Jumperless Aux Battery Bypass

[Wrangler man]

@Wrangler man

Hey Howard:

When you wrote that bypassing the ESS battery will not allow you to charge the main battery when it dies, my"read" was that a dead battery won't charge well, not that the ESS bypass somehow prevents the jump starting of the remaining battery.

Is that correct?

I was fortunate enough that the Aux battery died without warning while the Jeep sat in my garage (not a daily driver). Called FCA road side because my larger battery jumper that I bought just for this diesel engine and upsized form my former jumper battery failed to do anything. This new one is capable of jumping a large 8 cylinder engines including this 3.0 diesel. So the flatbed showed up. He threw his even Bigger jumper at my dead battery into his dismay no start. So we took it to the dealer knowing it would be under full warranty for 3/36. The dealership came out with not one but two other biggest battery jumpers and once again no luck! , so a few porters pushed the Jeep back to the bay and the mechanic swapped out both batteries. I asked the service writer in the future if my battery dies what can be done to jump it? he said "he has no answer answer for me, no solution".
This is unacceptable but after doing research I came up with the solution which also eliminated some of the other wacky electronic issues I was seeing on my Dash frequently.

The following thread is exactly what I did. Hope this is helpful to you and others.


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[Fudster]

I was fortunate enough that the Aux battery died without warning while the Jeep sat in my garage (not a daily driver). Called FCA road side because my larger battery jumper that I bought just for this diesel engine and upsized form my former jumper battery failed to do anything. This new one is capable of jumping a large 8 cylinder engines including this 3.0 diesel. So the flatbed showed up. He threw his even Bigger jumper at my dead battery into his dismay no start. So we took it to the dealer knowing it would be under full warranty for 3/36. The dealership came out with not one but two other biggest battery jumpers and once again no luck! , so a few porters pushed the Jeep back to the bay and the mechanic swapped out both batteries. I asked the service writer in the future if my battery dies what can be done to jump it? he said "he has no answer answer for me, no solution".
This is unacceptable but after doing research I came up with the solution which also eliminated some of the other wacky electronic issues I was seeing on my Dash frequently.

The following thread is exactly what I did. Hope this is helpful to you and others.


Other useful

Howard, I'm not sure how much of LiteBrite's guidance you have followed, but IMHO it was a bit of a kluge back in 2018 when the logic the JL followed to cold crank an engine was different on some of the early model 2018s than all JLs that came later in that model year and thereafter.

LiteBrite's 2018, like many of the initial ones, would not crank if the ESS battery was dead.

In your 2020, if the ESS battery is dead, the initial crank will fail, but subsequent attempts to crank will occur solely off the main battery.

True, then or now a bad ESS battery connected as per the factory wiring, can rob the main of power.

Still more, LiteBrite's incorporation of a metal nut to connect terminals N1 and N2 of the PDC, a fuse-less method of putting the two batteries in parallel at all times, or, if done in conjunction with removing from the main battery's negative terminal the cable that leads to the negative terminal of the ESS battery and making your JL run on one battery is a technique that IMHO is inferior to the initial methods of fused jumpering of these two terminals as discussed here https://www.jlwranglerforums.com/forum/threads/3-6l-ess-aux-battery-bypass.17293/.

Using a fuse is not only safer but even this technique has in large part been surpassed by its author with another method that its author subsequently discussed, which involves pulling Fuse 42 from the Power Distribution Center (PDC): that same black box under which LiteBrite connects high amp fuses N1 and N2.

Pulling Fuse 42 prevents the energization of a relay that separates the batteries. So effectively, pulling Fuse 42 is the electrical schematic equivalent and safety of putting a fused jumper between N1 and N2 and is the subject of the beginning of this thread.

All this said, given your 2020 there's an even simpler remedy. Disconnect the black terminal on the main battery's negative post that leads back to the ESS battery.

Stop. Your done.

Your first attempt to crank will fail as no ESS battery is connected now and the vehicle behaves like a early 2018, failing to crank. But unlike an early 2018, subsequent attempts to crank will go off the main battery, and if successful, will from that point on only crank, on the first attempt, off the main battery, turning the ESS off light on in the dash.

Only the introduction of an energized ESS battery and reconnection of this cable (or fooling the JL into thinking the ESS battery is still there as is the case with the Fuse 42 pull or fused jumper solution) will turn that ESS off light off. In that case I suggest turning ESS off yourself or with aftermarket tech to do so.

