Battery Voltage Too Low?

[Rival///]

i would have expected the battery voltage to be around 14V while cruising, I’m getting 12.6-12.9V. Any thoughts or experienc?

(West Texas…speed limit is 80MPH).

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[BDinTX]

I see similar numbers, occasionally going up to 14.1v.

Aux battery deleted, diesel, 2021. It’s a little disconcerting but has been like that for as long as I can remember.

 

[Heimkehr]

i would have expected the battery voltage to be around 14V while cruising, I’m getting 12.6-12.9V. Any thoughts or experience?

12.8V is just above what I'd consider a healthy resting voltage when the vehicle is parked and off...but not when driving (at any speed.)

If you've the original battery in your '19, consider this a possible sign that it's nearing the end of its practical service life.

 

[Rival///]

12.8V is just above what I'd consider a healthy resting voltage when the vehicle is parked and off...but not when driving (at any speed.)

If you've the original battery in your '19, consider this a possible sign that it's nearing the end of its practical service life.

i need to update the profile. New to me 2022 Diesel. Fresh battery prior to purchase.

 

[Heimkehr]

i need to update the profile. New to me 2022 Diesel. Fresh battery prior to purchase.

Provided the battery was indeed recent production and correctly sized for the vehicle, the next step is to test the alternator.

 

[ssls6]

I think the battery management system turn the alternator nearly off to save fuel when it can. I've noticed if I charge my batteries fully then I'll see 12.6-12.8 ish on the dash display. If I don't and use the starter to prime the oil canister, then I'll see 14 ish volts after starting.

 

[Gorilla57]

It's totally normal......."smart" alternator is saving you fuel. Also means your battery is healthy if the system shuts down the charging.

 

[zouch]

congrats on the Diesel! low mileage, too!


i hope when you wrote "battery" you meant "batteries"; you want to replace them both together because one going bad will drag down the other.
fortunately it's easier to access the Aux Batt in the Diesel than in any other configuration; the Aux Batt is in a nice little compartment under the Main Batt accessed via a little trap door. just remember to rest the IBS after you've reconnected Batts and expect it to take several full Cold Starts before Voltage begins to be reported as normal.
there are also volumes written here about how to Delete that pesky Aux Batt, if you're interested.

if you search on this forum you should be able to find reams of detail about the charging systems on these thing; they'll charge hard (up to 14.4/14.5V) when coasting down or when the batts are not fully charged, and that Voltage will drop down a couple of Volts lower once they're charged up, so reported Voltage regularly fluctuates.

(unrelated to your question,) what i want to know is; why are you in Manual 8th gear at that speed?
why not just leave it in D and let that awesome 8HP75 trans do its thing?

i need to update the profile. New to me 2022 Diesel. Fresh battery prior to purchase.

 

[Suffolklou]

What they said

 

[mtnmerlin]

12.x volts is normal once the battery is fully charged. It will be at 14v when the battery is charging.

 

[grimmjeeper]

Totally normal. I see mine in the upper 12.x range to 14.x depending on state of charge on the battery.

 

[Rival///]

Thanks for all the responses, makes sense.

 

[Rival///]

(unrelated to your question,) what i want to know is; why are you in Manual 8th gear at that speed?
why not just leave it in D and let that awesome 8HP75 trans do its thing?

Long story but just picked it up and started my 16 hour drive home. 3 hours in it went into limp mode, dash lit up and lost power. Would only run 45MPH max somewhere in no man’s land between Arizona and New Mexico. That’s a very sick feeling.

Right or wrong, my logic was it wasn’t doing an active regen for some reason and so I finally got RPM’s over 2,500 RPM and power came back. My thinking was it would passively regen at that condition. So, every once and awhile, and hills, I would drop it to M7 and hold RPM’s up. Made it the rest of the way home successfully.

Going to drive it this week and see if it does it again. I put it in Drive the last 2 hours without incident. Maybe a fluke?

 

[zouch]

i know the area you're talking about; played all over there (and family has a house in NB).

i doubt it's anything as esoteric as Regen related; i'd be thinking Fuel Filter, and really quick. did you read any Codes off of it (DTCs)?

looking at a vehicle that's a couple+ years old already and only has 10K miles on it, i'm thinking it sat a good bit, and fuel had time to get old and rotten in it. first thing i'd be doing at this point (and quickly) is changing Oil, Oil and Fuel Filters; would probably be changing Fuel Filter again pretty soon just for good measure.

you probably already know the CP4 High Pressure Fuel Pumps in these things can be finicky; i'd be mighty concerned about anything that affected Fuel delivery to that CP4. when one of those pistons in the HPFP rotates and it starts spewing metal shavings through your fuel system, you won't be sputtering, you'll be sitting still without warning. and if yours has already been in for the Recall, you're risking being on your own at footing the cost of replacing the entire Fuel System.
if it hasn't had the CP4 recall done yet, i'd look into it quickly.

Long story but just picked it up and started my 16 hour drive home. 3 hours in it went into limp mode, dash lit up and lost power. Would only run 45MPH max somewhere in no man’s land between Arizona and New Mexico. That’s a very sick feeling.

Right or wrong, my logic was it wasn’t doing an active regen for some reason and so I finally got RPM’s over 2,500 RPM and power came back. My thinking was it would passively regen at that condition. So, every once and awhile, and hills, I would drop it to M7 and hold RPM’s up. Made it the rest of the way home successfully.

Going to drive it this week and see if it does it again. I put it in Drive the last 2 hours without incident. Maybe a fluke?

 

[Rival///]

i know the area you're talking about; played all over there (and family has a house in NB).

i doubt it's anything as esoteric as Regen related; i'd be thinking Fuel Filter, and really quick. did you read any Codes off of it (DTCs)?

looking at a vehicle that's a couple+ years old already and only has 10K miles on it, i'm thinking it sat a good bit, and fuel had time to get old and rotten in it. first thing i'd be doing at this point (and quickly) is changing Oil, Oil and Fuel Filters; would probably be changing Fuel Filter again pretty soon just for good measure.

you probably already know the CP4 High Pressure Fuel Pumps in these things can be finicky; i'd be mighty concerned about anything that affected Fuel delivery to that CP4. when one of those pistons in the HPFP rotates and it starts spewing metal shavings through your fuel system, you won't be sputtering, you'll be sitting still without warning. and if yours has already been in for the Recall, you're risking being on your own at footing the cost of replacing the entire Fuel System.
if it hasn't had the CP4 recall done yet, i'd look into it quickly.

I think you’re right on the aged fuel. Has been driving great and soot load is currently around 23%. So it’s definitely regenerating.

It just had the recall performed but not prior failure so maybe they didn’t drain the tank.

This Jeep changed hands through two dealerships just ahead of me acquiring it with the first being a Jeep dealer to perform recall where they also changed oil and filters. However it then went to a used car dealer where I have less confidence that they used the correct spec oil so I did change it right away to be certain. I’ll change the fuel filter this weekend and the. Again after a few more tanks before getting back on the regular interval.

It’s running strong and no CEL, hoping to keep it that way! Thanks for the insight!

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