AUX battery delete/bypass - Which method is proper?

[bobholthaus]

My new negative bus bar, just FYI

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[Halxen]

My other idea is a big capacitor in place of the ESS battery, as the battery, during ESS events is acting as a quick discharge capacitor anyway. I wonder if that might solve a lot of the weird codes and ESS not ready issues being caused by removing the battery and #42 fuse.

Did you happen to do this idea? I'm contemplating getting the Genesis Offroad dual battery tray, replacing the main battery with a Group 25, removing the small ESS battery, rewiring the relay/ESS battery wiring "as-is" to a replacement Group 35 battery up top in the dual battery tray; thus leaving the ESS functionality "as stock" but with an equal-sized battery that is more easily serviced.

Replacing it with a capacitor, or two, is an interesting idea.

 

[DubaiMarauder]

Did you happen to do this idea? I'm contemplating getting the Genesis Offroad dual battery tray, replacing the main battery with a Group 25, removing the small ESS battery, rewiring the relay/ESS battery wiring "as-is" to a replacement Group 35 battery up top in the dual battery tray; thus leaving the ESS functionality "as stock" but with an equal-sized battery that is more easily serviced.

Replacing it with a capacitor, or two, is an interesting idea.

No, I havent tested this idea out. My JLURD is so new (Oct '23) that my ESS system is working fine, so I havent messed with it yet, but I understand electrical systems and thought it might be an interesting workaround.

 

[Go Hogs!]

The least complex method is to insulate (i.e. cover metal thoroughly with electrical tape) the terminal connectors you remove from both aux battery posts.

It's best to secure the cables against vibration/chafing.

With the aux battery removed, the aux battery ground wire does not have to be disconnected from the main battery negative post.

what is the recommended way to secure the cables inside the empty battery box? Is there something inside the box to zip tie to that would stabilize them?

 

[THAW]

what is the recommended way to secure the cables inside the empty battery box? Is there something inside the box to zip tie to that would stabilize them?

The inside of the Aux/ESS battery box doesn't really have any features to secure the wires/terminal connectors. It might be easier to secure them outside the box, but if you want to keep them in there, you could use some adhesive zip tie mounts.

Make sure the positive and negative won't come into contact with each other or any metal and won't rub on any sharp edges.

 

[Go Hogs!]

The inside of the Aux/ESS battery box doesn't really have any features to secure the wires/terminal connectors. It might be easier to secure them outside the box, but if you want to keep them in there, you could use some adhesive zip tie mounts.

Make sure the positive and negative won't come into contact with each other or any metal and won't rub on any sharp edges.

I am thinking about taping up the connectors real good with electrical tape and then put mounts on the outside of the box and zip tie the connectors on opposite sides on the outside to keep them separated. I’m not sure yet.

I still have 14 months of warranty left so at least for the time being I will hold with the bypass. I haven’t ruled out just leaving the aux sitting in the jeep bypassed.

Do you have any concerns with the main ground lug eyelet being larger than the bolt the aux negative had been sitting on with the ‘21 and up models? One positive I can think of with removing the aux is that after disconnecting the cables on the aux side I could reattach everything up top as it was intended and all connections would have the correct size bolts/lugs.

 

[THAW]

Do you have any concerns with the main ground lug eyelet being larger than the bolt the aux negative had been sitting on with the ‘21 and up models?

The terminal connector hole and stud diameter mismatch might not be ideal for electrical connections, but what matters is good, secure contact which seems to be easily achievable.

I had my Aux/ESS negative cable disconnected at the main battery for only a few months before I reattached it after removing the Aux/ESS battery, but many have had it disconnected for years without issue.

So, no, the size mismatch wouldn't concern me.

 

[Go Hogs!]

The terminal connector hole and stud diameter mismatch might not be ideal for electrical connections, but what matters is good, secure contact which seems to be easily achievable.

I had my Aux/ESS negative cable disconnected at the main battery for only a few months before I reattached it after removing the Aux/ESS battery, but many have had it disconnected for years without issue.

So, no, the size mismatch wouldn't concern me.

sorry if I missed it before but how did you secure the aux side positive and negative terminals when you removed your aux battery? Thanks very much.

 

[THAW]

sorry if I missed it before but how did you secure the aux side positive and negative terminals when you removed your aux battery? Thanks very much.

I removed my Aux/ESS battery when I installed the Genesis Dual Battery tray, so my situation might not be all that relevant to yours.

At first, I insulated the terminal connectors and doubled the cables back and zip tied them to the main battery cables. Next, I experimented with attaching the terminal connectors to the main battery's terminal connectors - worked pretty well. Currently, I'm using @DubaiMarauder's idea to attach a fuse block and bus bar to the Aux/ESS battery terminal connectors, so my cables are routed to the top of the (custom) lid on my battery tray.

 

[Lincs]

I think a new question/issue related to this
I was gone for six months and had my jeep JL 2018 on a maintenance charger and when I got back it appeared to be fully charged so I tried to start the jeep, I got the flashing lights and no start. I watched the YouTube videos and pulled the fuse and disconnected the ground and taped it off but the same issue keeps happening. It won’t start and I get flashing lights until I disconnect the positive battery cable

 

[Jebiruph]

I think a new question/issue related to this
I was gone for six months and had my jeep JL 2018 on a maintenance charger and when I got back it appeared to be fully charged so I tried to start the jeep, I got the flashing lights and no start. I watched the YouTube videos and pulled the fuse and disconnected the ground and taped it off but the same issue keeps happening. It won’t start and I get flashing lights until I disconnect the positive battery cable

Does it start with the positive battery cable disconnected? If so It sounds like your aux battery is good and your main battery is bad. Otherwise both batteries are drained.

 

[Lincs]

With the main battery positive disconnected, the cab light don’t even come on when I open the door so I’m guessing the auxiliary battery is dead?

 

[bottomland4x4]

2021 JL rubicon, 2.0 4cyl. Just replaced the h7 battery, disconnected the negative cable to aux battery and removed the fuse f42. Still says service auto start and light is on, does it have to have a jumper?
The light was on before from a dead aux battery, it only shows 10v on the aux battery.

 

[andy29847]

Having same issue after doing this bypass with the “service ESS” coming on, needed this suggestion, now going to see if it works.

The "reset' might not be immediate. Drive it a while before worrying.

 

[andy29847]

My drive to work is an hour commute one way. This is day 2, hope it resets. The only thing I’m not sure if it got the TSB software update…

I've been a strong critic of the design of the battery system in our Jeeps. My main complaint is when things start going bad, it is difficult to determine why. One of the proofs I use (for my belief) is that the other auto forums that I visit do not have sections (busy too) devoted to batteries .

Deleting the aux battery using the F42 fuse method does not change the Jeep system. The stop/start should still work. If it's not working, chances are your main battery is not putting out enough voltage to satisfy the go/no go tests that a JL/JT Jeep does as it cranks up. In my experience, the systems start generating error messages when the battery gets near 12.4v (disconnect the battery, let it sit overnight, and test with a volt meter).

If the battery is good, I would take the cables and sensor off the negative post for 15 minutes, and then reconnect to try again.

All of the information I share pertains to a JL or a JT Jeep with the 3.6 engine. Other power packages have some interesting variations and I do not have experience with them.

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