If you don't mind the ESS off light in the EVIC (dash) it's, as I see it a plus. You don't want to run ESS events with one battery normally anyway.

Sir, LiteBrite's technique was itself inferior to the safety of a fuse and has been outdated, no offense to them, by different cold cranking logic in the JL subsequent to the early 2018 models.

Please let me know if you want better advise. I can walk you through what's best once I better know your needs. I cannot help but think that you are following what was inferior guidance that is now, to top that, outdated.

I assure you I do not seek to ridicule you, only to help you.

 

[joliett]

Howard, I'm not sure how much of LiteBrite's guidance you have followed, but IMHO it was a bit of a kluge back in 2018 when the logic the JL followed to cold crank an engine was different on some of the early model 2018s than all JLs that came later in that model year and thereafter.

LiteBrite's 2018, like many of the initial ones, would not crank if the ESS battery was dead.

In your 2020, if the ESS battery is dead, the initial crank will fail, but subsequent attempts to crank will occur solely off the main battery.

True, then or now a bad ESS battery connected as per the factory wiring, can rob the main of power.

Still more, LiteBrite's incorporation of a metal nut to connect terminals N1 and N2 of the PDC, a fuse-less method of putting the two batteries in parallel at all times, or, if done in conjunction with removing from the main battery's negative terminal the cable that leads to the negative terminal of the ESS battery and making your JL run on one battery is a technique that IMHO is inferior to the initial methods of fused jumpering of these two terminals as discussed here https://www.jlwranglerforums.com/forum/threads/3-6l-ess-aux-battery-bypass.17293/.

Using a fuse is not only safer but even this technique has in large part been surpassed by its author with another method that its author subsequently discussed, which involves pulling Fuse 42 from the Power Distribution Center (PDC): that same black box under which LiteBrite connects high amp fuses N1 and N2.

Pulling Fuse 42 prevents the energization of a relay that separates the batteries. So effectively, pulling Fuse 42 is the electrical schematic equivalent and safety of putting a fused jumper between N1 and N2 and is the subject of the beginning of this thread.

All this said, given your 2020 there's an even simpler remedy. Disconnect the black terminal on the main battery's negative post that leads back to the ESS battery.

Stop. Your done.

Your first attempt to crank will fail as no ESS battery is connected now and the vehicle behaves like a early 2018, failing to crank. But unlike an early 2018, subsequent attempts to crank will go off the main battery, and if successful, will from that point on only crank, on the first attempt, off the main battery, turning the ESS off light on in the dash.

Only the introduction of an energized ESS battery and reconnection of this cable (or fooling the JL into thinking the ESS battery is still there as is the case with the Fuse 42 pull or fused jumper solution) will turn that ESS off light off. In that case I suggest turning ESS off yourself or with aftermarket tech to do so.

If you don't mind the ESS off light in the EVIC (dash) it's, as I see it a plus. You don't want to run ESS events with one battery normally anyway.

Sir, LiteBrite's technique was itself inferior to the safety of a fuse and has been outdated, no offense to them, by different cold cranking logic in the JL subsequent to the early 2018 models.

Please let me know if you want better advise. I can walk you through what's best once I better know your needs. I cannot help but think that you are following what was inferior guidance that is now, to top that, outdated.

I assure you I do not seek to ridicule you, only to help you.

So...can you help me, (us) what the summary of your efforts are here. I have deduced so far:
1. Remove ESS battery ground from main battery.
2. Remove fuse 42
3. Turn off the ESS system.
Am I correct here? Am I wrong? I am confused. Please, please let's get this finalized.
I appreciate your efforts.

 

[GrayWolf.Overland]

So...can you help me, (us) what the summary of your efforts are here. I have deduced so far:
1. Remove ESS battery ground from main battery.
2. Remove fuse 42
3. Turn off the ESS system.
Am I correct here? Am I wrong?
I appreciate your efforts.

