Stinking, Stupid, Gladiator Rubicon Auxiliary Battery

[mmulroy]

My AUX battery lasted 5 years. I was getting the AUX / ESS warning on startup. I replaced both batteries. Went with the top down approach and took the fuse box out. It really wasn't that bad. There are some great videos on youtube.

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[MudderNuker]

Going from the top is easier than removing a heavy tire, fender liner and having to replace the plastic rivets. That is what I did a few months ago.

 

[SoK66]

The AUX in my JT Sport lasted about 3 years. The only warning sign was a day before when it took longer to crank than normal but I paid it no mind. The next day same issue in the morning on the way to a meeting. After the meeting the damn truck would not start. Luckily I had my NOCO jump starter and it was a non issue. Drove straight to the dealer and replaced under warranty. I god damn hate the AUX battery. I'm going to delete it from the Rubicon.

Watching these posts closely because I have 3 Gladiator Sports in tour Jeep service and one that’s my daily driver. Seems to make sense when there’s an issue with either one of the batteries to bite the expensive bullet and replace both.

I have one of our tour Jeeps running with the aux battery disconnected and fuse 42 pulled. There have been no issues whatsoever for the past 8 months.

 

[salvino]

I took the aux battery out and connected its positive cable to the main battery terminal. Been driving it like that for about six months. Start/stop works like normal and the only issue has been a couple of alerts saying start/stop is disabled. They go away on the next restart.

I am convinced the aux battery issue is a result of both batteries getting low, but the aux battery doesn’t recharge properly afterwards once that happens. Keeping the vehicle on a trickle charger or driving it everyday is probably the best preventative measure.

 

[Bananaman]

Eco Diesel owner here. Getting to the aux battery is different for me, but everything else should be the same. Going on 3 years with my OEM batteries. I just did the aux bypass a few months ago. My understanding is that the aux battery is only there to keep the electronics stable during an ESS event. As I have a Start Stop device installed, I never have the need for that battery.
Everything works as before.

 

[Flyboy2109]

I am sure you've seen my posts before...I removed my aux batt two years ago. I ran the aux batt cables up to the main batt. I pulled no fuses and have done no other mods related to the aux batt, but I have a manual tranny and the electric add on that remembers my selection of "off" on the ESS switch. I have had absolutely no problems as a follow up.

 

[Crazy Wes]

2023 Rubicon.. 10 months ago decided to delete the aux battery. Start stop was never available 95 percent of the time leading me to belive it was going bad. Dont like the stop start and am using a tazer to keep it off most times. Removed the aux and tied into the upper battery. Also upgraded to next larger size battery for main. Left the 42 fuse in place. 10 months in and every thing works perfectly. I use the tazer to keep the start stop turned off. The main reason for doing this was the reported problem of not being able to jump start the system if it dies with the aux battery. Less weight more dependability more battery capacity for my winch. The aux battery is the stupidest thing Jeep has ever done.

 

[DGJeep]

I was tired of the anxiety of getting stranded. I just did the Aux bypass and pulled fuse 42. No codes so far! I still have the original battery, but will probably do an upgraded H7 battery like most people suggest this summer.

 

[efitzger]

Delete that useless aux nonsense and program with tazer mini. Absolute waste of money and time to replace the aux.

 

[salvino]

2023 Rubicon.. 10 months ago decided to delete the aux battery. Start stop was never available 95 percent of the time leading me to belive it was going bad. Dont like the stop start and am using a tazer to keep it off most times. Removed the aux and tied into the upper battery. Also upgraded to next larger size battery for main. Left the 42 fuse in place. 10 months in and every thing works perfectly. I use the tazer to keep the start stop turned off. The main reason for doing this was the reported problem of not being able to jump start the system if it dies with the aux battery. Less weight more dependability more battery capacity for my winch. The aux battery is the stupidest thing Jeep has ever done.

As I posted, I deleted my aux battery a while ago as well. I neglected to mention that I upgraded to a larger main battery at that time as well. Not sure why they think they need that second battery. I’d love to know.

 

[Mr._Bill]

As I posted, I deleted my aux battery a while ago as well. I neglected to mention that I upgraded to a larger main battery at that time as well. Not sure why they think they need that second battery. I’d love to know.

The Aux Battery is there to keep the computers from rebooting due to low voltage during ESS restarts. The Main and Aux are paralleled together all the time. They are only separated for the Aux Battery Test at startup, and during ESS restarts.

This particular two battery design possibly came from Mercedes, who has been using something similar since at least 2013.

 

[Crazy Wes]

The Aux Battery is there to keep the computers from rebooting due to low voltage during ESS restarts. The Main and Aux are paralleled together all the time. They are only separated for the Aux Battery Test at startup, and during ESS restarts.

