Aux Battery VS Alternator VS Other issues

[ltlldft]

Jeep Wave to ya’ll.

I have been having a charging issue and no clue what is going on. My 2019 JLU “Eve” has never given me an issue, I went to start it 2 weeks ago and it was dead, nothing, no go, not today. So hubby put it on the charger and we took the truck. Charged up the battery did some research and thought oh well I guess I need a new Aux Battery and it took out my main too. ***I bypassed the auto start/stop within 1 month of purchasing “Eve”*** I called my local jeep dudes to order me an aux battery and made an appt to swap it out. I tried the work around, removing the aux negative and F42, didn’t work even with full charge. Once it was charged up it was good 13.5 ish when driving. Took the grandkids ice fishing and started it a couple different times during the 3 days to keep a charge. Noticed when going home battery/charging was down in the 12’s while on the high way. Had some things to do when I got back so left it running while finishing some work things. Driving home it was down in the 11’s.

Now I am no mechanic by any means but a gear head to a degree, used to drag race a diesel truck. My understanding has always been that if there is no charging when driving then the alternator is suspect.

When I went in to get the Aux Battery changed I made this known that I believe it is the alternator. They checked the batteries and both were fine, I had it charging over night the night before. We both discussed and started the search for a new alternator. (I cannot believe there are no AM alternator options out there yet for the JL’s) Sorry that was a squirrel moment. So stealership it is. Wow 5 days out for a new OEM one. Okay time to see if there is a local rebuilder to take a look at it. Found one and he bench tested saying nothing wrong with it. Put it back in and it sat at 14.2-14.5 for 3 days. Took it to the stealership to get it diagnosed because the next step would usually be a solenoid, no?

Knowing everything is computerized now that is why attempting diagnosis. There was a hard code about the low voltage when it would not start but that was all, nothing found. That was yesterday, today I left garage 14.3 was driving around it was good stopped and started twice and the drop started. Under fuel drops to 13.1 foot out comes back up to 13.5 ish.



Anyone have any thoughts because I am completely out of ideas. I do not want to get stranded anywhere if I can avoid it, I am getting too old for that crap.

TYFYTOTM

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[Htfan]

Where do I start?

The two "dissimilar" battery design with ESS is a headache for most people. There are literally 100s of posts on this subject just on this forum alone. Searching this forum you'll find abundant information to help your understanding from people far more knowledgeable than myself.

I'm not going into all the details because the post would get too long and all the information is available on this forum already.

1) If either one of your batteries was at or below 12v for very long, I would not trust them again.

2) the variable smart alternator on the JL will show dash voltage all over the place during a drive depending on gas pedal engagement, braking, coasting or stopped at a light with ESS engaged or not. It's mostly showing charging voltage, unless you're stopped with ESS then it will display battery voltage. The only way to really know battery health is disconnect/separate the batteries and load test individually. Voltage reading alone is not enough.

3) replacing or removing the aux battery is a simple 15 minute job going through the passenger fender. The only thing you need in addition is some extra plastic fender clips, because clip brakeage is a normal thing.

4) the JL batteries need to be replaced as a pair because they are always connected together except during a start stop event. This is why so many choose to run a single battery and disable ESS to simplify the process and remove some of the complexity. Because the batteries are "mostly" connected together if one is weak it will drain the other.

There is so much more but that's a start.

 

[Htfan]

Jeep Wave to ya’ll.

I have been having a charging issue and no clue what is going on. My 2019 JLU “Eve” has never given me an issue, I went to start it 2 weeks ago and it was dead, nothing, no go, not today. So hubby put it on the charger and we took the truck. Charged up the battery did some research and thought oh well I guess I need a new Aux Battery and it took out my main too. ***I bypassed the auto start/stop within 1 month of purchasing “Eve”*** I called my local jeep dudes to order me an aux battery and made an appt to swap it out. I tried the work around, removing the aux negative and F42, didn’t work even with full charge. Once it was charged up it was good 13.5 ish when driving. Took the grandkids ice fishing and started it a couple different times during the 3 days to keep a charge. Noticed when going home battery/charging was down in the 12’s while on the high way. Had some things to do when I got back so left it running while finishing some work things. Driving home it was down in the 11’s.