You only need one approach
simplest being - remove fuse 42, forget that there is an AUX battery and go about your life as usual.

if you are a frequent ESS user.. it will only turn engine off on stop for 6 or 7 times in a trip (trip = cycling on-off). The explanation is a bit long.. short version is - the electronics and sensors detect a mismatch in voltage between the two batteries and tolerates it for 6 times and 7th time it decides to not trigger ESS

 

[Fudster]

You only need one approach
simplest being - remove fuse 42, forget that there is an AUX battery and go about your life as usual.

if you are a frequent ESS user.. it will only turn engine off on stop for 6 or 7 times in a trip (trip = cycling on-off). The explanation is a bit long.. short version is - the electronics and sensors detect a mismatch in voltage between the two batteries and tolerates it for 6 times and 7th time it decides to not trigger ESS

I'm sorry Subash, I do not mean to be disrespectful, but I am of the opinion that your guidance must also include taking the ESS battery out of the electrical schematic of the vehicle by disconnecting the black cable that leads from the negative post of the ESS battery, tucked away under the Power Distribution Center (PDC), from the negative terminal of the main battery, insulating its end, and tucking it away.

Your advise, in absence of the cable disconnect merely puts the two batteries in parallel all the time--which is slightly different from how things work from the factory where, without this Fuse 42 pull, the batteries are in parallel at all times but an instant at cold crank and during ESS events.

I know you realize this from your explanation of how at most 6 ESS events can occur per one engine crank--the JL seeing identical voltages on both batteries because they are never disconnected, presuming (correctly) a short (i.e. Fuse 42 pull) and turning off ESS for the duration of the trip.

But the purposes, at least as I see if, of most people effecting this task is to remove the ESS battery from the vehicle's electrical schematic because the fear of it cannibalizing the main battery exceeds the desire to run ESS events.

I suppose we need to first identify our goals before determining a procedure to be adequate or not. If your wish is to bring both batteries in parallel 100% of the time, then yes, your procedure has perfectly done that.



@joliett


Hi Joel:

I've reviewed your steps above and if your goal is to take the ESS battery out of the vehicle's schematic, do know I concur with your steps but wish to make the following pedantic point.

In our use of the world "ground" I wish things to not get confused. I say this because a battery's negative terminal is referred to as ground--as you know and have done--and there is also a body ground on the passenger's front quarter panel of the JL to which a cable connects it and the main battery's negative terminal (i.e. the battery's ground terminal).

All this said, the cable to remove is NOT the one that connects the main battery's negative terminal to the body ground on the passenger's front quarter panel . That must remain connected.

Rather, remove the other factory cable from the main battery's negative terminal, insulate it and tuck it away, in addition of course to your other steps.

That cable you removed has as its distal end the negative terminal of the ESS battery--and in so doing this you have removed the ESS battery from the vehicle's electrical schematic.

I don't mean to be a pedantic jerk. I just want to make sure that we are on the same page.

 

[Fudster]

There is another point that concerns me. For all their deficiencies I'd rather run an AGM (absorbent glass mat) battery, which is just a Lead Acid type battery, over a Lithium one like the Antigravity product line if below freezing temperatures are common in the operator's locale.

True, the Antigravity's feature automatic self heating provided it is plugged into a charger, but the Lead Acid chemistry doesn't need this feature in the first place.

Yes, all batteries are effected by cold. But trying to tap the Lithium one in such situations can be catastrophic to the battery, deference to Howard's @Wrangler man's Palm Springs warm locale duly noted.

 

[Ratbert]

There is another point that concerns me. For all their deficiencies I'd rather run an AGM (absorbent glass mat) battery, which is just a Lead Acid type battery, over a Lithium one like the Antigravity product line if below freezing temperatures are common in the operator's locale.

True, the Antigravity's feature automatic self heating provided it is plugged into a charger, but the Lead Acid chemistry doesn't need this feature in the first place.

Yes, all batteries are effected by cold. But trying to tap the Lithium one in such situations can be catastrophic to the battery, deference to Howard's @Wrangler man's Palm Springs warm locale duly noted.

They document that their ambient operating temperature only goes down to 23F. Definitely not a viable option for a big chunk of the county.

 

[GrayWolf.Overland]

I'm sorry Subash, I do not mean to be disrespectful, but I am of the opinion that your guidance must also include taking the ESS battery out of the electrical schematic of the vehicle by disconnecting the black cable that leads from the negative post of the ESS battery, tucked away under the Power Distribution Center (PDC), from the negative terminal of the main battery, insulating its end, and tucking it away.

Your advise, in absence of the cable disconnect merely puts the two batteries in parallel all the time--which is slightly different from how things work from the factory where, without this Fuse 42 pull, the batteries are in parallel at all times but an instant at cold crank and during ESS events.

