12v Battery Warning Light; Low Voltage While Driving?

Johnb300m · Sep 11, 2025

Hey folks, I had my 12v battery replaced in late July, where the dealer confirmed it was a faulty battery, that tested so.
They replaced it with another OEM and sent me on my merry way.
Things were fine since then, until last night.
I stopped at the gym after work and was sitting for about 1min in the parking lot with ignition on.
A 12v battery CEL then came on with the chime. I checked the voltage in the gauge summary, and voltage read 12.3V.
I shut down the vehicle, opened the door for a minute, turned ignition back on, and the voltage read 14.2V, which seems typically normal for "ignition ON."

Driving home after the gym I monitored the gauges, and noticed that the 12V system would seesaw, about every 4-6minutes, from 12.6V to 14.2 - 14.8 during the whole drive.
The 12V battery CEL never returned, but I thought this was very weird.
It's my understanding that during Ignition ON, the system should be at ~14V.
But now it's going up and down.
I wonder if this issue was hidden before and might have contributed to the death of my first battery? IDK.
I have another......sigh.....dealer visit in the morning on Fri. We'll see what they find this time.
Photos attached:

Billi · Sep 11, 2025

Need to check your battery when car is off.

Chances are your 'newer' OEM battery is also a bad one.

Johnb300m · Sep 15, 2025

Summary: Inconclusive.
A very nice technician at the dealer went through everything with a fine tooth comb, checking grounding connections, wire harnesses, flashing some software, and a test drive.
It's inconclusive, and the battery test passed.
He said that with the 4xe it's not uncommon for the voltage to swing up and down from 14V with ignition-on. Which is weird since I've never noticed it do that before.
But as long as it's properly charging the 12V battery, which he said it is, it should be ok.
What he doesn't know is if the battery itself is maybe on the verge of failing? He can't tell because the test kept passing. But it's up to me to monitor it now I guess.

Interesting anecdote he had was, that their location sees far more failed 12V batteries on the Wagoneers and gas GCs, vs the 4xe.
Mine was the rare 4xe he's seen with 12v issues, most that he's worked on are high voltage battery issues (which was not encouraging either).

Clutch Auto Deals · 2025-09-15T19:58:30-0400

Johnb300m said:
He can't tell because the test kept passing.

A proper load test on a 12v battery can take a few hours to run. If he is doing a quick voltage test, it can very easily give a false positive for battery health.

I would expect a failure soon on your 12v based on these symptoms.

Billi · 2025-09-15T23:45:31-0400

If it fails again, I wonder if consumer could ask Jeep for a monetary compensation, so that we can buy a battery from another brand, rather than having a warranty replacement of the same lousy battery?

Johnb300m · 2025-09-16T11:13:35-0400

At this point I will happily have them put 8 new batteries in my vehicle.
On THEIR dime.
Financial stress is the only way companies like Stellantis will act.

12v Battery Warning Light; Low Voltage While Driving?

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