Duralast Platinum H7 AGM battery issues?

[beewil]

I have a 2024 JLU Rubicon X Auto 3.6. I'm heading to Moab in June and did not want to deal with a dead stock H6 battery issue while I was out there. So I proactively switched out to the H7 Duralast Platinum H7 AGM battery. I'm still within the three year warranty of my Jeep so I have not disconnected the auxiliary battery.(I know you can, I just chose not to) I work from home and drive my Jeep about 150 miles a week and have kept the previous stock battery on a Battery Tender 750mA while in the garage during 5-6months of cold temps in snow country. It was working well at keeping the Main stock H6 battery and Aux topped off/maintained.

Here were my issues I noticed after I had the H7 battery installed at a shop that was doing some Diff cover and Diff slider install for me.
This was a simple round trip to the post office (8 miles) and before I removed the battery tender (easy with pigtail extension), the light was green on the Tender.

1. Checked the Battery voltage before I started the car and it was 13.0. Typically with my stock battery it is around 13.8 before starting. Why?
2 I checked the battery voltage as I was driving and it showed 13.0V. Typically with the H6 stock battery I would see 13.5V. Why?
3. Driving to the post office, 8 miles round trip I had the battery display on and it dropped to 12.9V half way through the trip. Why?
4. Attached my Battery Tender 750mA to my pigtail. Battery Tender showed red light like it was charging when I returned from my 8 mile errand. And an hour later I still show a red light. The light was green when I left for my errand. Typically with my H6 stock battery that showed green before I made a similar trip, the green would come up again right after I parked it in the garage and connected the pig tail. Why is it taking so long to get the green light on the Tender when I only mad a 8 mile round trip? Also, I checked the battery while on the tender and the display said, 12.6V.
Signed,
"Electrically challenged"
Co-Signed
"Electrical stuff gives me a headache"

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[Heimkehr]

Paging @THAW

I will comment on #1. Typically, when measured while the engine is cold, the resting voltage of a healthy 12V automotive battery shouldn't be less than 12.5V. Can you confirm how long, or not, your Jeep was dormant before you measured the 13.0V that you mention? that will provide the required context here. Said differently, a resting voltage of 13.0V strongly suggests that the vehicle was driven recently, such that the resting voltage hasn't yet settled down.

 

[azjl#3]

You now have a much larger capacity battery, if the computer sees a voltage within charged range, it wont hit it with as much voltage, improves your gas mileage 0.00001 mpg

 

[beewil]

Paging @THAW

I will comment on #1. Typically, when measured while the engine is cold, the resting voltage of a healthy 12V automotive battery shouldn't be less than 12.5V. Can you confirm how long, or not, your Jeep was dormant before you measured the 13.0V that you mention? that will provide the required context here. Said differently, a resting voltage of 13.0V strongly suggests that the vehicle was driven recently, such that the resting voltage hasn't yet settled down.

I was out of the state the last five days and my new H7 was on my tender the whole time. The Tender was green before I started it this morning (indicating full charge). I thought it was odd that it was only at 13.0. Nobody drove it. I just went out to my garage and checked my Battery Tender after 3 hrs and it is still showing red. I turned on the Jeep and it said 12.9, then 12.8, then 12.6 with in about 60 seconds. That has never happened before with my H6 stock battery. I only went 8 miles. I checked my dash cam and it was off. I thought that it was draining the battery.

 

[beewil]

You now have a much larger capacity battery, if the computer sees a voltage within charged range, it wont hit it with as much voltage, improves your gas mileage 0.00001 mpg

thanks, So are you saying I should not worry about questions 1-3 I had?
Though how does that affect the question #4 (below)

4. Attached my Battery Tender 750mA to my pigtail. Battery Tender showed red light like it was charging when I returned from my 8 mile errand. And an hour later I still show a red light. The light was green when I left for my errand. Typically with my H6 stock battery that showed green before I made a similar trip, the green would come up again right after I parked it in the garage and connected the pig tail. Why is it taking so long to get the green light on the Tender when I only mad a 8 mile round trip? Also, I checked the battery while on the tender and the display said, 12.6V.

 

[Heimkehr]

I was out of the state the last five days and my new H7 was on my tender the whole time. The Tender was green before I started it this morning (indicating full charge). I thought it was odd that it was only at 13.0. Nobody drove it. I just went out to my garage and checked my Battery Tender after 3 hrs and it is still showing red. I turned on the Jeep and it said 12.9, then 12.8, then 12.6 with in about 60 seconds. That has never happened before with my H6 stock battery.

A 750mA smart battery maintainer is sized and best suited for motorcycle and OPE batteries with comparatively modest charging requirements. That's possibly why the LED light on your little Battery Tender is showing status-of-charging colors (e.g., steady red) that you're not expecting to see, particularly after it's been connected for a while. It's being asked to do more than its design brief intends.

I speak from experience, as I own two such Battery Tenders myself. They keep my bike and mower batteries fresh for the Spring.

If you want to pair an appropriately-sized maintainer to the H7 AGM in your Jeep, consider something with a minimum rating of 10 amps. Example.

 

[roaniecowpony]

I had about the same scenario going on for the past month. I first noticed it on a trip to Moab (must be the black hole of charging systems). The first thing that happened was my fridge quit working while in Moab. I was thinking the fridge had some kind of issue like a leak in the refrigerant.
It wasn't until a few days later, when we were driving down 191 toward Monticello that I noticed the dash gauge read 12.6v that I had a clue what was going on. The fridge has a low voltage shut-off threshold. So, I knew right then that fridge was fine and it was the charging system in the jeep.

