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Your battery voltage - truck off and at rest

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ShadowsPapa

ShadowsPapa

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This is exactly my point. Maybe there isn’t enough full voltage charge time in its factory set points.
Actually, there is.
Unless the battery SoC is at or near 100%, the voltage stays up above 14 volts. I have only ever seen those voltages in the mid 13s to upper 12s when the batteries were at 100%, cruising on the highway, no real electrical load to speak of.
Put the off-road pages up on the radio and watch the voltages - if your batteries are under 12.5 you aren't going to see system voltages under 14.

HOWEVER, I'm beginning to wonder if the batteries Jeep is using are needing voltages even HIGHER - my battery charger charges my JT batteries at higher voltages than my truck ever reaches.
And if you look at the manufacturer's recommendations for their specific batteries, some vary a bit - some suggest a max of 14.6 or 14.7 while others suggest they need 14.8 to 15.0 volts absorption phase.

These Jeep just don't seem to be aligned with charging the batteries they are using, and charging two very different sized batteries can be problematic. One will reach "full" or saturation much faster than the other will.........

My truck recently sat for a good 10 days (been sick, not driving for well over a week). I decided to spend what energy I had to check the batteries.
Still together in the stock parallel configuration, still connected to truck's systems, meaning some parasitic draw from the electronics, the combined reading was 12.19 volts.
I pulled the negative cable from the aux battery off the top of the IBS, isolating the batteries from each other. (and the AUX from the truck's electronics which was interesting because when I opened the door, everything still functioned normally)
The AUX battery by itself read 12.29
The crank battery (apparently still feeding the truck's electronics!) rear 12.26 volts
Weird - together it was just shy of 12.2, independently they were each over 12.2 and even though the negative was pulled off so the aux battery would be isolated, the crank battery still feeds the truck electronics.
(which begs the question - why will the vehicles sometimes not start? The CRANK battery still feeds the truck's electronics - the crank positive is on N2 which is directly connected to N3 through a fuse, which then feeds through the closed PCR contacts, and up to N1 - the system electronics. So if the aux battery is removed, the crank battery still feeds the truck's electronics!)

Anyway, with the negative cable from the aux battery pulled off the IBS, I charged it using my charger's 2 amp setting. It only took a couple of hours for it to reach 12.8 volts, 100% charge! And that's at the charger's lowest setting. Keep that 2 hours in mind.........

I then moved the charger's negative clamp to the top of the IBS on the crank battery and set the charger to 10 amps.
Independently, it said the battery was 40%. Interesting as when both batteries were connected together, it said they were 31% state of charge. Yet apart, the crank battery was 40%.
I let it run on the 10 amp setting. The charger went through all of the phases and didn't get through the completion phase to rest for several hours.
At 2 amps the aux battery charged in a couple of hours, through all phases, including completion and even rest.
At 10 amps, the crank battery took all day to charge - all phases, to the rest phase.
The net result - I hooked things back up, we needed some supplies (needed more food that Yawnie would eat and some OTC meds for me, etc.) and when I came to the first stop sign at 1.1 miles away, I didn't push the brake pedal hard enough to see if ESS would work or not. The next stop sign was under 1/4 mile away, so from home to the second stop sign was about 1 1/4 miles from home, and ESS worked fine. In fact, it worked the entire remainder of the morning. And the truck's voltage stuck right around 14.3 which I found really interesting considering there was little load, batteries were charged - but the AC was on so that was likely a power need. I expected it to be in the 13s.

I still believe charging 2 very different size batteries is problematic, and I'm not convinced the PCM is configured with the proper charging sequencing for the specific batteries used but I need to check my log dumps to get more information to see that the configurations are for various IBS conditions.
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Hmmm I just went outside to my JT after setting all night, battery voltage 13.1 But mine is a exception, it's got a 85 w solar system.
My LJ charges at over or at 14v and from first day I had it I got flashed due to thinking I had high beams on. Go figure after changing to aftermarket headlights that stopped. OEM halogen lights vs aftermarket.
Bottom battery charge is the starting batteries.
top battery charger is for "House" battery being charged by other solar system
Jeep Gladiator Your battery voltage - truck off and at rest Screenshot_20220601-100756_Renogy BT
 

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Bill I think you are correct with your thought on the charging system (alternator, PCM ect) I think the two batteries, age of each ect. have them "fighting" over charge, then the Jeep system reads one or overall then doesn't fully charge them. That's my uneducated though.
 

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Hmmm I just went outside to my JT after setting all night, battery voltage 13.1 But mine is a exception, it's got a 85 w solar system.
My LJ charges at over or at 14v and from first day I had it I got flashed due to thinking I had high beams on. Go figure after changing to aftermarket headlights that stopped. OEM halogen lights vs aftermarket.
Bottom battery charge is the starting batteries.
top battery charger is for "House" battery being charged by other solar system
Jeep Gladiator Your battery voltage - truck off and at rest Screenshot_20220601-100756_Renogy BT
Thanks for the solar idea. My pockets just shed a tear..
 
