Jumperless Aux Battery Bypass

[tsaimh]

Hello all, my ESS was not working as my dash was saying battery charging which led me to believe my aux battery was about to go. I took it upon myself to implement the bypass on this thread. Everything works as it should although now my dash says “battery protection mode”. No dash lights or anything and I have a tazer keeping my ESS deactivated. Does anyone else get this message? Should I be replacing both batteries at this point or is this normal?

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[Rhinebeck01]

Hello all, my ESS was not working as my dash was saying battery charging which led me to believe my aux battery was about to go. I took it upon myself to implement the bypass on this thread. Everything works as it should although now my dash says “battery protection mode”. No dash lights or anything and I have a tazer keeping my ESS deactivated. Does anyone else get this message? Should I be replacing both batteries at this point or is this normal?

@tsaimh

Assuming you pulled fuse F42 and you disconnected the correct cable (ESS Neg) on the Main battery negative terminal......

If you did this on your dual battery system , JL, you undoubtedly have an issue with the Main battery.

Remember, with this bypass you did, you only have the Main, 12v battery in play and no Aux battery in play. You now are running a single battery system.

Replace the Main battery and you should see that message go away.. Leave the Aux battery alone as it is bypassed, thanks to your actions.
https://www.jlwranglerforums.com/forum/threads/??-main-battery-replacement-talk-jl-jt.100534/

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Note: IF you have a decent battery/tender maintainer that plays well with AGM batteries, you could attach the tender maintainer to your Main battery and wait until the tender says the Main is charged up. Now, see if the battery protection mode message is history. It could just be your Main battery is depleted enough to trigger the message.

If the Main battery on your 2019 JL, is the factory install battery then consider it aged out and replace it!

 

[chicknwaffles]

wow there are some ingenious ways to get around the factory system.

I personally do not like the fact these have two batteries. just overly complicated.

While i'd love to convert it to one battery and call it a day the less complicated way to do things seems to be to accept it has two batteries, and replace as necessary. preferably both at the same time should issue arise.

 

[dpike]

wow there are some ingenious ways to get around the factory system.

I personally do not like the fact these have two batteries. just overly complicated.

While i'd love to convert it to one battery and call it a day the less complicated way to do things seems to be to accept it has two batteries, and replace as necessary. preferably both at the same time should issue arise.

it's all what you consider "less complicated".

 

[eck]

wow there are some ingenious ways to get around the factory system.

I personally do not like the fact these have two batteries. just overly complicated.

While i'd love to convert it to one battery and call it a day the less complicated way to do things seems to be to accept it has two batteries, and replace as necessary. preferably both at the same time should issue arise.

It's about 10x as much work (seriously, not an exaggeration) to replace the aux battery than it is to bypass it. And then in several years when it dies you get to do it all over again.

 

[chicknwaffles]

It's about 10x as much work (seriously, not an exaggeration) to replace the aux battery than it is to bypass it. And then in several years when it dies you get to do it all over again.

no doubt. not doubt.

My main question is WHY is it there to begin with, if it is really not needed? WHY did they insist on two batteries?

 

[Leisure Freak]

no doubt. not doubt.

My main question is WHY is it there to begin with, if it is really not needed? WHY did they insist on two batteries?

Its purpose is to run your environmentals when you allow the ESS stop/start to function. If you don't use auto stop/start then you don't need the aux battery. It just adds another battery fail point that has a history of failing and dragging the main battery down with it. I have a habit of pushing the stop/start disable button on every start and after several life time experiences of battery sudden death in my cars, having one less battery to mess with in my ride is simplifying it.

 

[chicknwaffles]

Its purpose is to run your environmentals when you allow the ESS stop/start to function. If you don't use auto stop/start then you don't need the aux battery. It just adds another battery fail point that has a history of failing and dragging the main battery down with it. I have a habit of pushing the stop/start disable button on every start and after several life time experiences of battery sudden death in my cars, having one less battery to mess with in my ride is simplifying it.

great. so why does every other car with ESS not have two batteries?

 

[SpacemanMike]

Anyone try this method on a 2022 Wrangler 3.0L Diesel?

I have unfortunately discovered this problem right out the gate. Built a brand-new Wrangler Unlimited Sport 3.0L Diesel, and the first two months of owning my brand-new Jeep, I had to tow it to the dealership 2 times.

I also learned that you need to make sure the dealership replaces both batteries because they just replaced the main battery the first time, and then after having to tow it back to them dead a few weeks later, they replaced both batteries and I have been fine ever since (however, I maintain my batteries with a battery trickle charger just in case).

*Luckily, I had to deal with this battery issue from my garage instead of being stranded in the middle of nowhere*

 

[Ratbert]

Anyone try this method on a 2022 Wrangler 3.0L Diesel?

I have unfortunately discovered this problem right out the gate. Built a brand-new Wrangler Unlimited Sport 3.0L Diesel, and the first two months of owning my brand-new Jeep, I had to tow it to the dealership 2 times.

I also learned that you need to make sure the dealership replaces both batteries because they just replaced the main battery the first time, and then after having to tow it back to them dead a few weeks later, they replaced both batteries and I have been fine ever since (however, I maintain my batteries with a battery trickle charger just in case).

*Luckily, I had to deal with this battery issue from my garage instead of being stranded in the middle of nowhere*

If there's a more fundamental issue isn't the trickle charge just hiding it?

I think that I'd rather have the issue identified and resolved.

 

[SpacemanMike]

If there's a more fundamental issue isn't the trickle charge just hiding it?

I think that I'd rather have the issue identified and resolved.

What I think happened was the aux battery was dying already straight from the factory and probably killed the main battery, and since the dealership didn’t switch out both batteries the first time and just swapped out the main battery, the new main battery died with the same dying aux battery.

Then after having both batteries swapped the second time, I have been okay since, however, I would like to try this jumperless aux bypass to prevent this issue from happening in the future.

 

[Ratbert]

What I think happened was the aux battery was dying already straight from the factory and probably killed the main battery, and since the dealership didn’t switch out both batteries the first time and just swapped out the main battery, the new main battery died with the same dying aux battery.

Then after having both batteries swapped the second time, I have been okay since, however, I would like to try this jumperless aux bypass to prevent this issue from happening in the future.

If the aux was fine from the factory (I sure as F* hope they test them) then you could be masking a fundamental issue. I guess that's the gamble that you're taking.

 

[oohbeetoo]

Can someone please confirm my photo below… yellow arrow is pointing at Aux Neg? Almost looked soldered closed? Sorry for the Noob question and thank you all for all the insights on this topic.

 

[Rhinebeck01]

Can someone please confirm my photo below… yellow arrow is pointing at Aux Neg? Almost looked soldered closed? Sorry for the Noob question and thank you all for all the insights on this topic.

Aux negative is always the smaller diameter cable of the two cables attached to the Main's neg side. You got it.

 

[Jimac]

Can someone please confirm my photo below… yellow arrow is pointing at Aux Neg? Almost looked soldered closed? Sorry for the Noob question and thank you all for all the insights on this topic.

Yes E-4 smaller diameter cable.

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