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The thing that had me concerned is the 13.4 wasn't a fluke. I was running at 13.4-13.8 consistently while cruising at highway speeds (70-80 mph) during the day in triple digit temps. I was just out for a drive trying to find a shop to do a load test, and I was seeing it drop down to as low as 12.6 at a steady 45 mph @ close to 2k rpm. Unfortunately, it looks like I'm going to have to wait until next week when I can get by my buddy's shop after work to have it load tested.
If it was a cracked wire winding in the alternator, then the problem does not self correct.
With the amount of heat, still say to clean up the OEM before you replace it, and go through the charging wiring system connectors to make sure that it was not heat induced connector problem.
Hell who knows, and may find that the problem is just a cracked bakelite starter solenoid cap/terminal problem that was causing the problem in the high heat, and just need to replace the starter solenoid isntead.
If it was a cracked wire winding in the alternator, then the problem does not self correct.
With the amount of heat, still say to clean up the OEM before you replace it, and go through the charging wiring system connectors to make sure that it was not heat induced connector problem.
Hell who knows, and may find that the problem is just a cracked bakelite starter solenoid cap/terminal problem that was causing the problem in the high heat, and just need to replace the starter solenoid isntead.
That does make sense, and this is some good advice. Guess I'll plan on spending time under the hood next weekend cleaning the connections and inspecting the starter solenoid. I'm prepared to spend the money on a new alternator if I have to, but I'd really prefer not to, which is why I decided to ask here before throwing money at the problem. I'll post an update next week after I finish.
Just about all auto parts stores can test your Alt and battery, on or off the car. Results can be mixed, I went to 3 that were in the same block....1 said Alt was in working order, 2 said it failed their test.
I have over 130k miles on my original alternator and my car, an 07 completely stock, exhibits the symptoms yours does on occasion when really hot.
I don't think what you are experiencing is unusual with your combination of aftermarket audio/heat. I wouldn't worry about it until it actually failed.
I have over 130k miles on my original alternator and my car, an 07 completely stock, exhibits the symptoms yours does on occasion when really hot.
I don't think what you are experiencing is unusual with your combination of aftermarket audio/heat. I wouldn't worry about it until it actually failed.
Would take the 20 mins to pull the alternator, pull it apart to clean up it and in contact points up, as well as may just change out the brushes while you have it open as well.
The brushes are less than $10, and only take a min to re-solder the new ones back into the old brush housing.
Battery tested just fine, and as I mentioned, the system appears to work normally when temps are in the 80-90 range. It's the triple digit temps that seem to be the primary cause. I do plan on load testing the system before I make a final decision, though.
perhaps so. So if the battery checked good, did the alternator check bad? Yep, it's really hot and that kills batteries.
I've been bothered by Evap codes and TPMS codes for nearly a year. After I changed battery the (Evap) engine light turned itself off. I have to wonder if those TPMS sensors were bad?
perhaps so. So if the battery checked good, did the alternator check bad? Yep, it's really hot and that kills batteries.
I've been bothered by Evap codes and TPMS codes for nearly a year. After I changed battery the (Evap) engine light turned itself off. I have to wonder if those TPMS sensors were bad?
A new battery is $120. Cheap.
My battery is new. Just bought it a few months ago.
'05 A4 Z51 with 31K miles, I've had similar issues with low voltage showing on the DIC. First thing, listen to Dano, he one of the smartest guys on here when it comes to charging systems, electrical and is always willing to help with good advice. I've had times when, sitting in heat with everything going the DIC showed 11.5-12 at idle, drove my crazy. I haven't had the time to go through the car and clean all the grounds as Dano suggests but I did have my alternator checked recently at a reputable repair/rebuild shop and all is good, the shop owner said it was working just like it was supposed to, he said these alternators are usually good for at least 75K miles. I also explained my (your, our) issue to my mechanic, a VERY well respected Vette guy in this area and he said the same thing, this is completely normal for our cars, just a quirk of the C6's. Until something drastic happens I'm gonna clean the connections and leave it alone...good luck!
'05 A4 Z51 with 31K miles, I've had similar issues with low voltage showing on the DIC. First thing, listen to Dano, he one of the smartest guys on here when it comes to charging systems, electrical and is always willing to help with good advice. I've had times when, sitting in heat with everything going the DIC showed 11.5-12 at idle, drove my crazy. I haven't had the time to go through the car and clean all the grounds as Dano suggests but I did have my alternator checked recently at a reputable repair/rebuild shop and all is good, the shop owner said it was working just like it was supposed to, he said these alternators are usually good for at least 75K miles. I also explained my (your, our) issue to my mechanic, a VERY well respected Vette guy in this area and he said the same thing, this is completely normal for our cars, just a quirk of the C6's. Until something drastic happens I'm gonna clean the connections and leave it alone...good luck!
I'd already planned on following Dano's advice and cleaning all of the connections this coming weekend. I'd have done it this past weekend, but needed to clean up the aftermath of my vert's first time driving in the rain. Got stuck in an unexpected rain storm Friday on my way home. First time I've used my windshield wipers.
Do you have a capacitor in-line for your amp??? This will make a BIG difference here and the amp will draw power from the capacitor vs the battery
This isn't exactly true. While it really is unrelated to this topic, I need to clarify this because it bugs me. An audio amplifier is a live load. In other words, it's current draw isn't constant. In the case of a hard hitting, low frequency amp, even more so.
What a capacitor will do for the amp is provide momentary spikes of current during the highest load times. The internal resistance of a capacitor, local to the amplifier, is much lower than the battery's and so it, along with a diode, can provide a much more stable voltage to the amp if the cap is sized correctly AND the power supply (in this case the battery and alternator) can supply enough current, on average, to keep the cap charged.
