Aux Battery Delete - Need Help!

[JeepWhealen]

The day has finally come: my battery died after less than 2 years of ownership. Now, I’m fully aware of the aux battery (AKA the parasitic battery) issue, and have researched the topic thoroughly, but I still have a few questions.

The way I see it I have a few options: replace the aux battery. Aux battery delete by removing battery, taping the wires, and pulling fuse 42. Buy a tazer/mini and turn off ESS. Buy an ESS bypass cable.

Questions:
If I delete the aux battery, do I have to feed the aux ground up to the main battery and connect it? Which cables do I need to tape and which do I need to connect to the main battery? Keep in mind I have a MY23, and I’ve seen conflicting reports that my MY has different cables.
If I buy a tazer/mini/ESS bypass cable, do I still have to replace the aux battery? Will the parasitic battery drain the main battery with these tools on?

Appreciate any insight into my questions. I’m trying to figure out the best option before I start down this path. I have upgraded the main battery with an H7 and I don’t want the parasitic battery to deplete the new battery in any way.

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[2018JLUsed]

I just did this last month on my wifes 2018JLU. My Mopar battery was an H6 with 650cca. I put in an H7 with 850cca. I left the AUX battery in place. I disconnected its negative cable at the main battery’s attachment point. I taped it up well with electrical tape and moved it out of the way. I removed fuse 42 and called it a day. At some point I may remove/replace the AUX batter, using the passenger fender access point.

I don’t have a device for deactivating the ASS. I just told my wife to hit the button each time she starts it up, it’s her vehicle after all.

 

[JeepWhealen]

I just did this last month on my wifes 2018JLU. My Mopar battery was an H6 with 650cca. I put in an H7 with 850cca. I left the AUX battery in place. I disconnected its negative cable at the main battery’s attachment point. I taped it up well with electrical tape and moved it out of the way. I removed fuse 42 and called it a day. At some point I may remove/replace the AUX batter, using the passenger fender access point.

I don’t have a device for deactivating the ASS. I just told my wife to hit the button each time she starts it up, it’s her vehicle after all.

Do you (she) get any error lights, CEL’s, or anything?

 

[Bill_P]

Pulling F42 turns off the warning light. You shouldn't get any errors after you do the delete. I did it on my wife's '18 almost 2 years ago and haven't had any issues.

 

[2018JLUsed]

No error lights.

 

[Centurion07]

Shouldn't need to pull a fuse. Just tape the aux ground, route the power to the main battery, toss the aux battery. And buy a tazer. Lots more benefits than ESS.

 

[AndySpill]

The day has finally come: my battery died after less than 2 years of ownership. Now, I’m fully aware of the aux battery (AKA the parasitic battery) issue, and have researched the topic thoroughly, but I still have a few questions.

The way I see it I have a few options: replace the aux battery. Aux battery delete by removing battery, taping the wires, and pulling fuse 42. Buy a tazer/mini and turn off ESS. Buy an ESS bypass cable.

Questions:
If I delete the aux battery, do I have to feed the aux ground up to the main battery and connect it? Which cables do I need to tape and which do I need to connect to the main battery? Keep in mind I have a MY23, and I’ve seen conflicting reports that my MY has different cables.
If I buy a tazer/mini/ESS bypass cable, do I still have to replace the aux battery? Will the parasitic battery drain the main battery with these tools on?

Appreciate any insight into my questions. I’m trying to figure out the best option before I start down this path. I have upgraded the main battery with an H7 and I don’t want the parasitic battery to deplete the new battery in any way.

I disagree with @Centurion07. If you don't pull Fuse 42 you will permit the Power Control Relay (PCR) to have the electrical current to disconnect the two batteries and isolate the Aux battery, as normally happens with dual AGM battery JLs just before the engine cold cranks. In your case no Aux battery should be found and the crank will fail. Subsequent attempts to crank your 2023 should happen solely against the main battery and the ESS off light will appear in the dash.