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[RANT MODE]
I've seen talk out there in other threads in this forum about these alternators being "smart alternators".
That seems to be confusing people into thinking or believing that these alternators are somehow different, or better, or more expensive or more complex than others.
IMO, the term is absolutely STUPID. The alternator is dumb. And if the term simply means, like several auto electric sites have historically described it, as meaning "it is controlled by an ECU or PCM and lacks an internal regulator" - if it means it's smart because it lacks an internal regulator, then alternators from the 60s and 70s were smart - there was no internal regulator.
Oh, it means it's controlled by the PCM? Then in the 1990s, Jeep was using smart alternators because they were controlled by the PCM - but the voltage was set, they were set or regulated to a set voltage of, say, 13.8 volts, for example.............
OK, so it means the PCM controls how the alternator works based on information it has gathered or that some device like an IBS sends to the PCM and determines alternator output based on a variety of factors and inputs.
How is that making the alternator smart?
It's not.
The alternator is still dumb as a box of rocks. It's still the same thing Jeep and others used in the 1990s. There is nothing special, fancy, different, or more expensive about these alternators. It's a simple basic alternator without an internal regulator. Gee, then it's like a 1963 Motorola A12NAM453.

When you hear the term "Smart Alternator" - some uneducated writer coined that phrase because they were writing for some magazine and didn't understand how charging systems worked and figured the alternator was smart or somehow different. It's actually more BASIC than the GM/Delco 12si, fewer parts than the 12si, less complicated than the 12si.
These are just like the alternators I work on almost every day.

There's nothing in these that makes them special or tricky. You can get them wet and there's nothing inside to worry about - no modules, no electronics.

This is a description from the web - an auto electric company:
Smart alternators are essentially those that have their output voltage controlled externally via the Engine Control Unit (ECU) rather than by an internal voltage regulator as found on traditional alternators.
[/RANT MODE]

The cool alternators are brushless. Even less to worry about in water or bad conditions.
 

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Thanks for the solar idea. My pockets just shed a tear..
I really understand I dis too when I got the Cascadia solar system. Then again as I started building the second one for my JT.
 

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Bill as you said coined by some writer, by that it is a smarter than that writer. :like: :like:
 

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HOWEVER, I'm beginning to wonder if the batteries Jeep is using are needing voltages even HIGHER - my battery charger charges my JT batteries at higher voltages than my truck ever reaches.
And if you look at the manufacturer's recommendations for their specific batteries, some vary a bit - some suggest a max of 14.6 or 14.7 while others suggest they need 14.8 to 15.0 volts absorption phase.
Shadow’s papa:
That is my point. AGMs need a higher voltage over a long time to fully charge.

I have been through quite a bit dealing with RV batteries...lead acid, AGM, and soon to be lithium (due to minimal recharge time and actual useable depth of discharge). Recharging an AGM usually takes a number of hours at 14.5v plus.

Also, with systems that have high parasitic losses like all new cars, they can’t be left to sit without a charger for more than a week. Weather can have an impact as well.

I’d love to see what happens to an EV if left to sit unattended for a couple weeks.
 
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Shadow’s papa:
That is my point. AGMs need a higher voltage over a long time to fully charge.

I have been through quite a bit dealing with RV batteries...lead acid, AGM, and soon to be lithium (due to minimal recharge time and actual useable depth of discharge). Recharging an AGM usually takes a number of hours at 14.5v plus.

Also, with systems that have high parasitic losses like all new cars, they can’t be left to sit without a charger for more than a week. Weather can have an impact as well.

I’d love to see what happens to an EV if left to sit unattended for a couple weeks.
And yet the authoritative sites on batteries, even the companies that make batteries, say AGM charge 5 times faster and require lower voltages to charge.

My smart charger in AGM mode charges at a lower voltage, constant current, in the "fast charge" phase, then lowers the current and ups the voltage to a bit over 14 to finish and taker to the completion phase where voltage and current is dropped.

AGM batteries are used for solar power and backup systems because they deep-cycle better - to a point..........

This from a company that makes AGM and Lithium batteries -
3. They have a short charging time.
AGM batteries, compared to flooded batteries, charge quickly. When compared to flooded batteries of a similar capacity, the charging rate can reach five times faster with the same power source.


And this from another company that makes AGM and other batteries -
Jeep Gladiator Your battery voltage - truck off and at rest 1654112870119



Most battery sites and makers say they are ideal for RV and power supplies because they can handle constant discharge much better than wet batteries - in fact, they tout them as being ideal for RVs, deep cycle situations, backup power supplies and so on.
Mine sat for at least 10 days and was actually no lower than other measurements I've taken on the batteries, looking back to my earlier posts, so sitting 10 days did them no harm.