If the alternator and battery are weak or other appliances are drawing more current than the alternator can provide, the battery does it's best to make up the current at the cost of voltage dropping. Age, heat and load all play a part in how much current a battery can deliver. The battery's other responsibility, to smooth the pulsating DC from the alternator can also play a factor, especially if one of the diodes in the alternator is weak and compounding the issue.
My point to all of this is that a capacitor, while an appropriate part of an audio system to bolster sound quality, won't band-aid a failing charging system. Without adequate current from the alternator/battery the cap eventually becomes ineffective. There is no free lunch when it comes to electronics.
'05 A4 Z51 with 31K miles, I've had similar issues with low voltage showing on the DIC. First thing, listen to Dano, he one of the smartest guys on here when it comes to charging systems, electrical and is always willing to help with good advice. I've had times when, sitting in heat with everything going the DIC showed 11.5-12 at idle, drove my crazy. I haven't had the time to go through the car and clean all the grounds as Dano suggests but I did have my alternator checked recently at a reputable repair/rebuild shop and all is good, the shop owner said it was working just like it was supposed to, he said these alternators are usually good for at least 75K miles. I also explained my (your, our) issue to my mechanic, a VERY well respected Vette guy in this area and he said the same thing, this is completely normal for our cars, just a quirk of the C6's. Until something drastic happens I'm gonna clean the connections and leave it alone...good luck!
I agree, showing 11.5 - 12 at idle with AC and everything else running shouldn't be alarming.
From days of yore: One reason they switched from generators to alternators is that generators would not produce enough current at idle, and the GEN idiot light would flicker -- meaning it was drawing some power from the battery also, because the generator couldn't keep up.
Alternators eliminated that. However, with AC being on nearly every car now, along with high current-drawing sound systems and other accessories that didn't used to exist, sometimes alternator output is marginal. So in extreme conditions, apparently it will draw some current from the battery.
If that's what it is, and I have this right, then it isn't anything to worry about (we wouldn't even know about it except for the DIC staring us in the face, tempting us to press the button ).
The battery is being used a bit more than it would be otherwise, but assuming everything else is up to snuff (alt output, ground connections) once you're off idle for a while it should charge back up to normal.
This isn't exactly true. While it really is unrelated to this topic, I need to clarify this because it bugs me. An audio amplifier is a live load. In other words, it's current draw isn't constant. In the case of a hard hitting, low frequency amp, even more so.
What a capacitor will do for the amp is provide momentary spikes of current during the highest load times. The internal resistance of a capacitor, local to the amplifier, is much lower than the battery's and so it, along with a diode, can provide a much more stable voltage to the amp if the cap is sized correctly AND the power supply (in this case the battery and alternator) can supply enough current, on average, to keep the cap charged.
If the alternator and battery are weak or other appliances are drawing more current than the alternator can provide, the battery does it's best to make up the current at the cost of voltage dropping. Age, heat and load all play a part in how much current a battery can deliver. The battery's other responsibility, to smooth the pulsating DC from the alternator can also play a factor, especially if one of the diodes in the alternator is weak and compounding the issue.
My point to all of this is that a capacitor, while an appropriate part of an audio system to bolster sound quality, won't band-aid a failing charging system. Without adequate current from the alternator/battery the cap eventually becomes ineffective. There is no free lunch when it comes to electronics.
I read thru the entire thread and this post and sentence jogged my memory. From way long ago, some of you will remember Paul "talon90". He told me that the C6 was designed to be as light as possible and that meant a lot of components and systems were the opposite of "maximized"---meaning, they were minimized. One of them was the under-hood, charging/starting system to save weight. This would include the batt., alternator, starter, etc. I think many have suffered with batts. that go dead after a few weeks (many/most don't, but my 3 mos. old NCM-delivery did so in my garage w/o a tender).
So, take it for what it's worth and this is an excellent thread w. comments from all and Dano.
Would take the 20 mins to pull the alternator, pull it apart to clean up it and in contact points up, as well as may just change out the brushes while you have it open as well.
The brushes are less than $10, and only take a min to re-solder the new ones back into the old brush housing.
I drove into work again today. With A/C on and radio blasting it was running 14.0-14.2 at highway speeds at just over 80 degrees. At stoplights the lowest it dropped to was 13.4. I'll keep an eye on it on the way home today as it will be triple digit temps with the heat index, but it's definitely looking like heat is my problem, and that the system itself is working just fine. I still plan on cleaning all of the connections this weekend, though, as I'm sure there's some oxidization of the metal and I want to see what the starter solenoid looks like.
The whole point of this thread was to determine whether or not I really need a new alternator, and how to avoid having to purchase one if possible.
Corvette_Ed,
I'm in Plano, so in your neck of the woods. I've had my '07 Vert for a couple of months now, and mine behaves exactly like yours. I did lots of research on this on here and the web and I was fully prepared to buy a new aftermarket alternator just to avoid any headaches, but it seems like this is all normal. An electrical engineer (claimed to be) on another site said that it's normal for the car to show 14.2-14.4 on start up for a few and then eventually drop down a little as the car warms and the battery charges. The Texas heat does take a toll on our batteries for sure. I don't daily drive mine, but make sure to drive it at least a couple times a week, just to make sure it's getting some charge, fluids are flowing etc. I'm also one of the OCD drivers that opens the hood once parked in the garage to let it cool off faster. At least it does in my mind! Lol! I did notice that the alternator stays hot way after the rest of the engine has cooled down. Anyway, I'm going to stay with mine for now and try not to OCD on it too much!
07-15-2017, 02:59 PM
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