So, when I got back, I check and the batteries had 12.4v. That's like 60% of full capacity. I charged the batteries and started looking into why it would charge at such a low voltage. Others have had bad Intelligent Battery Sensors (IBS). So, I bought one and changed it out. No luck.

Then I read in my service manual that the Electronic Voltage Regulator (EVR) was in the PCM. However, the IBS signal goes to the BCM where some charging logic is applied and the resulting signal is sent to the PCM, where it applies additional charging logic which controls the EVR.

I had recently changed the PCM with a salvage yard acquired PCM that we unlocked and altered the radiator fan schedule. I still have my OEM PCM and simply replaced it and drove it for a few days to confirm it's charging at appropriate voltage range (14.3 to 13.8 ish, depending on the battery drain/state of charge).

I can't tell you for certain that's your problem and a PCM is expensive to replace with programming needed etc. So, replacing the IBS is much cheaper and was someone else's solution on this forum. Order it online and you can find them for about $70. The dealers mark them up above MSRP so you can pay as much as $130 from them for an IBS.

 

[beewil]

A 750mA smart battery maintainer is sized and best suited for motorcycle and OPE batteries with comparatively modest charging requirements. That's possibly why the LED light on your little Battery Tender is showing status-of-charging colors (e.g., steady red) that you're not expecting to see, particularly after it's been connected for a while. It's being asked to do more than its design brief intends.

I speak from experience, as I own two such Battery Tenders myself. They keep my bike and mower batteries fresh for the Spring.

If you want to pair an appropriately-sized maintainer to the H7 AGM in your Jeep, consider something with a minimum rating of 10 amps. Example.

Will I need to purchase an additional pigtail with this or can I use my current Battery Tender pig tail? Or should I just get this 10amp one from Battery Tender on amazon and use my current pig tail? Thanks for the help
https://www.batterytender.com/products/10amp-batterycharger

also, there is a thread where I was told it does make a difference where the pigtail is attached to the battery post. Is that true? It was suggested to got to numbers 4 and 7. I did notice that when they installed my battery, they did not set it up this way. I had the pigtail set up that way (4 and 7) before they changed it with the new battery.

below is pic of suggested 4 and 7.

 

[beewil]

Will I need to purchase an additional pigtail with this or can I use my current Battery Tender pig tail? Or should I just get this 10amp one from Battery Tender on amazon and use my current pig tail? Thanks for the help
https://www.batterytender.com/products/10amp-batterycharger

also, there is a thread where I was told it does make a difference where the pigtail is attached to the battery post. Is that true? It was suggested to got to numbers 4 and 7. I did notice that when they installed my battery, they did not set it up this way. I had the pigtail set up that way (4 and 7) before they changed it with the new battery.

below is pic of suggested 4 and 7.

my current battery set up with H7 and pigtail

 

[beewil]

A 750mA smart battery maintainer is sized and best suited for motorcycle and OPE batteries with comparatively modest charging requirements. That's possibly why the LED light on your little Battery Tender is showing status-of-charging colors (e.g., steady red) that you're not expecting to see, particularly after it's been connected for a while. It's being asked to do more than its design brief intends.

I speak from experience, as I own two such Battery Tenders myself. They keep my bike and mower batteries fresh for the Spring.

If you want to pair an appropriately-sized maintainer to the H7 AGM in your Jeep, consider something with a minimum rating of 10 amps. Example.

the post/thread below talking about the way to connect the pigtail so you don't bypass the IBS and other big words I don't understand.
https://www.jlwranglerforums.com/forum/threads/battery-maintainer-question.87013/post-1814538

 

[roaniecowpony]

the post/thread below talking about the way to connect the pigtail so you don't bypass the IBS and other big words I don't understand.
https://www.jlwranglerforums.com/forum/threads/battery-maintainer-question.87013/post-1814538

While having a pre-wired charger connector is handy, it's not addressing your issue of inadequate charging voltage. The issue you may run into on a multi-day trip, is eventually, you may run into such a low charge that you either can't start the jeep or your fridge (if you have one) won't run due to low voltage. At low enough voltage, the vehicle will light up the dash like a Christmas tree and go into limp mode. So, getting the charging system fixed is a good idea.

 

[yokramer]

Are we sure the aux battery isnt killing the main and causing all his issues still?

 

[roaniecowpony]

Are we sure the aux battery isnt killing the main and causing all his issues still?

Didn't he say it was only showing 12.6v on his gauge? That would indicate a low (inadequate) charging voltage.

 

[beewil]

Are we sure the aux battery isnt killing the main and causing all his issues still?

Aux battery and H6 were fully charged before I added the H7. I don't think the Battery Tender shows a "green light" charged if the aux is depleted. I'm still wondering if it is where I have my pigtails connected to the battery. That is the only thing that is different from the last install, and of course the bigger H7 battery.

 

[beewil]

Didn't he say it was only showing 12.6v on his gauge? That would indicate a low (inadequate) charging voltage.

Aux battery and H6 were fully charged before I added the H7. I don't think the Battery Tender shows a "green light" charged if the aux is depleted. I'm still wondering if it is where I have my pigtails connected to the battery. That is the only thing that is different from the last install, and of course the bigger H7 battery.

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