Start Stop battery out again

[Dyolfknip74]

Here's the thing. Batteries aren't like a light switch that flip from "good" to "bad". They progressively lose their ability to maintain a voltage level. "Tested Good" means that it hasn't deteriorated below an arbitrary point where it's considered no longer useful. But it can be rather close to it and still be "tested good". It's guaranteed to be worse than your new battery.

That old battery will act like a vampire and suck the life out of the new battery until they are both equally bad. So if you replace one, always replace the other (in spite of it still being "good") so both batteries are always at equal levels of wear. That will maximize the lifespan of both batteries.

If you replace batteries individually, you will constantly be in a situation where one battery is stressing the other. You will go through a lot of batteries this way.

Well, to be fair, lithium batteries will go from good to bad like a light switch but that has no bearing on this conversation.

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[grimmjeeper]

What brand do you recommend. I think I am going to replace both.

A lot of brands are just different labels on batteries manufactured by just a few companies. Pretty much all of the aftermarket AGM batteries are good. Certainly better than the junk you get from the dealership.

I went with Die Hard because they were convenient to buy at a local parts store.

 

[grimmjeeper]

Those that have had the Aux Batt fail…. What are the symptoms? How do you know it’s failing? I’m just curious to know what to look for if it should start to happen to me. Thx!!

I started getting messages about aux switches not being available.

 

[TheNewGuy]

Those that have had the Aux Batt fail…. What are the symptoms? How do you know it’s failing? I’m just curious to know what to look for if it should start to happen to me. Thx!!

Constant "Start stop not available battery charging" message

 

[slowpoke387]

Mine is a 3.6 engine, 2018, both batteries amazingly enough are still good even after completely discharging them by accident like 6 times already.. I recently removed fuse 42 and disconnected the negative terminal for the ESS battery... my JL starts normal and I have no warning lights.. I have a Tazer to disable that pesky ESS... removing fuse 42 / disconnecting the ESS battery is the simplest solution

3.6's dont seem to be having this issue. 2.0 is the culprit I believe.

 

[guarnibl]

My aux battery went off like half a year ago. With that, so did my auto start/stop. Never a problem until this past Sunday. My car wouldn’t start, just took it in to my dealer today and since I bough it pre-owned , sadly the battery wasn’t under warranty. Now I have to pay $1300 to get both batteries replaced, plus the battery sensor. Sucks .

$1300? What?

Delete the aux battery and just get a stout main battery and save $1000...

 

[Fudster]

What brand do you recommend. I think I am going to replace both.

Pick a thread, any thread. Well not really. Do you have the tow package? If so go with the fourth link.

Deference to @Rhinebeck01 .


https://www.jlwranglerforums.com/forum/threads/-main-battery-replacement-talk-jl-jt.100534/

https://www.jlwranglerforums.com/fo...isconnecting-aux-battery.100296/#post-2076821

https://www.jlwranglerforums.com/fo...-in-traffic-dash-freakout.95139/#post-1973564

https://www.jlwranglerforums.com/fo...w-package-oem-replacement.76572/#post-1593118

https://www.jlwranglerforums.com/fo...t-question-for-the-experts.66343/post-1403000

 

[ConqSoft]

Dealer just replaced both my batteries no questions asked, at 25k miles. $800+ for both batteries and labor, covered by warranty.

 

[smokeythecat]

Batteries aren't like a light switch that flip from "good" to "bad". They progressively lose their ability to maintain a voltage level.

Not always true. My nearly new factory battery failed catastrophically. One of the cells went bad, possibly a short. I got it replaced under warranty, but ever since I have been leery of it. I plan to get a Genesis kit at some point not because I run a bunch of auxiliary stuff (I don't even have an aux battery now), but because I want that failover in case something goes wrong way up in the hills.

 

[Reinen]

Not always true. My nearly new factory battery failed catastrophically. One of the cells went bad, possibly a short. I got it replaced under warranty, but ever since I have been leery of it. I plan to get a Genesis kit at some point not because I run a bunch of auxiliary stuff (I don't even have an aux battery now), but because I want that failover in case something goes wrong way up in the hills.

When you're dealing with a linked two battery system, it still is true. You just had an unusual failure that preempted it. It was still progressively losing its ability to hold a charge before you had the catastrophic failure. The other battery was doing the same but did not have a catastrophic failure.

If you just replaced the battery with the catastrophic failure, the other battery would still be slightly worn and would be unable to hold the same charge level as the new battery. Unless that catastrophic failure happened early in the lifecycle of the batteries it would still be worth replacing both.

However since it was a warrantee repair it all becomes moot. The replacement battery would have a shorter lifespan because both batteries weren't replaced, but so what? It wasn't out of your pocket and its shortened lifespan would be similar to never having the catastrophic failure on the original battery.

 

[WrangleDangle]

Not that you should have to, but can you/are you willing to put your Rubi on a trickle charger when the vehicle is parked at home?

Putting such a device on the terminals of the main battery charges both batteries.

As an alternative, if you're willing to run with ESS off, we can talk about how to bypass the ESS battery all together.