I found this which is close to describing how my smart charger works -


If you would like to speed up your SLA charge time, you can use a charger with a more complex two-stage process. This process combines an initial constant-current bulk charging phase with a constant-voltage top-up phase.

After the discharged battery receives a reasonable charge at a level of 32.72 degrees Fahrenheit or above, it continues until the voltage reaches 2.45V per cell (i.e., 7.35V for a .6V. battery, 14.7V for a .12V. battery), where the charger then changes to constant voltage, continuing to deliver current as the remaining charge is stored.

During the second phase the charger monitors the delivering current which stabilizes in time when the battery is completely charged. The battery should be charged in 5 -6 hours using this type of charger, which is within the typical recommended manufacturer guidelines.

Some chargers of this type, typically called three mode chargers will continue to monitor the battery after it is charged, delivering a low float charge to maintain the battery at a full charge.



https://batteryuniversity.com/article/bu-201a-absorbent-glass-mat-agm
 

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Not doubting the info that you are finding (there are also alot of people who have set up testing systems for independent results for both depth and rate of discharge as well as recovery and saturation requirements. Since they don't have a sales stake in it their results are a little different). Yes, AGM will charge faster than Lead Acid. I personally use a triple mode charger for my AGMs (4-8GPL lifelines as well as 2 large 12V lead acids). Depth of useable discharge max on an AGM is still less than 50% total and the last 20% to full saturation takes the most amount of time (hence you could very easily be in a 20% range of use if not fully recharged). Lithium can go down to 20% and will only take about 2 hours to full saturation. But, I digress...

Regarding our Gladiators...old methodology worked for many years and batteries lasted for about 5 years on average. Recently, there are ALOT of Gladiators that have been loosing their batteries at two years. Dealing with multiple batteries on other systems...once one goes bad, it takes down the rest. So, maybe the big and little impact each other. Maybe the charge rate isn't quite what it needs to be. Either way, something doesn't seem right for longevity. Maybe the increased fuel mileage costs overcome the battery replacement costs at the current $6.00+/gallon fuel costs. LOL
 

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Regarding our Gladiators...old methodology worked for many years and batteries lasted for about 5 years on average. Recently, there are ALOT of Gladiators that have been loosing their batteries at two years. Dealing with multiple batteries on other systems...once one goes bad, it takes down the rest. So, maybe the big and little impact each other. Maybe the charge rate isn't quite what it needs to be. Either way, something doesn't seem right for longevity. Maybe the increased fuel mileage costs overcome the battery replacement costs at the current $6.00+/gallon fuel costs. LOL
My gut says there are a couple of things going on - charging two batteries of different capacities and sizes in parallel
and
I think their charging process needs to be revisited. The voltages just don't seem to line up right.

Yes, when one goes, depending on how it goes (they can go with an open which is similar to it not being there at all), if it goes with a short or similar issue, it's a load on the other battery just like leaving the lights on is a load. And taking the AGM down constantly and never quite fully charging it, over and over, is a death knell.
 

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After driving all day in Silverton Co I noticed my voltage gauge reading 12.5. About five seconds later it jumped to 13.6. It kept bouncing back and forth every five to six seconds ranging from 12.5, 12.6, 12.7, to 13.5, 13.6, 13.8. I put a volt meter on he battery with the engine off and got 12.5. With the engine running I got 12.9. This has never happened before with all stock electronics. Btw I have a 2020 Rubicon. The voltage gauge just popped up on my dash reading 12.5. I switched over to my off road pages and read the same. Anyone else have the same issues?

Mark
 
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12.5 seems low. I can see 12.7 or so, but to see it at 12.5 and seeing your battery is sitting only at 12.5 with the engine off feels wrong.
Driving for hours should fully charge the batteries. And fully charged should be sitting at 12.7 with everything off.
That much jumping around doesn't sound normal, either. Things will often vary from minute to minute, like 13.7 then 13.8, maybe 14.0, then down a tenth again.
These don't normally cut the voltage down into the 12s unless the battery is charged, or, it detects excess heat at the battery (charging a hot battery is bad) so that could have something do to with it.
Questions would be - how long did it sit before being driven for hours? If for several days, and if like here, it was in the 90s, it could be it detected things as being too hot.
 

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Thanks for the response Bill. I towed the truck to Silverton from Albq yesterday. I started it and moved it to my camp site, (5 min) at 2pm. Took off at 8 am and the gauge started acting up at 3 pm. Possibly the alternator going out? Night temp 40 and day temp at 70.

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Been sitting for 48 hours. 12.43 volts. It gets driven long distances regularly and never sits for more than a few days. It’s also always shown a charging voltage of 14-14.5 on the in dash screen since new (18k now) which doesn’t make me feel warm and fuzzy about the oem battery
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