Fluctuating volatge at idle

[dbrown]

When driving, I’ve started to notice that when I come to a stop light, my voltage fluctuates from around 14.2 down to around 12. It sounds like the engine struggles to idle, then will ramp back up and sound fine. It’s only a year old, so hard to think it’s a battery already, but concerned about it nonetheless. Seems to be worse in the morning when it’s cold outside. Alternator? Normal?

 

[Robr651]

The OEM batteries are junk. Disconnect it and check it with a battery tester. I swapped mine out within 2 years as have many others. Some have had the dealer swap it under warranty. I didn’t want to waste my time at the dealer and my replacement has a 4 year warranty.

 

[dbrown]

That was sort of my thought as well; I had them test the battery at AutoZone, but I really don’t think the kid doing it had any idea what he was doing

 

[Firedude]

Mine has done this since new. Im going with normal.

 

[BarneyM]

When driving, I’ve started to notice that when I come to a stop light, my voltage fluctuates from around 14.2 down to around 12. It sounds like the engine struggles to idle, then will ramp back up and sound fine. It’s only a year old, so hard to think it’s a battery already, but concerned about it nonetheless. Seems to be worse in the morning when it’s cold outside. Alternator? Normal?

How old is your battery? My 2022 was doing something similar. I replaced the battery problem solved. May not be your problem but was mine.

It helps if you put the year of your Jeep somewhere in your post.

 

[Bobo57]

My stock battery took a crap about 14 months. No warning whatsoever, one minute starting and running normal, stop for 15 minutes totally dead. No dash lights, nothing...........
When that happened I did not observe any fluctuation in voltage behavior nor do I see that now. Interesting.

 

[hardhat]

The fluctuation at idle is likely the electric steering. Mess with steering wheel and you can provoke it.

 

[great one 99]

When driving, I’ve started to notice that when I come to a stop light, my voltage fluctuates from around 14.2 down to around 12. It sounds like the engine struggles to idle, then will ramp back up and sound fine. It’s only a year old, so hard to think it’s a battery already, but concerned about it nonetheless. Seems to be worse in the morning when it’s cold outside. Alternator? Normal?

normal

 

[Changster]

The OEM batteries are junk. Disconnect it and check it with a battery tester. I swapped mine out within 2 years as have many others. Some have had the dealer swap it under warranty. I didn’t want to waste my time at the dealer and my replacement has a 4 year warranty.

Just been through this same issue. Went away for 2 weeks. 392 Just barely started. one morning had to call out AMA. Bought a jump starter. Took it back to Jeep and the battery was a dud. Replaced in FoC and now back to normal. Excellent Jeep service but clearly these stock batteries are pants.

 

[Bacon392]

Check all of the connections at the battery. I had this problem and it turned out to be that a pressed threaded post had wobbled loose on the positive terminal . It had generated heat and even melted the red silicone cover.

Once I replaced the terminal, the problem went away completely.

Regards,
Mike

 

[Firedude]

Again, this is normal for the new alternator systems.

 

[Bacon392]

Again, this is normal for the new alternator systems.

“It sounds like the engine struggles to idle”

This is 100% not normal.

 

[BarneyM]

Again, this is normal for the new alternator systems.

Mine does not do it.

 

[Firedude]

Actual experience here. Doing some research can confirm also.

 

[Firedude]

Not the idle struggling part but it does change slightly.

 

[Bobo57]

My 23' fluctuates maybe 0.1-0.2 volts.........................

 

[Dadstion]

I've had the same voltage behavior in our 2024 since new. So if replacing the battery is the best solution, which are the best as replacements? I've heard positive comments from hardcore off-roaders about Antigravity Batteries (lightweight but expensive). Your experience and feedback are welcome.

 

[Rusty762]

Had the same experience in my 2023 392 about 4 months ago. Bought a Platinum AGM with 5 year warranty from O'Reillys and no issues since.

 

[johnsjav1!]

Have the same behavior on my 2022. Checked with the dealer and was told the alternator is clutched and the voltage will fluctuate. This is normal. Told me that if it's not fluctuating, the battery is on it's way out.

 

[Rusty762]

Have the same behavior on my 2022. Checked with the dealer and was told the alternator is clutched and the voltage will fluctuate. This is normal. Told me that if it's not fluctuating, the battery is on it's way out.

I have never been to a dealer and never would listen to anything they say as most barely know how to put gas in their vehicle. My voltage stays right at 14 with new battery, when I noticed it dropping from 14-12 regularly and even though I keep it plugged into a Noco Battery conditioner one morning when I went to turn it over nothing. It was my own fault for waiting to replace what I already knew was a shit battery from the factory...