This particular two battery design possibly came from Mercedes, who has been using something similar since at least 2013.

To protect against low voltage yet it is the cause of all our battery problems.... like an oxymoron.... Dosen't mater what trade or industry ENGINEERS ARE OVER EDUCATED IDIOTS WITH NO COMON SENSE!

 

[ShadowsPapa]

Never ceases to amaze me how so many jump to the conclusion, often incorrect, that the aux battery is the cause of global warming, inflation, insurance costs, hurricanes in Florida and your Jeep's electrical issues - all without any testing (and all because "the internet said so)

I'm heading on 3 years with mine - both batteries are fine, including the aux battery. ESS works perfectly after all of this time.

Maybe it's because I keep the batteries charged even though the truck may sit for almost a week at a time?

I'll repeat this since there's still a lot of 'but the internet said so' going on:
Go look at the 4xe forums out there - not associated with these or the Wrangler forums. What's the big talk of electrical issues? the batteries failing.
No, not the big HV batteries, but the 12v batteries.
What's one of the clues? Aux switched unavailable.
Now most members here would jump and say "obviously your aux battery is failing".
Yet - there is no aux battery on a 4xe. They have only one and it's the exact same battery as our JT main battery.
Another mistake too many make is believing that the aux batter handles the aux switches or ESS or whatever.
Also incorrect.
Both batteries are connected in parallel at almost all times.
Auxiliary means just that and it's a sad coincidence that both those switches and that small battery have the word "auxiliary" in front of them. They are in no way connected to each other.

My questions are:

1. What indicators did I miss to let me know the aux. battery was failing?
2. Can this battery be load-tested somehow
3. Should I do the battery delete (remove #42 fuse, etc.) and move on
4. Would there be any long-term effect on the electrical system without the aux. battery in use
5. What is the proper way to load test the main battery?
6. How long does the aux. battery lasts under normal driving conditions (months, years)

Again - it could be EITHER battery - do not assume. I happen to be really observant and do watch voltage here and there. I watch for how long the battery voltage stays up during an ESS stop (but if you shut that down, then you can't use that as a tool)
Things that lead to short battery life - of BOTH batteries, and they are tied together 99.9999999% of the time, are infrequent drives, drives shorter than 30 minutes even if you do drive fairly frequently and so on.
Modern vehicles drain batteries down. And driving to work and back for most people isn't always enough to keep them up. So if you don't drive regularly, or do mostly short drives - a battery tender, such as "BatteryMinder" or similar is a good idea.
Why do the battery delete?
The auxiliary battery will last as long as the main battery if things are taken care of - kept charged. The chances of the main going are the same. They live connected together save for fractions of a second when the vehicle is started, then when the vehicle restarts after an ESS stop. Otherwise, they are paired together so there's really nothing that's likely to kill the "aux" battery more than the other.

OF all of the Jeeps we've owned with these systems, including Grand Cherokees and my 2 JTs, only once did we have battery failure. And then it was 35 months from new. It was my wife's Grand Cherokee at the time and it sat sometimes 1 or 2 weeks at a time (and silly me never bothered to keep a battery tender on it so really I blame myself)

Going from the top is easier than removing a heavy tire, fender liner and having to replace the plastic rivets.

You don't have to remove the tire and liner. Several here have done it. There are videos out there showing how to get to it without all of that - from the side behind the tire, not fully removing the liner.

 

[Mr._Bill]

To protect against low voltage yet it is the cause of all our battery problems.... like an oxymoron.... Dosen't mater what trade or industry ENGINEERS ARE OVER EDUCATED IDIOTS WITH NO COMON SENSE!

That statement is just wrong and ignorant on so many levels.

The biggest problem is the vehicle not being driven enough to keep the batteries charged.

The Jeep OEM batteries are not the highest quality available, but they are adequate. Jeep has had issues with batches of defective batteries. Dealers will let the vehicles sit on the lot for months with discharged batteries, which leads to early failure. It is a major inconvenience, but Jeep will replace the batteries under the 3/36 warranty when they do actually fail.

 

[Crazy Wes]

That statement is just wrong and ignorant on so many levels.

The biggest problem is the vehicle not being driven enough to keep the batteries charged.

The Jeep OEM batteries are not the highest quality available, but they are adequate. Jeep has had issues with batches of defective batteries. Dealers will let the vehicles sit on the lot for months with discharged batteries, which leads to early failure. It is a major inconvenience, but Jeep will replace the batteries under the 3/36 warranty when they do actually fail.

AND.... I'M FROM THE GOVERNMENT... I'M HERE TO HELP YOU... BWAHAHAHAHAHA. Mine is my daily driver the start stop is rarely ever working. Always says unavailable. Why put in cheap dealer batteries. I replaced with better quality and dont have to worry about dependability.

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