2018 3.6L JLU charging voltage question

[DirtRoad]

I took a long trip (about 6 hours each way) last week and in the past I've noticed on long drives my charging voltage will go down steadily until it hits around 12.7 volts when the batteries are fully charged. On this trip it never went below 14.1 volts. Is this a sign my ESS battery is dying?

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[Yellow Cake Kid]

It could be a sign that you were running the AC, listening to your stereo, powering the LCD display, charging a phone... or two, etc.

It is correct to think that the charging system can reach a state where the battery is fully charged and the voltage shown in the dash display will drop below 14vDC, but if during your drive the demand for power is great enough the Jeep will continue to serve the system with the alternator providing a robust output.

Having said that, your initial supposition may be correct, but as mentioned above, not necessarily so.

If you really want to know the answer, you will need to measure the battery directly, preferably while it is out of circuit, and likely in multiple instances, before you will have enough information to make an informed decision.

 

[DirtRoad]

Well, I still need to do some more checking but today I let the ESS turn the engine off and it lasted about 15 seconds before the voltage dropped from 12.6 to 12.2 volts and it started the engine back up. I usually turn the ESS off as soon as I start the Jeep, especially in the summer here to keep the a/c running. The fan was on about 3 and the radio was on but that was about all the electrical load it had. Seems like the ESS battery used to hold out a lot longer than that - not a lot longer but a couple minutes anyway.

As far as I know, my Jeep is one of the early ones that'll leave me stranded if the ESS battery dies. It's still under warranty though so should I take it in early and try to get them to fix it a little pre-emptively or wait until it won't start?

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