In a way, this gets your ESS system to turn off, but people more knowledgeable than me think it better to disable ESS thru pressing the button or aftermarket tech, and pulling Fuse 42 so that this test of the Aux battery will actually, no wiser to the vehicle, happen against the main battery instead. This is because the PCR, with no current...care of the Fuse 42 pull, can't separate the Aux battery, so all calls for Aux battery current go to all batteries, of which you will only have the main connected.

It's been explained to me that the ESS off light in the dash, not to be confused with the ESS button, when illuminated, can be a precursor that indicates problems: problems we might not see if the light is always on via just a cable pull and no Fuse 42 pull.

If you delete the Aux its ground cable, originally connected to the main battery negative post should be removed from this post and insulated. So not only don't you have to feed the Aux ground up to the main battery and connect it, it would be wrong to do so if you are taking the Aux battery out of the electrical schematic of the vehicle.

You need connect NO cables to the main battery, you simply remove one, along with the Fuse 42 pull. Two factory cables connect to the main battery's negative post. One of those cables has as its other end the body ground on the passenger's front quarter panel. Leave that cable connected at both ends. The other cable has as its distal end, even though you can't see it, the Aux battery's negative post. It is that cable whose distal end to the Aux battery negative post that you yank from the main battery's negative post and insulate/isolate.

The way I describe the procedure, by design, accounts for some factory cable swaps that occurred between years on the two factory cables that connect to the main battery's negative post. I wrote generically enough above for all model year dual AGM battery JLs.

When you say a "tazer/mini/ESS bypass cable" this to me means any aftermarket tech that turns the ESS system off for you. Use or no use of this tech, and the presence of absence of an Aux battery are two independent events. Many people use this tech to prevent the ESS system from engaging, some with Aux batteries connected, some without.

If you effect this cable and Fuse 42 pull I recommend that you make sure that ESS events don't engage. Whether that's pressing the button or acquiring this tech to do it for you I will leave up to you. Allowing ESS events to occur with the cable and Fuse 42 pull has the ESS events run off the main battery, which could rob the battery of cranking power at the end of the ESS event: ESS events are normally energized from the factory by the Aux battery, preserving the main battery for the post ESS event crank.

Sure, tons of vehicles run ESS systems with one battery. But Stellantis did not design their system this way.

The JL Tazer from Z Automotive, and the smart stop start device are not known to drain the battery. Many other smart start stop device knockoff work fine too, I just can't vouch for them, and some forum members have reported problems with some of them.

I hope this answers all the questions you posed in your OP.

 

[Centurion07]

I disagree with @Centurion07. If you don't pull Fuse 42 you will permit the Power Control Relay (PCR) to have the electrical current to disconnect the two batteries and isolate the Aux battery, as normally happens with dual AGM battery JLs just before the engine cold cranks. In your case no Aux battery should be found and the crank will fail. Subsequent attempts to crank your 2023 should happen solely against the main battery and the ESS off light will appear in the dash.

In a way, this gets your ESS system to turn off, but people more knowledgeable than me think it better to disable ESS thru pressing the button or aftermarket tech, and pulling Fuse 42 so that this test of the Aux battery will actually, no wiser to the vehicle, happen against the main battery instead. This is because the PCR, with no current...care of the Fuse 42 pull, can't separate the Aux battery, so all calls for Aux battery current go to all batteries, of which you will only have the main connected.

It's been explained to me that the ESS off light in the dash, not to be confused with the ESS button, when illuminated, can be a precursor that indicates problems: problems we might not see if the light is always on via just a cable pull and no Fuse 42 pull.

If you delete the Aux its ground cable, originally connected to the main battery negative post should be removed from this post and insulated. So not only don't you have to feed the Aux ground up to the main battery and connect it, it would be wrong to do so if you are taking the Aux battery out of the electrical schematic of the vehicle.

You need connect NO cables to the main battery, you simply remove one, along with the Fuse 42 pull. Two factory cables connect to the main battery's negative post. One of those cables has as its other end the body ground on the passenger's front quarter panel. Leave that cable connected at both ends. The other cable has as its distal end, even though you can't see it, the Aux battery's negative post. It is that cable whose distal end to the Aux battery negative post that you yank from the main battery's negative post and insulate/isolate.