Now I am no mechanic by any means but a gear head to a degree, used to drag race a diesel truck. My understanding has always been that if there is no charging when driving then the alternator is suspect.

When I went in to get the Aux Battery changed I made this known that I believe it is the alternator. They checked the batteries and both were fine, I had it charging over night the night before. We both discussed and started the search for a new alternator. (I cannot believe there are no AM alternator options out there yet for the JL’s) Sorry that was a squirrel moment. So stealership it is. Wow 5 days out for a new OEM one. Okay time to see if there is a local rebuilder to take a look at it. Found one and he bench tested saying nothing wrong with it. Put it back in and it sat at 14.2-14.5 for 3 days. Took it to the stealership to get it diagnosed because the next step would usually be a solenoid, no?

Knowing everything is computerized now that is why attempting diagnosis. There was a hard code about the low voltage when it would not start but that was all, nothing found. That was yesterday, today I left garage 14.3 was driving around it was good stopped and started twice and the drop started. Under fuel drops to 13.1 foot out comes back up to 13.5 ish.



Anyone have any thoughts because I am completely out of ideas. I do not want to get stranded anywhere if I can avoid it, I am getting too old for that crap.

TYFYTOTM

Did you make any progress?

 

[ltlldft]

Did you make any progress?

No sorry, I had to work so was in my truck.

I believe there was a misunderstanding in my original post. Both batteries were taken out and tested and were good so the new batteries did not go in. Hence me trying to look at the alternator as the culprit. I have to go out later today so I will see where it has gone for holding a charge over 4 days.

I had read many threads on the forum however, none of them seemed to address if there was something I may be overlooking. I know that the technology between my Ram and my Jeep is different being one is a 1 ton diesel and well you know about my jeep.

I do realize that it is best to replace both together and that was what my first step was addressing but they tested fine.

I also attempted to go around the aux and it would not start with F42 out and the ground pulled off. Obviously I did something wrong.

Thank you for the information, I just have not had a chance to even get to the garage.

 

[JT1]

No sorry, I had to work so was in my truck.

I believe there was a misunderstanding in my original post. Both batteries were taken out and tested and were good so the new batteries did not go in. Hence me trying to look at the alternator as the culprit. I have to go out later today so I will see where it has gone for holding a charge over 4 days.

I had read many threads on the forum however, none of them seemed to address if there was something I may be overlooking. I know that the technology between my Ram and my Jeep is different being one is a 1 ton diesel and well you know about my jeep.

I do realize that it is best to replace both together and that was what my first step was addressing but they tested fine.

I also attempted to go around the aux and it would not start with F42 out and the ground pulled off. Obviously I did something wrong.

Thank you for the information, I just have not had a chance to even get to the garage.

There was a change to the connection of the ground on the aux to the main sometime in 20 or 21. Make sure you didn't pull the wrong ground.

The sure fire way of fixing it is ripping out the aux completely and isolating both ends of the pos and neg.

You may also need to reset the IBS. It's the little plug on the ground terminal.
https://www.jlwranglerforums.com/forum/threads/ibs-clear-reset.67955/

 

[ltlldft]

So after sitting ignored for a couple of days I went out, tip started and ran the whole time I was out above 14. I am totally confused now.

 

[ltlldft]

I have no idea what the problem was. I have had no issues at all since that problem. I am at a loss. Nothing has changed and I have left it sitting for 2-3 days untouched.

 

[DaltonGang]

I have no idea what the problem was. I have had no issues at all since that problem. I am at a loss. Nothing has changed and I have left it sitting for 2-3 days untouched.

Chalk it up to "A Jeep Thang".

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