old and I am thinking it is going bad. I have had a trickle charger on it all winter. I had no trouble starting the car yesterday. I am going to go out and check it again in a little while. I am hoping it is the battery. A lot easier and cheaper to change. What do you think?
I have my 2005 Corvette. 33,000 miles. Yesterday I had it out for only the 2nd time this year. When I went to put it in the garage, I could hear the alternator making a humming noise that was a little louder than normal. The gauge on the dash read 13 volts, even with the lights and AC on. I put a meter across the battery and it carried the load ( AC and lights) at 14 volts. But the voltmeter on the dash continued to read 13 volts. The battery is four years old and I am thinking it is going bad. I have had a trickle charger on it all winter. I had no trouble starting the car yesterday. I am going to go out and check it again in a little while. I am hoping it is the battery. A lot easier and cheaper to change. What do you think?
I would trust your voltmeter more than the gauge in the car. Doesn't sound like you have a problem to me other than a suspected noise maybe. Monitor it but I wouldn't sweat it just yet. Also the alternator is a breeze to change on these cars, probably just as easy as the battery so dont sweat that either if that does end up being the case.
As you can see in the picture my DIC shows about 0.74 volts lower than at my battery with my AC and lights on…by the time voltage gets from the battery through fuses, wiring, connectors etc you will have a slight voltage drop…the DIC voltage comes from Ignition 1 voltage which there are 4 of them coming from the BCM…with a factory level scan tool you can check this Ignition 1 voltage…you should have your battery load tested anyway if it is 4 years old.
So, I went to O'Reilly's today and got a battery hydrometer. I came home and checked all of the cells in the battery and they all check in the good area and they all read exactly the same. So, that tells me the battery is okay. I have another voltmeter and I thought I would put it on the car and check the system again. With the AC on, headlights on high and a Van Halen CD going, the external voltmeter and the voltmeter on the dash both read exactly 14 volts and the system carried the load. And the sound on the alternator had diminished quite a bit......... I had just gotten back yesterday from a long drive- about 40 miles, and it was right at 100° out. So maybe the heat caused it to act up. I doubt it, but that is all I can think of. I have a feeling that maybe a bearing in the alternator might be going out. So, I will just have to keep an eye on it. Thanks for the help gentlemen. I really appreciate it. I will be shaking my head for a while I guess. 🙃
So, I went to O'Reilly's today and got a battery hydrometer. I came home and checked all of the cells in the battery and they all check in the good area and they all read exactly the same. So, that tells me the battery is okay. I have another voltmeter and I thought I would put it on the car and Catherine system again. With the AC on, headlights on highand a Van Halen CD going, the external voltmeter and the voltmeter on the dash both read exactly 14 volts and the system carried the load. And the sound on the alternator had diminished quite a bit......... I had just gotten back yesterday from a long drive- about 40 miles, and it was right at 100° out. So maybe the heat caused it to act up. I doubt it, but that is all I can think of. I have a feeling that maybe a bearing in the alternator might be going out. So, I will just have to keep an eye on it. Thanks for the help gentlemen. I really appreciate it. I will be shaking my head for a while I guess. 🙃
Don’t bother with a hydrometer !!…that is something we did back in the 60’s !!…we now have electrical equipment to load test it…do that !!
Don’t bother with a hydrometer !!…that is something we did back in the 60’s !!…we now have electrical equipment to load test it…do that !!
Yes. I was an automotive electrician back in the early 70's. 🙂 Back then we had a meter to put a load on a battery, but I don't have one at the moment.. I'll wait and see. But thanks. 👍
Last edited by Jimmy W1; Jun 17, 2024 at 03:14 PM.
Yes. I was an automotive electrician back in the early 70's. 🙂 Back then we had a meter to put a load on a battery, but I don't have one at the moment.. I'll wait and see. But thanks. 👍
Take it to Auto Zone, they’ll do a load test on it for free, O’Rilley’s might do it for free also.
Charging Problems?