The way I describe the procedure, by design, accounts for some factory cable swaps that occurred between years on the two factory cables that connect to the main battery's negative post. I wrote generically enough above for all model year dual AGM battery JLs.

When you say a "tazer/mini/ESS bypass cable" this to me means any aftermarket tech that turns the ESS system off for you. Use or no use of this tech, and the presence of absence of an Aux battery are two independent events. Many people use this tech to prevent the ESS system from engaging, some with Aux batteries connected, some without.

If you effect this cable and Fuse 42 pull I recommend that you make sure that ESS events don't engage. Whether that's pressing the button or acquiring this tech to do it for you I will leave up to you. Allowing ESS events to occur with the cable and Fuse 42 pull has the ESS events run off the main battery, which could rob the battery of cranking power at the end of the ESS event: ESS events are normally energized from the factory by the Aux battery, preserving the main battery for the post ESS event crank.

Sure, tons of vehicles run ESS systems with one battery. But Stellantis did not design their system this way.

The JL Tazer from Z Automotive, and the smart stop start device are not known to drain the battery. Many other smart start stop device knockoff work fine too, I just can't vouch for them, and some forum members have reported problems with some of them.

I hope this answers all the questions you posed in your OP.

Soooo...I'm no electrical engineer, but...

1. I've been driving mine for over 3 years with zero issues.

2. I'm pretty sure with the aux power cable routed to the main battery, the now non-existent aux battery would be really tricky to isolate.

Maybe I'm just lucky. Do what you will, and best of luck any way you choose.

 

[JeepWhealen]

Which leads me to my next question: my model JL does not have 2 cables to the negative post like I’ve seen some older models have. What cable would I be taping in this situation?

 

[THAW]

Which leads me to my next question: my model JL does not have 2 cables to the negative post like I’ve seen some older models have. What cable would I be taping in this situation?

You have an eTorque 3.6 engine, it doesn't have an AUX (ESS) battery.

 

[R3TRO]

Pulling F42 turns off the warning light. You shouldn't get any errors after you do the delete. I did it on my wife's '18 almost 2 years ago and haven't had any issues.

I pulled aux neg cable and f42. My ESS warning comes on always. Checked main battery and always sits at 12v and alternator says charging at 14.2.

Has been doing this for 3mo+ and always starts. Not sure why my ESS warning won't go off?! I mean it saves me from hitting the button, but I'm concerned the system sees a weak main battery?

 

[Centurion07]

You have an eTorque 3.6 engine, it doesn't have an AUX (ESS) battery.

Well WTF, over?

 

[JeepWhealen]

You have an eTorque 3.6 engine, it doesn't have an AUX (ESS) battery.

Wait, is this true?? How did I not know this??

 

[Old Dogger]

I just did this last month on my wifes 2018JLU. My Mopar battery was an H6 with 650cca. I put in an H7 with 850cca. I left the AUX battery in place. I disconnected its negative cable at the main battery’s attachment point. I taped it up well with electrical tape and moved it out of the way. I removed fuse 42 and called it a day. At some point I may remove/replace the AUX batter, using the passenger fender access point.

I don’t have a device for deactivating the ASS. I just told my wife to hit the button each time she starts it up, it’s her vehicle after all.

This is what I did.......

 

[AndySpill]

Soooo...I'm no electrical engineer, but...

1. I've been driving mine for over 3 years with zero issues.

2. I'm pretty sure with the aux power cable routed to the main battery, the now non-existent aux battery would be really tricky to isolate.

Maybe I'm just lucky. Do what you will, and best of luck any way you choose.

Ok. This is different from what I gleaned from your prior reply.

It sound like you have taken the cables that were connected to the Aux battery and put them on the main battery's corresponding terminals.

Yes, you have redirected all calls to isolate the Aux battery back to the main battery, which is the same effect as disconnecting the Aux battery in dual AGM battery JLs--which apparently we are learning not that the OP does not have, and pulling Fuse 42 and/or jumpering N1 to N2 in the PDC.

The OP, had he had a dual AGM battery JL, wasn't about accessing that Aux battery to get at its cables and redirect them.

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