I know you realize this from your explanation of how at most 6 ESS events can occur per one engine crank--the JL seeing identical voltages on both batteries because they are never disconnected, presuming (correctly) a short (i.e. Fuse 42 pull) and turning off ESS for the duration of the trip.

But the purposes, at least as I see if, of most people effecting this task is to remove the ESS battery from the vehicle's electrical schematic because the fear of it cannibalizing the main battery exceeds the desire to run ESS events.

I suppose we need to first identify our goals before determining a procedure to be adequate or not. If your wish is to bring both batteries in parallel 100% of the time, then yes, your procedure has perfectly done that.



@joliett


Hi Joel:

I've reviewed your steps above and if your goal is to take the ESS battery out of the vehicle's schematic, do know I concur with your steps but wish to make the following pedantic point.

In our use of the world "ground" I wish things to not get confused. I say this because a battery's negative terminal is referred to as ground--as you know and have done--and there is also a body ground on the passenger's front quarter panel of the JL to which a cable connects it and the main battery's negative terminal (i.e. the battery's ground terminal).

All this said, the cable to remove is NOT the one that connects the main battery's negative terminal to the body ground on the passenger's front quarter panel . That must remain connected.

Rather, remove the other factory cable from the main battery's negative terminal, insulate it and tuck it away, in addition of course to your other steps.

That cable you removed has as its distal end the negative terminal of the ESS battery--and in so doing this you have removed the ESS battery from the vehicle's electrical schematic.

I don't mean to be a pedantic jerk. I just want to make sure that we are on the same page.

no, not at all.. this is a perfect explanation and I did a lazy version reply thank you for the detailed reasoning esp to understand why the ESS event caps out at 6 ?

 

[Bayrat]

I followed this thread for awhile to gain knowledge regarding the SS on the Wrangler. Now, my wife's 2018 Grand Cherokee is at an age where I know this will leave her stranded somewhere. Has anyone tried the jumper-less method on anything other than the Wrangler?

 

[JeepSki7]

I've read all 26 pages of comments, and there is a LOT of great information... yesterday I replaced my main battery with a 94R. Here's the steps I performed... and the few remaining questions I have.

My jeep is a 2020 JLUR with the 3.6 non-etorque.

Steps I performed:
1. Disconnected and isolated the positive terminal (though I didn't know about the risk of grounding the N3 fuse, I don't think I did allow that to happen though).
2. Put in the 94R battery
3. Reconnected the positive, reconnected the negative then isolated the Aux battery ground as described many times in this thread.
4. Pulled the F42 fuse.

Questions that remain:
1. I still have the "A!" warning light and the "service stop/start system" message on startup.
2. My battery voltage is running 14.4 while driving... if I turn the wheel or something it dips to 13.xx but immediately returns to 14.4... I don't think this is an issue but a few threads have raised concerns about this.
3. How would I know if I faulted/grounded the N3 fuse accidentally?

My plan is to order the smart stop/start device today and install that, but in the meantime manually do it each time I start my Jeep.

Thanks in advance for any input/answers to my questions... I have a feeling @Rhinebeck01 will have the answers (if not several others as well).

 

[JeepWhealen]

Is this something that can (should) be done before the aux battery dies, or wait until I start having crank issues?

 

[jludave]

Is this something that can (should) be done before the aux battery dies, or wait until I start having crank issues?

Don't wait until the aux dies. The bad aux battery will cause the main to have issues.

 

[Impy5]

Will this work for a 2020 with a 2.0? If so do I need to remove both the fuse and the negative to the aux? Read through the thread but was unsure.

 

[Heimkehr]

I'm searching for a low budget non-Taser fix to disable this and do tire size correction anyone have suggestions of a tried and true platform?

If you're asking about disabling the ESS function, I use and recommend this plug-and-play harness. It meets your budget requirement, compared to the expense of a Tazer device. However, the linked harness is a one-trick pony. If you require tire size correction, or really anything else, you'll want to give serious consideration to just purchasing one of the well-regarded Tazer devices. There are two versions, and prices, to choose from.

 

[jludave]

Will this work for a 2020 with a 2.0?

If you have an aux battery, yes.

If so do I need to remove both the fuse and the negative to the aux?

Yes, pull fuse F42 and disconnect the aux cable from the main negative terminal. It should be the skinnier of the 2 cables connected to the terminal.

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