I would like to know how to run without the auxiliary battery. Mine is starting to go on my 2020 Rubicon. Rather than buy a new battery for something I'd rather not have to begin with, how hard is it to disable or preferably remove from the system all together?

 

[Old Dogger]

I would like to know how to run without the auxiliary battery. Mine is starting to go on my 2020 Rubicon. Rather than buy a new battery for something I'd rather not have to begin with, how hard is it to disable or preferably remove from the system all together?

https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

 

[WrangleDangle]

https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

Thank you very much for this info.

 

[Fudster]

I would like to know how to run without the auxiliary battery. Mine is starting to go on my 2020 Rubicon. Rather than buy a new battery for something I'd rather not have to begin with, how hard is it to disable or preferably remove from the system all together?

Jeff, the link you have been given is excellent. It will take you to steps you can take to remove the ESS battery from the electric schematic of your 2020 and produce no error codes on the dash (i.e. EVIC).

But this approach, and I'm not knocking it, and its predecessor approach involving a fused jumper, has its caveats, which are covered in the link. Those caveats include you taking steps to make sure that the ESS system doesn't engage: something you can do as simply as pressing the ESS off button each time you cold crank, or buying technology like StartStopStart (less expensive, only turns off ESS) or the Z Automotive Tazer (more expensive does many things including turning off ESS) to do such switching off for you.

I can't recommend running ESS on one battery, much that it's designed that way in many other vehicles, because without the ESS battery, the energy to run appliances during an ESS event comes from the very cranking battery whose power could be robbed of ability to turn over the engine when the ESS event completes.

All this said, there is a 3rd way I've personally tested (on my 3.6L) and others have confirmed for model years 2019 and beyond (long story available on request.)

Just disconnect the negative cable on the main battery's negative post that leads back to the ESS battery like discussed in the link, but don't touch the fuse. From the factory there will be two black cables on the main battery's negative post. The one whose other end is attached to the body ground on the passenger's front fender should be left alone and connected.

With this cable disconnected attempt to crank your Rubi. Expect it to fail because no ESS battery is now connected. But try again. On second attempt, and all those thereafter your 2020 should automatically try to crank solely off the main battery. If successful it should continue to forever look only at the main battery, throwing an error code in the dash that reads "ESS off."

Some people hate seeing such codes and take the linked route which neither shows such a dash message, nor turns ESS off.

But truth be told, some people see this "error" message, in turning ESS off, as a feature, as it will save you the step of having to turn it off yourself using the methods discussed above.

It's all about what works for you. I run with ESS, but question people who get upset seeing a warning message (ESS off) that conveys the very thing they wish.

At any point that an energized ESS battery is reintroduced and connected, at the next cold crank the vehicle should revert back to recognizing two batteries, and turning the ESS off light off (i.e. allow ESS to engage if the conditions hold for it to do so.)

 

[WrangleDangle]

Jeff, the link you have been given is excellent. It will take you to steps you can take to remove the ESS battery from the electric schematic of your 2020 and produce no error codes on the dash (i.e. EVIC).

But this approach, and I'm not knocking it, and its predecessor approach involving a fused jumper, has its caveats, which are covered in the link. Those caveats include you taking steps to make sure that the ESS system doesn't engage: something you can do as simply as pressing the ESS off button each time you cold crank, or buying technology like StartStopStart (less expensive, only turns off ESS) or the Z Automotive Tazer (more expensive does many things including turning off ESS) to do such switching off for you.

I can't recommend running ESS on one battery, much that it's designed that way in many other vehicles, because without the ESS battery, the energy to run appliances during an ESS event comes from the very cranking battery whose power could be robbed of ability to turn over the engine when the ESS event completes.

All this said, there is a 3rd way I've personally tested (on my 3.6L) and others have confirmed for model years 2019 and beyond (long story available on request.)

Just disconnect the negative cable on the main battery's negative post that leads back to the ESS battery like discussed in the link, but don't touch the fuse. From the factory there will be two black cables on the main battery's negative post. The one whose other end is attached to the body ground on the passenger's front fender should be left alone and connected.

With this cable disconnected attempt to crank your Rubi. Expect it to fail because no ESS battery is now connected. But try again. On second attempt, and all those thereafter your 2020 should automatically try to crank solely off the main battery. If successful it should continue to forever look only at the main battery, throwing an error code in the dash that reads "ESS off."

Some people hate seeing such codes and take the linked route which neither shows such a dash message, nor turns ESS off.

But truth be told, some people see this "error" message, in turning ESS off, as a feature, as it will save you the step of having to turn it off yourself using the methods discussed above.

It's all about what works for you. I run with ESS, but question people who get upset seeing a warning message (ESS off) that conveys the very thing they wish.

At any point that an energized ESS battery is reintroduced and connected, at the next cold crank the vehicle should revert back to recognizing two batteries, and turning the ESS off light off (i.e. allow ESS to engage if the conditions hold for it to do so.)

Thank you so much for this info. You mention a "long story" I would appreciate a copy of it.
Thank you -
WrangleDangle

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