spiking voltage 2012 Elantra

[schuylkill]

Because I do Fas daily (but not frequently) I keep my eye on the voltage display on my ultra-gauge when the engine is off. I know the voltage is normally about 14.5 when I'm cruising. This afternoon when leaving work I started my car and an alarm for high voltage sounded (over 14.9 volts I believe is the default number for the alarm on the UG.) The voltage quickly went down to 14.68 and it bounced between 14.58 and 14.68 and settled at 14.58 where it remained for the drive to my son's CC , about 25 miles. After picking him up and starting the car again once again the alarm and again quickly back to 14.58v. I turned the car off twice on down hills and the voltage went down to about 12.3 and then back to 14.8 on start up and again settled at 14.58. When I got home I turned the car off a couple of times and started it and the voltage went up to 15.1 once and 15.0 and then back down.

I think my alternator is failing. Once I cooked a battery in my 98 civic, which has no gauges, and I found out by smelling "rotten eggs" and finding my battery steaming when I popped the hood. That alternator had hundreds of thousands of miles on it.

Just went to maniacelectricmotors.com (good parts place) and according to their test info (http://www.maniacelectricmotors.com/chstsycivote.html) up to 15.1 volts is normal. I guess I'll keep an eye on it for now. Something is different though because the alarm never sounded before.

Any suggestions?
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[oliveoil]

Don't worry, it's under warranty.if it dies take it to the dealer. Yet the range sounds fine to me.

 

[crazyoildude]

Keep us posted as to what the stealer says...

 

[JHZR2]

if your battery is only 12.3V sitting, it is too low. but get a meter and really check it.

14.9 is a bit high, even if below 32F at the alternator, but unless it is really in the solid 15 range, i wouldnt worry.

 

[The Critic]

My Prius does the same per the live data I see in Techstream.

 

[Rand]

What is Fas?

Sounds borderline normal. I'd proceed with observation but not worry much. Measuring at the alternator is higher than measuring at the battery.

 

[schuylkill]

Quote:
f your battery is only 12.3V sitting, it is too low. but get a meter and really check it.


Measures 12.44 at the battery. What's all the fuss with fuses and cables and whatever going on at the battery? I'm going to look at the owner's manual.

Quote:
What is Fas?


Forced auto stop I believe it is. Keying off the car then back to power without the engine running while coasting at steady low RPM.

 

[mechtech2]

Seems fine to me.
Remember that cold voltages are higher, and are supposed to be higher.

 

[schuylkill]

Quote:
Remember that cold voltages are higher, and are supposed to be higher.


It was 34F when this occurred. I've started the car at 9F and in the teens without this issue, so something seems different and therefore my concern. I looked at the battery setup today when I measured v at the battery. The new Hyundais use a smart alternator setup and there is really a lot going on at the battery. I really need to get a shop manual on the car.

 

[91344George]

Originally Posted By: schuylkill
[
It was 34F when this occurred. I've started the car at 9F and in the teens without this issue, so something seems different and therefore my concern. I looked at the battery setup today when I measured v at the battery. The new Hyundais use a smart alternator setup and there is really a lot going on at the battery.

I really need to get a shop manual on the car.



Study up all you want, certainly not a bad idea for reference and future potential issues, BUT DO NOT TINKER with the system yourself, you are under warranty and car makers today love to void warranties at the drop of a hat if unauthorized work has been done, including testing.

 

[mechtech2]

Some cars have the regulator in the main computer.
I hope yours doesn't!

 

[SHOZ]

It will always be higher after starting as it is replenishing the juice that was used to start.

 

[Nick R]

My battery voltage hits 15V during highway and town cruising sometimes. It fluctuates between 13.8 and 15, usually around 14.4-14.6V. I'm not concerned at all.

 

[SHOZ]

It will always be higher after starting as it is replenishing the juice that was used to start.