Alternate Battery

[RooneysJeep]

2021 JL Question - My Alternate Battery died about 4 months ago, the good part is that the Stop / go engine does not work any longer , just have the annoying yellow light on my dash - My question is the dealership says I have to fix it as it will cause more damage to other items down the line , but its like $500 plus then the stop / start will turn back on again - Do I need to have it fixed ???

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[Nokones]

If you want to prevent something unexpectedly that may occur in the future that could cause you problems. You never know what could pop up when you're somewhere out in the middle of nowhere at an inconvenienced time

 

[ScotM]

You need to disconnect it so that it does not drain your main battery. There are a ton of YouTube videos explaining how to do it. It takes 5 minutes, a wrench, electrical tape snd and a zip tie. What exactly did your dealer tell you would happen if you don’t replace it?

 

[HiJinx69]

Your weak/dead auxiliary battery will eventually drain your main battery. Replace.

 

[RooneysJeep]

Thanks, they said it would drain my Primary battery , but I haev not noticed anything yet

 

[ScotM]

Thanks, they said it would drain my Primary battery , but I haev not noticed anything yet

You won’t notice it, until it won’t start. Most people just delete it by removing the aux negative cable from the main and pulling fuse 42. I added an auto stop eliminator as well.

 

[chimoab]

Either replace or properly delete it. I had the aux batter die twice on my 2019 JL. Both times the main battery ended up dead dead. Had to replace the main battery. Second time I deleted and haven't had any issues. Auto-start stop will still work off the main battery, but I have a Tazer that turns it off for me.

 

[RooneysJeep]

Either replace or properly delete it. I had the aux batter die twice on my 2019 JL. Both times the main battery ended up dead dead. Had to replace the main battery. Second time I deleted and haven't had any issues. Auto-start stop will still work off the main battery, but I have a Tazer that turns it off for me.

Thanks going to make the appointment

 

[cthomas31]

You need to disconnect it from the main and pull the fuse that connects the two batteries. Takes 5 minutes to fix and it's free. Lots of other posts about this on the forum.

 

[ScotM]

Thanks going to make the appointment

Don’t waste the $500 on replacing it.

 

[hamiamham69]

The dealer is 1 for 2. It is true that a dead or dying aux battery will eventually kill your main battery; it’s happened to me. That being said, the dealer saying not having an aux battery will cause unspecified problems down the line; that is absolutely not true.

 

[AndySpill]

2021 JL Question - My Alternate Battery died about 4 months ago, the good part is that the Stop / go engine does not work any longer , just have the annoying yellow light on my dash - My question is the dealership says I have to fix it as it will cause more damage to other items down the line , but its like $500 plus then the stop / start will turn back on again - Do I need to have it fixed ???

You've indicated the lack of ESS (engine start stop) events being a plus for you. Given that, nothing but good can come from you disconnecting the Aux battery (which you can leave in the vehicle) and pulling Fuse 42, as others have said prior, as it can, in so doing, no longer be cannibalistic to the main battery (or vice versa) as can happen when batteries (particularly of dissimilar size like here) are connected in the factory in parallel.

I would recommend that you turn ESS off in the dash, either by pressing the button or acquiring aftermarket tech to effect same. The reason I feel this way is not only because Stellantis designed ESS to work with two batteries, but paradoxically enough, the very changes you make may actually find ESS engaging. Here's why:

In dual AGM battery JLs like yours, when you attempt a crank, just prior, the ESS battery is isolated and tested for voltage to see if it has adequate power to run ESS events. With the cable and fuse pull recommended, that test will now occur, without warning or the vehicle knowing, against the main battery, tricking the vehicle into thinking it's tested an ESS battery with potentially ample power to run ESS events.

 

[BigRedRidinHood]

The Auto start stop eliminator works great if you go this route. Install it and turn off the start stop button. It then stays off. Or turn it on. It stays on. You choose what you want your Jeep to do and it remembers. Buy the best aftermarket main battery that you can and put it in the car. If your Aux battery died it may have affected you main battery. Test it but I would replace it soon. A 2021 Jeep OEM battery is probably going to be going bad sooner than later. There is nothing about having a dead battery in a Jeep that is worth waiting for this event to happen.

 

[BigRedRidinHood]

Also I am convinced that a lot of V6 engine valve train and cam problems may be a result of the ESS system in this vehicle. I don't have proof of this but I cannot help but think that shutting down a hot engine and its oiling system or a few minutes at every stop light is going to be a good thing for maintaining engine life. I have eTorque without an AUX battery by the way. Most people on this site have had no reliability issues with this system. Unfortunately Stellantis discontinued it.

 

[RooneysJeep]

Also I am convinced that a lot of V6 engine valve train and cam problems may be a result of the ESS system in this vehicle. I don't have proof of this but I cannot help but think that shutting down a hot engine and its oiling system or a few minutes at every stop light is going to be a good thing for maintaining engine life. I have eTorque without an AUX battery by the way. Most people on this site have had no reliability issues with this system. Unfortunately Stellantis discontinued it.

Thanks gonna have it fixed, was putting it off, but I agree with you that I cant leave it, thanks again

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