Voltage

[ShadowsPapa]

My jeep idles/drives at 14 volts all day every day. They checked my battery when I had my tires installed (Firestone complimentary service) and said it was good. You’ve just reminded me to check the voltage on it after it’s been sitting a while.

It is going to depend in the driving you do - or don't do.
If you never drive more than 30 minutes a day one way, or if it sits every other day, you'll never get the batteries to 100% and yeah, you'll see 14 volts most of the time.
When the batteries are FULLY charged, 100% SoC and the engine is under load, it can drop back to 12.6 for example, then up again to around 13 when you go down a hill and let off.
But if it's staying at 14+ all the time, then they are never fully charged.

I guess I'd be worried that if the alternator is constantly running at that higher state, there's a chance that it could damage the battery or it may indicate that it is in some failure mode already.

14+ is very typical for these when not driven a lot - and I'd bet most of these see less than an hour a day. It won't damage anything because the batteries need it. Mine ran around 15.0 most of the winter, then it's settled into the 14s with warmer weather. Normal since it's a lot harder to charge a cold battery. Also - it's the last 10% or so that's hardest to get into a battery - so drive the thing 45 minutes one way - you may get it to 90%, then the parasitic loads of the Jeep draw it back down, you drive it again - and get it back up to around 90% or so, then it sits over night, and it's back down a bit again.
Both of my JTs, the 20 and 22, it took over an hour of driving to get the system to drop into the 13s on a warm/moderate day.

My guess is that anyone seeing 14s most of the time, if they shut it off and go back 8 hours later with a volt meter on the battery posts, they'll see 12.6 or less - likely 12.5-12.4 volts. That's roughly 60% charge.

I think I'd go have that checked out by a Jeep Service center (not Firestone). It shouldn't be always up at 14V.

It will be if it's not driven daily - and the drives aren't long drives.
But the worse batteries get, the harder it is to charge them.

I always start out - before guessing or wondering, by charging each battery by itself, disconnected, and resetting the IBS and go from there.
Mine has been in the 14s since last fall - and only recently started seeing 13s when warmer weather settled in and I started driving it more. Charging the batteries also reduced running voltage as the system saw batteries with a higher state of charge (and warmer temps)
Even legacy systems from the 60s through 90s increased charging voltage by a good half volt or so in cooler temperatures.

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[jav_eee]

It is going to depend in the driving you do - or don't do.
If you never drive more than 30 minutes a day one way, or if it sits every other day, you'll never get the batteries to 100% and yeah, you'll see 14 volts most of the time.
When the batteries are FULLY charged, 100% SoC and the engine is under load, it can drop back to 12.6 for example, then up again to around 13 when you go down a hill and let off.
But if it's staying at 14+ all the time, then they are never fully charged.

it’s 14 volts whether I’m making a short trip in town or have the jeep on for 3 or 4 hours straight with a trip to the ranch or the beach (both involve hour-long one-way highway/high RPMs). I’ve had the jeep for almost 3 months now and it’s done this since day 1 of ownership. I wonder if the previous owner did any electrical mods to it because I thought it’s supposed to honk if I get off the running vehicle with the fob but it doesn’t. I have a tazer and have made sure it’s not set to disable the 3 honks.

 

[ShadowsPapa]

Thank you for that feedback. I did not charge them before installing. I wasn’t aware that was a thing. Is it possible to do so now that they are in the vehicle? Would rather not have to dig that aux battery out again. Can it be isolated and charged in place? If necessary I will do what I have to do. Any recommendations on a “good” charger.

Yup - just take the two ground cables apart and you can charge the aux battery by itself and the main battery by itself. Remove the IBS to reset it, erase all history.

You can charge the aux battery in place by connecting to the main battery positive and to the black cable that goes down to the aux battery.
Then charge the main battery the normal way.

Once it's all back together, do any subsequent charging by connecting to the cables on the top of the IBS - never directly on the main battery negative post.

Since you have a 2020 (they changed cables in 2021 model year) you can connect like this to charge aux only ->

 

[ShadowsPapa]

it’s 14 volts whether I’m making a short trip in town or have the jeep on for 3 or 4 hours straight with a trip to the ranch or the beach (both involve hour-long one-way highway/high RPMs). I’ve had the jeep for almost 3 months now and it’s done this since day 1 of ownership. I wonder if the previous owner did any electrical mods to it because I thought it’s supposed to honk if I get off the running vehicle with the fob but it doesn’t. I have a tazer and have made sure it’s not set to disable the 3 honks.

As far as I've been able to determine, the tazer is the only way to disable the honks.

I'd put a volt meter across the battery terminals when it's sitting - after a couple of hours, not running.
Could be battery going south, could also be the IBS needs to be reset. If they monkeyed with it and didn't follow procedures, who the heck knows what they did.
I always start with a known state - charging both batteries, resetting the IBS and going from there.
Everything is just a guess otherwise. Did they charge the batteries directly on the negative post or though the IBS? If directly, then it's "all screwed up" as far as what the IBS thinks the battery history is.

 

[smlobx]

OK I’ll ask…

What is the IBS and how do you reset it? Inquiring minds want to know!

 

[JTmac]

ShadowsPapa - Thank you for the picture and explanation of charging the aux battery in place. It's very helpful.

To be clear, when you say "Then charge the main battery the normal way," do I disconnect everything from the main battery (including the Intelligent Battery Sensor, aka IBS) and hook directly to the posts? I assume doing this would reset the IBS by it being disconnected during the charging period.

FWW - It would be great if they could make a sticky thread of these procedures (changing the batteries and charging them) and have them at the top of the battery talk section. I am seeing now you have explained a lot of this on multiple occasions that I did not come across in initial review of this topic area.

 

[jav_eee]

As far as I've been able to determine, the tazer is the only way to disable the honks.

I'd put a volt meter across the battery terminals when it's sitting - after a couple of hours, not running.
Could be battery going south, could also be the IBS needs to be reset. If they monkeyed with it and didn't follow procedures, who the heck knows what they did.
I always start with a known state - charging both batteries, resetting the IBS and going from there.
Everything is just a guess otherwise. Did they charge the batteries directly on the negative post or though the IBS? If directly, then it's "all screwed up" as far as what the IBS thinks the battery history is.

12.39 after sitting 17 hours.

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